Textiles: knitting – Feeding – Positive
Patent
1984-12-04
1986-12-16
Reynolds, W. Carter
Textiles: knitting
Feeding
Positive
66138, 66163, D04B 3512, D04B 3516
Patent
active
046287108
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a yarn-feeding apparatus for the selective positive feeding of several yarns to a knitting machine and to a method for controlling the operation of a yarn-feeding apparatus.
BACKGROUND OF THE INVENTION
A yarn-feeding apparatus of the type to which the invention relates is disclosed in the applicant's own non-prepublished European patent application No. 83 105 136.2 and in the applicant's own international patent application having the application number PCT/EP8300 131. These prior applications describe a yarn-feeding apparatus having a plurality of yarn-feeding wheels which are freely rotatable. These wheels are driven by respective belts engaging a portion of the circumference thereof. These belts are driven in synchronism with the knitting machine in order to supply a plurality of yarns from spools to the knitting machine. Yarn-feeding elements having eyelets for guiding the respective yarns are rotatably supported about an axis perpendicular to the axis of the wheels. The yarn-feeding elements comprise input-guiding elements and output-guiding elements fixedly connected to each other and pivotally supported with respect to said axis. If the knitting machine puts tension on a yarn which is to be fed to the knitting machine, the corresponding yarn-feeding element pivots against the force of a spring, whereby the input-guiding element of this yarn-feeding element urges the corresponding yarn between the belt and the freely rotatable wheel. Hence, the yarn is positively fed to the knitting machine if the knitting machine puts tension to this yarn. During usual operation of the knitting machine, only one yarn is positively fed by the apparatus. In case a change of colour is required, the knitting machine terminates the knitting operation carried out with one yarn, reduces the tension occurring in this yarn and thereby enables the spring to pivot the yarn-feeding element such that the yarn comes in the non-feeding area of the feeding wheel. Thereinafter, the tension in the yarn to be knitted next rises, so that the corresponding yarn-feeding element pivots in its feeding position, in which the yarn comes in the region of engagement of the belt and the feeding wheel. Each yarn-feeding element comprises a sensor generating a sensor signal representing the feeding-position or non-feeding position of the respective yarn-guiding element and thereby representing the respective feeding condition or non-feeding condition of each yarn.
During normal operation, i.e. if no yarn breakage or yarn over-feed or yarn change fault occurs, only one yarn is fed to the knitting machine, so that only one sensor generates a signal. During the changing of the yarn fed to the knitting machine, a simultaneous generation of two sensor signals in case of a knitting machine having an overlapping feeding of the old yarn and the new yarn or the generation of no signal in case of a knitting machine having a non-overlapping feeding of the old yarn and the new yarn takes place during a relatively short period of time. In case of a yarn breakage or a yarn over-feed, no signal is generated by the sensors. In case of a "two yarn"-condition caused by a yarn change, i.e. a fault of simultaneous feeding of at least two yarns to the knitting machine, two sensor signals are generated. Hence it is possible to detect a yarn breakage and a yarn over-feed or a two yarn condition by checking whether a sensor signal combination representing the feeding of no yarn or the feeding of at least two yarns occurs during a period of time exceeding the period of time of the yarn changing operation. For this purpose the apparatus comprises an error detection unit connected to the sensor means for turning off the knitting machine in response to predetermined sensor signal combinations representing a yarn breakage and/or a yarn over-feed and/or a yarn change fault which occur during a period of time exceeding a predetermined time limit. In other words, only sensor signal combinations occurring during a perio
REFERENCES:
patent: 4031718 (1977-06-01), Luth
patent: 4386508 (1983-06-01), Jacobsson
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Reynolds W. Carter
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