Textiles: knitting – Stopping – Strand controlled
Patent
1997-10-30
1999-04-20
Falik, Andy
Textiles: knitting
Stopping
Strand controlled
66132R, 66146, 242 4701, 250548, 2505594, 139452, D04B 1548
Patent
active
058947442
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The invention relates to an apparatus for the control of the rotational speed of a driving-unit for a yarn windings storage drum, as customarily used with devices for storing and delivering yarns in textile machines.
Such an apparatus is particularly useful for machines, which during the progress of the manufacturing process show continuously or even only intermittently an irregular consumption of yarn, as occurs for instance with knitting or hosiery machines, which inter alia knit special patterns of knitwear or rely on jacquard systems, or operate according to stripe patterns, or with shuttle systems or systems which knit plush. The apparatus is also applicable to straight knitting machines or to looms with so-called thread shots.
It is an object of the invention to eliminate the tension differences which appear in the unwinding of yarn from a yarn bobbin as a consequence of the variation of the bobbin diameter and yarn speed. A further object of the invention is to at least to eliminate or simplify the conventional means for guiding, braking and controlling the yarn to minimize the unwanted yarn tension increasing effect.
By inserting such an apparatus in between the yarn bobbin and the knitting point, it is aimed at obtaining principally a uniform knitwear as to length and knitting quality (for instance the pattern of the stitches) and at obtaining a higher efficiency of the machine as a consequence of less disturbances, for instance caused by yarn breakings.
It is already known in circular knitting machines to rely on the method which provides that all yarns to be processed are supplied through yarn delivery devices, which have additionally the task to stop the machine when a yarn break occurs, so as to avoid or at least to strongly limit the damaging of needles and cylinders which otherwise would inevitably occur. The yarn winding serves here as an additional reserve. However the problems in such circular knitting machines are much simpler, at least with the knitting of so-called straight or approximately straight knitwear, if compared with the requirements existing in a comparable apparatus for supplying the yarn in connection with an irregular, i.e. intermittent, yarn consumption, as occurs in the textile machines of the kind above mentioned.
In such known devices for circular knitting machines, as a consequence of the synchronism between the movement of the machine cylinder and the consumption of the yarn of each single knitting point, it is possible to supply the yarn, through relatively simple mechanical means, in correct quantities. Practically, such yarn supply devices are directly driven, mostly in a synchronous way through a continuously adjustable gear device, which is controlled through a toothed belt or the like by the machine cylinder.
For obvious reasons such a yarn supply device is not applicable to textile machines with an intermittent yarn consumption. The sudden variations of the speeds of the yarn which occur with such machines while the cylinder is per se constantly operated cannot be performed by any yarn bobbin of a conventional yarn supplying device. Accordingly, in this complex field so-called storage drums are used in order to solve the problems which are posed.
Of these so-called yarn storage means, there are at least two main forms: one form provides for a yarn storage drum which is intermittently brought to a standstill, which has a rotating winding means which winds up the yarn on the storage drum; the other form provides only for a rotating storage drum, on which the yarn is wound.
The common feature of such embodiments is the principle of the winding of the yarn on a storage drum, so as to render ready a sufficiently large reserve of yarn, while sensitive means ascertain in due time when the yarn reserve has to be replenished as a consequence of the unwinding requested by the textile machine. A further common feature is the fact that collector-free three-phase electrical motors are provided for their driving, which do not suffer from wear. T
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