Textiles: knitting – Feeding – Strand tensions
Patent
1986-08-01
1987-06-16
Feldbaum, Ronald
Textiles: knitting
Feeding
Strand tensions
D04B 1544
Patent
active
046728244
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to flat-bed knitting machines and, more particularly, to yarn restraining devices for controlling the feeding of yarns to such knitting machines.
A flat-bed knitting machine conventionally comprises a flat elongated bed on which is mounted an array of parallel latchable knitting needles. The needles are disposed transversely to the length of the bed at equally spaced positions therealong and are reciprocable in the direction of their length so as to be sequentially projectable from one side of the bed. They are reciprocated in response to movement of a carriage or cam box slidable along the bed transversely to the needles and having a cam arrangement for engaging operating butts of the needles. The cam box is pushed backwards and forwards along the bed and, as the cam box is moved, the yarn is fed to the projecting front ends of the needles, via suitable guide means disposed on the cam box, so that each needle knits a stitch as it is reciprocated by the cam arrangement.
At the end of each stroke of the cam box along the bed, the cam arrangement must clear the operating butts of a selected array of working needles before it can commence a reverse stroke. Consequently, the cam box carries the yarn some distance past the end needle of the selected array before its movement can be reversed and this causes a loop of slack yarn to form at the start of the next row of stitches which can result in dropped stitches. The customary method of taking up this slack is to thread the yarn being supplied to the cam box through a guide assembly incorporating a spring device normally, either a wire or coil spring. The spring is kept under tension whilst a row of stitches is being knitted so that, when the cam clears an end working needle and the direction of movement of the cam box is reversed, the spring restores and takes up any slack yarn. A consequence of such conventional arrangements is that the yarn is always under tension during the knitting of a row of stitches and this tension must be controlled to avoid dmage to or jamming of the yarn, as it passes through the spring guide assembly, and to produce constant stitch sizes. This control is difficult to achieve with conventional arrangements.
An object of the present invention is to provide a yarn restraining device for a flat-bed knitting machine of the type described above, which is arranged to control the supply of yarn so that no loops are formed at the edges of the knitted fabric produced on the machine and which does not itself apply tension to the yarn whilst rows of stitches are being knitted, although the yarn may be otherwise tensioned.
The invention consists in a yarn restraining device for positioning on such a flat-bed knitting machine or at adjacent one end of the stroke of the cam box, which device comprises a spring arm for engaging with a cooperating surface on the cam box during movement thereof over a predetermined end portion of its stroke and for trapping the yarn between itself and said surface, said arm being adapted to retain the yarn so trapped as the cam box commences a reverse stroke and until the yarn is reengaged by the cam box with the adjacent end working needle, thereby to take up slack in the yarn produced at the end of a cam box stroke and avoid the formation of loops between rows of stitches.
In use, the two such yarn restraining devices are mounted on the bed of the knitting machine at opposite ends of a selected array of working needles. The cooperating surface on the cam box may be a surface of the cam box, itself, or alternatively, a surface on a component affixed to the cam box.
Conveniently, each yarn restraining device comprises an arm formed from spring strip material, such as spring metal strip, arranged to project longitudinally of the bed of the knitting machine and engage with a flat upper surface of the cam box. The cam box may have a central yarn guide adjacent the path of movement of the spring arm in contact with the cooperating surface of the cam box so that the yarn is automatically guid
REFERENCES:
patent: 214309 (1879-04-01), Nelson
patent: 2115610 (1938-04-01), Ball
patent: 3797279 (1974-03-01), Kline et al.
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