Textiles: knitting – Independent-needle machines – Circular
Reexamination Certificate
2000-09-22
2001-10-16
Worrell, Danny (Department: 3741)
Textiles: knitting
Independent-needle machines
Circular
Reexamination Certificate
active
06301938
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to circular knitting machines and more particularly to an automatic fabric density adjusting device and yarn feeding control mechanism therefor.
BACKGROUND OF THE INVENTION
It is highly desirable in knit fabrics to have the stitch loops as uniform as possible. Various changeable conditions affect the size and volume of the stitch loops being formed on a circular knitting machine. Examples of such changeable conditions include the tension in the yarn being fed to the needles, the stroke of the needles and the speed of rotation of the cylinder.
One way to control the tension in the yarn and thus the stitch volume is to adjust the yarn-feeding speed. One such known device is disclosed in JP-B-3-72738 (1991). While somewhat effective, this device is complicated, complex in that it embodies many components and costly to manufacture. Therefore, it has not been found to be a solution to the problem.
Another approach to controlling stitch size and volume is to adjust the size of the stitch loops by raising and lowering the stitch cam support to vary the stroke of the needles during stitch formation. Examples of such stitch loop adjusting mechanisms are disclosed in U.S. Pat. Nos. 5,174,133 and 5,511,392. In both of these prior mechanisms, feeding characteristics of the yarn or yarns, such as yarn tension or quantity of yarn fed, are measured and the stitch cam height adjusted responsive to the differential in that measurement and a pre-set value. While more effective than previous attempts, these mechanisms relied primarily upon only one or two of the variables on changeable conditions affecting stitch size or volume and were therefore limited in their responsiveness and in the improvements in fabric quality they could achieve.
SUMMARY OF THE INVENTION
With the foregoing in mind, it is an object of the present invention to provide a circular knitting machine for forming knit stitch loops of more uniform size and volume and a fabric density adjusting system including an improved yam feeding mechanism for automatically adjusting the yarn feeding volume to the needles of a circular knitting machine, the stitch volume and the fabric take-up rate.
This object of the present invention is accomplished by providing an automatic yarn-feeding mechanism equipped with a detecting device for monitoring or detecting the rotary movement of the knitting machine and a driving means for driving the yam feeding mechanism in accordance with such rotary movement. Also, an automatic fabric density adjusting system incorporating this yarn feeding mechanism is provided. More particularly, the fabric density adjusting system includes a tension detector for sensing the tension in the yam being fed to the needles of the knitting machine, means for varying the stitch volume in accordance with the sensed variation in yam tension, means for detecting variations in fabric tension and means for adjusting the fabric take-up rate accordingly.
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Kawase Yoji
Kitagawa Kyoya
Nagai Hiromasa
Nakamura Yasuo
Takeuchi Shunji
Alston & Bird LLP
Precision Fukuhara Works, Ltd.
Worrell Danny
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