Textiles: knitting – Independent-needle machines – Circular
Reexamination Certificate
2003-03-05
2004-11-02
Worrell, Danny (Department: 3765)
Textiles: knitting
Independent-needle machines
Circular
C066S146000
Reexamination Certificate
active
06810694
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is related to a method for knitting an elastomeric yarn into a circularly knitted fabric.
2. Description of Related Art
It is highly desirable to incorporate elastomeric yarns into knitted fabrics intended for the creation of garments. For example, the elastomeric yarn can provide a degree of elasticity to the knitted fabric, which is useful in many garments such as socks, brassieres, panties, underwear, bathing suits, leotards, and the like.
Generally, incorporating such yarns into a knitted structure as knitted stitches, as opposed to laying-in the yarn, is difficult due to the need to knit these yarns under tension. Further, incorporating such yarns into a knitted structure as knitted stitches is particularly difficult when using circular knitting machines such as those commercially available from Santoni S.p.A. (e.g., Santoni's SM8 knitting machine).
A prime difficulty arises at the start and finish of the knitting process when the elastomeric yarn is introduced and subsequently taken out of the knitting sequence. This difficulty arises from the fact that at the finish of a knitting sequence, the elastomeric yarn has to be severed, but held under tension in readiness for reintroduction at the start of the next knitting sequence.
Prior suction holding mechanisms for nonelastomeric yarns have not proven effective for elastomeric applications. In addition, prior mechanical clamping or holding systems for holding severed elastomeric yarns have proven to be overly expensive and complex.
Difficulties are also encountered in reliably introducing the elastic yarn into the needles for take-up at the start of a knitting sequence. In order to compensate for this difficulty, it is common to slow the speed of the knitting machine. Slowing the knitting machine allows the elastic yarn to be effectively incorporated into the fabric, which has not been possible at normal machine speeds where the elastic yarn tends to pull free from the fabric.
In view of these difficulties, it is common practice to either only introduce bare elastomeric yarn at the beginning of a knitting cycle and knit bare elastomeric yarn throughout the entire cycle, or to have reduced productivity as a result of the slowed machine speeds.
However, there is a continuing desire for apparatus and methods that can provide for the selective elastomeric yarn knitting, while addressing one or more of the aforementioned deficiencies of the prior art.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a method for introducing elastomeric yarns into a knitting cycle in a more reliable manner than previously possible.
It is another object to provide a method for selectively knitting elastic yarns during selected parts of a knitting cycle.
These and other objects of the present invention are provided by a method for circularly knitting an elastomeric yarn into a knitted fabric. The method includes: operating a circular knitting machine at a machine rate, retaining a free end of the elastomeric yarn in a substantially relaxed condition, and taking up the free end into the circular knitting machine while feeding the elastomeric yarn at a first feed rate. The first feed rate maintains the elastomeric yarn in the substantially relaxed condition. The circular knitting machine continues to operate at the machine rate during the taking up of the free end.
A method of knitting an elastomeric yarn with a circular knitting machine is also provided by the present invention. The method includes initiating a first and a second knitting stage. The first knitting stage maintains the elastomeric yarn in a substantially relaxed condition while maintaining a free end of the elastomeric yarn in a desired position. The second knitting stage causes the circular knitting machine to take up the elastomeric yarn in the substantially relaxed condition by positively feeding the elastomeric yarn at a first feed rate. The circular knitting machine maintains the desired machine rate during the take up of the elastomeric yarn.
It is a further object of the present invention to provide a method for knitting elastomeric yarn on a circular knitting machine to produce knitted stitches of the elastomeric yarn. The method includes: retaining a free end of the elastomeric yarn in a substantially relaxed condition in readiness for introduction to needles of the circular knitting machine; introducing the free end for take-up by the needles; feeding the elastomeric yarn at a first feed rate sufficient to maintain the substantially relaxed condition of the free end during take-up by the needles; feeding the elastomeric yarn at a second feed rate to cause tension in the elastomeric yarn to be raised to a desired level during continued knitting; feeding the elastomeric yarn at a third feed rate to cause the elastomeric yarn to be regain the substantially relaxed condition; severing the elastomeric yarn to define a new tail; and retaining the new tail in the relaxed condition.
The above-described and other features and advantages of the present invention will be appreciated and understood by those skilled in the art from the following detailed description, drawings, and appended claims
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Ohlandt Greeley Ruggiero & Perle
Sara Lee Corporation
Worrell Danny
LandOfFree
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