Textiles: knitting – Independent-needle machines – Circular
Reexamination Certificate
2003-02-14
2004-05-18
Worrell, Danny (Department: 3765)
Textiles: knitting
Independent-needle machines
Circular
Reexamination Certificate
active
06735987
ABSTRACT:
TECHNICAL FIELD
The invention relates to a circular knitting machine for the production of plush fabrics which have a ground knit produced from ground threads and plush threads tied into said ground knit and comprising a needle cylinder with knitting needles intended for stitch formation, a sinker ring with sinkers intended for the formation of plush-thread loops, and a plurality of knitting systems, each with a means for controlling the knitting needles into a knock-over position after the pick-up of ground and/or plush thread.
BACKGROUND OF THE INVENTION
Numerous embodiments of circular knitting machines for the production of plush fabrics are known. They have, as a rule, a needle cylinder provided with knitting needles and a sinker ring provided with sinkers. The plush fabrics obtained by them consist of what may be referred to as a ground knit, which is usually a fabric produced with a special ground thread and by the right/left or plain type of knitting, and of plush threads tied into the ground knit.
In plush fabrics of this type, pattern effects may be achieved, in particular, in that differently coloured plush threads are used or the plush threads are processed into plush loops of different length. The patternings mentioned first are designated as coloured patternings and the others as structural patternings.
To achieve coloured patterns, for example, circular knitting machines of the generic type designated in the introduction are known (DE 31 45 307 A1), in which first a ground thread and then, according to the pattern, one of a plurality of differently coloured plush threads can be inserted into all the knitting needles accommodated in the needle cylinder.
A particularly full and dense plush fabric is thereby obtained. A particular feature which, as a rule, is undesirable in coloured patternings of this type is due to the fact that floats occur wherever the plush threads are not inserted into the knitting needles. If floats of this kind extend over more than a few stitch wales, they disturb the visual appearance of the fabric. They are therefore eliminated by means of a shearing operation carried out after the knitting operation, the result of this, moreover, being that the plush loops formed are automatically cut open. The same applies correspondingly when plush fabrics having coloured patterns are produced by the plush threads being tied in partial rows into the ground knit, that is to say when in each stitch row, according to the pattern, only plush threads of a single colour are processed into stitches and laid in a floating manner therebetween, so that less full and dense plush surfaces are obtained. Consequently, all the plush fabrics described have, as a rule, what may be referred to as a velours surface, that is to say, when this knitting technique is employed, it is not possible to produce plush fabrics which have terry cloth surfaces provided with uncut plush loops.
One advantage of the type of knitting described is that it can also be used for the production of structural or high/low patterns. For this purpose, floats are formed in selected regions of a knit by means of all the plush threads which occur, so that, after the shearing operation, only the ground knit remains in these regions and is visually apparent (DE 39 27 815 A1, DE 197 07 053 A1). The formation of floats is in this case the equivalent to formation of loop-free zones or to a selection “no plush loops”. The plush fabrics produced in this way, moreover, may be provided to a restricted extent with a coloured or knitted pattern by means of the additional insertion of float threads or further ground threads.
Coloured and structural patternings may, in principle, also be produced by means of other known circular knitting machines of the generic type designated in the introduction. For example, it is known (U.S. Pat. No. 2,710,527) to feed ground threads only to those knitting needles into which a plush thread is also inserted according to the pattern such that coloured patternings can be produced, in principle, only with the aid of partial rows. In plush fabrics produced in this way, therefore, the ground threads also float in the regions free of plush threads, in addition to the plush threads, which, on the one hand, may lead to a visually ugly appearance and to undesirable material properties and, on the other hand, entails the risk that, during the shearing operation, the ground-thread floats are also removed together with the plush-thread floats. To avoid this disadvantage, circular knitting machines are known (DE 30 24 705 A1) which serve the purpose oft when relatively long ground-thread floats occur, of controlling some selected needles into a knitting or tucking position, in order thereby to process the ground thread in the region of the floats partially into a stitch or to anchor it as a tuck stitch in the ground knit. Since the floating ground thread is tied into the ground knit at only a few points, there is at the same time the advantage that the number of tie-in points is kept low and no ugly bare gaps occur during the production of coloured patternings by means of partial rows. In addition, although it is also possible to provide comparatively wide regions in the plush fabric which have no plush loops at all, nevertheless, in this type of knitting, the main preoccupation is always to avoid long ground-fabric floats in regions having plush loops.
The circular knitting machines described hitherto are therefore all used, in particular, for the production of plush fabrics with coloured patternings. Existing pattern devices for the independent individual selection of knitting needles serve in this case merely for the purpose of separating those knitting needles which are to pick up a plush thread from the remaining knitting needles. By contrast, for all other patternings, in particular for high/low patterns in plush-thread regions or for knitted patterns in ground-thread regions, only cam parts are available which act on pattern butts, assigned to them, on knitting needles or on jacks assigned to these, so that the patterning possibilities are in this respect highly limited. This would in no way be changed even by the use of interchangeable cam parts which allow patternings, such as, for example, 1:1 tuck/float or 1:1 knit/float, and which are exchanged, as required.
A hitherto unavoidable problem of the circular knitting machines described is that the selection “no plush loops” is possible only by the production of floats and the subsequent elimination of the floats by shearing. Consequently, knitted fabrics produced on these circular knitting machines, in so far as they are provided with structural patterns, always contain regions with stitches formed from ground and plush threads and regions with stitches formed solely from ground threads. In this case, in the regions free of plush threads, it is only the ground threads which determine the appearance of the plush fabric.
To avoid these properties which are not always desirable, circular knitting machines are known (U.S. Pat. No. 1,790,832, GB 1,104,859) which have pattern devices for selecting the sinkers and partially also additional pattern devices for selecting the knitting needles picking up the plush threads. The sinkers can in this case be controlled, according to the pattern, at least into a first position, in which plush loops are formed by means of a lower-lying sinker edge, or into a second position, in which plush loops are formed by means of a higher-lying sinker edge. The lower-lying sinker edges usually correspond in this case to those with which the ground-thread stitches are produced or looped. The plush loops produced by means of the lower sinker edges may in these cases also be designated as “neutral loops” or no loops”. By these are meant, within the scope of the present invention, plush-thread loops which have essentially the same length as the ground-thread loops or legs and therefore, in the finished knit, lead to double stitches consisting of ground and plush threads, but do not appear as plush loops projecti
Bizer Erich
Plath Ernst-Dieter
SIPRA Patententwicklungs-und Beteiligungsgesellschaft mbH
Striker Michael J.
Worrell Danny
LandOfFree
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