Textiles: knitting – United needle machines – Straight
Reexamination Certificate
2000-01-19
2001-04-03
Worrell, Danny (Department: 3741)
Textiles: knitting
United needle machines
Straight
C066S204000, C066S08500A
Reexamination Certificate
active
06209362
ABSTRACT:
TECHNICAL FIELD
The invention relates to a warp knitting machine, especially a crochet galloon machine, having knitting needles which are guided on a knock-over bar and which include warp guide bars having warp guides and weft guide bars having and weft guides.
PRIOR ART
A warp knitting machine of the type mentioned in the introduction is known, for example, from DE-A-27 58 421. In this warp knitting machine, the weft guide bars and the weft guides arranged thereon must be moved not only to and fro along the weft guide bars, but also up and down, in order to underlay a corresponding weft yarn on a knitting needle. In this case, the weft guide bars are exposed to a very high dynamic load, thus resulting in sagging, wear and high noise emission. In order to counteract this, the bars must have a very large cross-section and therefore require a large amount of space. This space requirement, on the one hand, and the only limited free space available on the warp knitting machine, considerably restrict the maximum number of weft guide bars, for example to eight. An improvement to a maximum of sixteen can be achieved by improving the design according to WO 94/23 106. In this case, two weft guide bars are designed so as to be one above the other and so as to engage one into the other. In this design too, there are still the disadvantages that the weft guide bars have to be moved not only to and fro but also up and down, so that high inertia forces, strong vibrations, high noise emission and wear occur. The maximum speed of such warp knitting machines is therefore restricted, for example to 1200 revolutions/minute. In addition, in view of the fact that an ever smaller needle gauge of four to ten needles per cm is demanded nowadays, the knitting needles have very thin cross-sections, with the result that the needles are highly susceptible to flexions and oscillations. At the present time, it is customary to restrict the maximum free knitting needle length to approximately 50 times the needle thickness in the gauge direction. The warp yarns are inserted into the knitting needle heads when the needles are in the extended position. The distance between the knock-over bar and this extended position is available for the number of racking rows for weft guidance and, at the present time, amounts to a maximum of seven rows. Yarn guides having tips or having small end tubes serve for laying the weft yarns under and between the knitting needles. Furthermore, the tip of the yarn guide may also be provided with a small end tube which, however, takes up a relatively large amount of space. The racking gauge is therefore nowadays, on average, approximately 3 mm. This restricts the number of racking levels to seven, on the assumption of a knitting needle stroke of 25 to 30 mm. Also because up to seven yarn guide tips, which have to engage into a knitting needle gap between the knitting needles, cannot be oriented exactly in one line, there is contact with the knitting needles, and these begin to vibrate or may be damaged, thus impeding insertion of the warp yarns in the knitting needle heads and greatly restricting the rotational speed of warp knitting machines.
Since, on the one hand, the yarn guides for laying the weft yarns under the knitting needles have to penetrate into the knitting needle gaps and since, on the other hand, the guidance of weft yarns over long distances is driven via a crank mechanism, a certain number of knitting needles must be omitted at the reversal point of the yarn guide. This affords the disadvantage that the useful knitting length is reduced or that weft guidance must be driven via cam mechanisms, thus, in turn, restricting the maximum rotation speed of warp knitting machines.
According to the prior art, the knitting point is designed on the crochet galloon principle, as a result of which it is not possible for the yarns to be beaten up on the selvedge. This affords the disadvantage that it has hitherto been possible to produce only knitted fabrics having a relatively low weft density. The area of use of warp knitting machines is thereby restricted.
SUMMARY OF THE INVENTION
The object of the invention is to improve a warp knitting machine of the type mentioned in the introduction.
The set object is achieved by means of the provision of weft guides which do not cross through the knitting needles and the assignment of feeders to the weft guides, which feeders are guided and can be driven up and down between the weft guides and the knitting needles transversely to the racking direction of the weft guide bars. This enables the feeders to lay racked weft yarns under the associated knitting needles
Since the weft guides of the weft guide bars do not intersect the knitting needles, they also do not have to be moved up and down, a to-and-fro movement instead being sufficient. The weft yarns are supplied to the knitting needles by the feeders. This results in an appreciable simplification of the weft guide and of the weft guide bars, so that a very large, hitherto impractical number of weft guide bars and weft guides is possible. The number of racking rows is also no longer necessarily restricted, so that the maximum possible number is equal to the number of installed weft guide bars. Furthermore, the knitting needle stroke can be reduced to a minimum size, since there need only be space for a single feeder in a knitting needle gap between the knitting needles. The knitting needle stroke is therefore essentially dependent on the width of the feeder. Since the weft guides no longer enter the knitting needle gaps between the knitting needles, operation is possible with weft guidance of virtually any length, without any loss of knitting needles. This may be further assisted by using electronically controlled drives for driving the weft guide bars, the said drives allowing smooth motion so as to treat the weft yarns carefully.
Advantageous embodiments of the invention are further described herein.
It is possible in principle for the weft guide bars to execute not only a to-and-fro movement, but also a movement transverse to this, provided, however, that the weft guides do not intersect the knitting needles. It is more advantageous, however, if the weft guide bars and therefore also the weft guides execute only a to-and-fro movement in their longitudinal direction, thereby appreciably simplifying the drive and mounting, so that a larger number of weft guide bars and consequently weft guides may be used. It is also advantageous if the knitting needles execute only a to-and-fro movement along their knitting axis.
It is possible in principle for not every knitting needle to be assigned a feeder, but the embodiment wherein each knitting needle is assigned a feeder is more advantageous.
It is conceivable that the feeders do not cross through the weft guides of the weft guide bars and the knitting needles, but run at a distance from these. However, an embodiment wherein the feeders cross through the weft guides of the weft guide bars and the knitting needles in a finger-like manner is especially advantageous, the result of this being that not only is a more compact design achieved, but the operating capacity of the warp knitting machine is also increased.
The feeders may, if appropriate, be driven individually or in groups, but an embodiment wherein the feeders are arranged on a common, drivable on a common feeder bar is more advantageous.
The feeders may be movable along a straight path and/or along arcuate paths. Especially advantageous is a design wherein the return travel of the feeder from the knitting point is arranged at a distance from the weft guides, which makes it possible for the return travel of the feeders to lie outside the weft guides, so that racking of the weft guide bars can take place as early as during the return travel of the feeders.
As regards the arrangement of the weft guide bars together with the weft guides, various possibilities arise, such as, for example, wherein the weft guide bars together with the weft guides are arranged in such a way that the weft yarns ar
Hovey Williams Timmons & Collins
Textilma AG
Worrell Danny
LandOfFree
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