Textiles: knitting – United needle machines – Straight
Reexamination Certificate
1999-04-14
2001-08-21
Worrell, Danny (Department: 3741)
Textiles: knitting
United needle machines
Straight
C066S12500A
Reexamination Certificate
active
06276174
ABSTRACT:
The invention is concerned with a method and a warp knitting machine for the production of a knitted fabric having a freely selectable weft thread pattern repeat.
BACKGROUND OF THE INVENTION
According to the state of the art, methods and warp knitting machines are known in which the weft thread pattern repeats can be influenced, however in relatively narrow margins. Principally, three ways for raising the pattern possibilities of the warp thread pattern repeats are known. In one, an influence of the warp thread pattern repeat is the result of a flexible arrangement of the weft thread carriage with off-set rakes, and in another, the influence is the result of a continuous movement of the transport chain of the warp knitting machine whereby the relationship between the fabric repeat and the weft thread repeat can be enlarged. Finally, it is known to influence the number of the knitted-in weft threads during a stitch forming phase by changing the movement sequence of the knitting elements.
DE 196 04 422 A1 describes a driving arrangement for working elements, especially, multiple thread guides on a weft carriage of a warp knitting machine. The weft carriage as well a the multiple thread guides thereon are each driven by a position regulated drive motor. This serves to realize the goal to reduce the mass to be moved and to shape their movements in a most variable way. Because of these position regulated drive motors, the rack movement of the multiple thread guides is correlated with the movement of the weft carriage whereby the type of laying-in of the weft thread sheets can be changed. The transport chains that lay-in the weft threads into the fontour of the warp knitting machine are driven continuously.
The disadvantage of this known arrangement consists in that by using multiple thread guides as working elements, the weft threads can only be deposited in groups and thereby can only be guided in groups into the knitting area of the warp knitting machine. When the number of the weft threads that are assembled in a group by way of the multiple thread guides and deposited by the same has to be changed, and it is necessary to change the number of the weft threads assembled in a group it is necessary to modify the machine which considerably decreases the flexibility of such a machine, with regard to the weft thread pattern repeat.
DE 39 32 184 C2 also describes a weft carriage having an off-set rake mounted thereon. The drive arrangement for the weft carriage is coupled with a computer by way of which a freely selectable movement principle for the weft carriage as well as for the off-set rake can be realized in dependency from the rotational angle position of the main drive shaft of the machine. The realized movement principle serves to match the differing thread materials. The longitudinal conveyors operate continuously and thereby convey the weft threads to the knitting area of the warp knitting machine after having been deposited into hooks.
DD 256 532 A1 further describes a control system for a weft laying carriage. Thread guiding blocks (multiple thread guides) are movably arranged on a changeable weft thread laying carriage. Thereby, any respective thread sheet is layed-in according to the control of the weft carriage and then, however, is continuously guided to the knitting area of the machine by way of the longitudinal conveyors.
Furthermore, from DE 30 40 393 C2, a weft thread magazine with return weft for a warp knitting machine is known. Thread guides have been arranged on a weft carriage and the weft carriage is moveable independently from the continuously unchanging movement of the longitudinal conveyors.
Because of the fact that the thread guide group is adjustable from an effective position wherein weft threads are deposited in groups into holders to an ineffective position where no transfer of weft threads into holders occurs, a group of weft threads can selectably be laid or not, whereby the longitudinal conveyors continue to move unimpaired. On one hand the weft threads can be laid with differing diagonal angles and on the other hand, the weft threads can be laid alternatively parallel or diagonal. Always, however, the weft threads are being deposited in groups and can only be guided in groups to the knitting area of the warp knitting machine. An enlargement of the pattern repeat is possible, however, the weft thread pattern multiplicity is greatly diminished.
DE 31 28 024 C2 describes a warp knitting machine having a warp thread magazine including longitudinal conveyors having a drive arrangement which induces a lower speed in the longitudinal conveyors that is lower than a normal speed. It also includes a pattern device by way of which the weft thread forwarders are effective only during part of the needle lifts. From DE PS 16 85 392 it is already known to reduce the conveying speed of the longitudinal conveyors which makes it possible to deliver a weft thread to only every second or third stitch row, for example, that is, it is thereby possible to create weft free stitch rows even though all holders of the longitudinal conveyors have weft threads therein. The longitudinal conveyors are driven by way of a drive shaft in a slow but always existing drive speed, whereby the speed is a result of an adjusting device having variously formed gearing therein. A disadvantage of the described warp knitting machine consists in that the rotational movement of the drive shaft for the longitudinal conveyors is derived from the main shaft of the warp knitting machine, that means, that the longitudinal conveyors are driven on a permanent basis. Thereby, the flexibility with regard to the obtainable weft thread pattern repeat is considerably diminished.
Further, DE-OS 21 14 700 describes a knitted fabric with through or full weft threads in which the weft threads are supposed to create some kind of a cross knob effect. Therefore, two or more weft threads at arbitrary intervals are bound-in by way of loops instead of stitches. The variation of the number of the weft threads is thereby obtained by changing the movement flow of the knitting elements. A disadvantage in the method of producing the fabric just described is that in obtaining the loops which are required for the binding-in of several weft threads for each stitch, is only possible by stopping the knitting needle in its upper position. This requires that the slide must be controlled in such a manner so that it can be disengaged which results in that the movement and the drive of the knitting elements is shaped in a complicated way and further results in a relative low number of machine rotations.
All of the three described types of influencing the weft thread pattern repeats have in common is that the weft thread pattern repeat, especially with regard to its flexibility in its construction is only variable in relative narrow limits.
OBJECTS OF THE INVENTION
A basic object of the invention consists in the creation of a method for the production of a knitted fabric and a warp knitting machine to realize the method by way of which the weft thread pattern repeat is freely selectable with extreme high flexibility and an arbitrary long length.
This object is achieved by way of the method having the characteristics of claim
1
and by way of the warp knitting machine having the characteristics of claim
10
. Further developments are defined in dependent claims.
In the method for the production of a knitted fabric according to the invention having an indefinite long and freely selectable weft thread repeat, the weft threads are introduced into the area of the knitting elements by way of a weft insertion system and by way of longitudinal conveyors. According to the invention, the longitudinal conveyors are driven independently from the warp knitting machine on which the knitted fabris is being produced, at least partially intermittently and/or at least at times with varying speeds. Having the possibility of driving the longitudinal conveyors in a controlled manner intermittently and in an operating mode with a varying speed, the we
Maier Stefan
Wunner Roland
Banner & Witcoff , Ltd.
Liba Maschinenfabrik GmbH
Worrell Danny
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