WO2008017340A1

WO2008017340A1 - Apparatus for producing a knitted fabric

Info

Publication number: WO2008017340A1
Application number: PCT/EP2007/005070
Authority: WO
Inventors: Gerd Stahlecker
Original assignee: Spindelfabrik Suessen Gmbh
Priority date: 2006-08-07
Filing date: 2007-06-08
Publication date: 2008-02-14
Also published as: DE102006037714A1

Abstract

An apparatus for producing a knitted fabric is described, having a knitting device (1) which comprises knitting needles (16) and at least two knitting points (15). A drawing frame (4, 5, 30) for producing a drawn fibre composite (3) is arranged in front of each knitting point. The geometry of the profile of the drawn fibre composite is identical in a region (21) in front of each knitting point. The region extends from the knitting point at least as far as the last active transport element (17) for the drawn fibre composite. The last active transport element for the drawn fibre composite can be a delivery roll pair (11) of the drawing frame, a delivery unit (18) or an air nozzle (26). In addition, the speed of the drawn fibre composite at the last active transport element can be variable.

Description

Device for producing a knitted fabric

The invention relates to a device for producing a knitted fabric with a knitting needles and at least two knitting points containing knitting device, each knitting point is preceded by a drafting device for producing a warped fiber structure.

A device of this kind is known from WO 2004/079068 A2 prior art. In this case, a knitted fabric is not produced as usual from a yarn which is supplied to the knitting device, but knitted directly from a distorted by a drafting fiber structure. The advantage is that the knitting of a substantially untwisted fiber structure with almost parallel fibers results in an extremely soft knit with a very soft feel and a correspondingly high wearing comfort. The knitwear can also be made very cheap, since the intermediate stages of the classic yarn production process, namely the yarn formation, the winding and possibly the rewinding are bypassed.

The consisting of staple fibers fiber strand is either untwisted fed immediately working in the knitting knitting needles or, if the drafting is arranged in a certain spatial distance from the knitting, provided by a twisting device with a certain strength that allows transporting to the knitting. Since the fiber structure for transport to the knitting need not have a particularly high strength, a slight rotation of the fiber structure is sufficient. This can be very well introduced by air nozzles in the fiber structure. Once the fiber structure has been entangled in the knitting device to form the knitted fabric, the strength of the knit fabric is ensured by the entanglement of the fiber structure in the individual stitches. A rotation of the fiber structure is no longer necessary, quite the contrary, even the yarn twist contained in conventional knitwear leads to a rather "hard grip ^{1 of} the finished fabric. Particularly advantageous is the use of a false twist device, since the for the Transport strength of the fiber structure introduced rotation during knitting in the StrickstelJe dissolves again. It can also be provided to supply the fiber structure in the drafting system an auxiliary thread, for example an elastane thread, which can assist the transport of the fiber structure from the drafting system to the knitting point and can also further specifically improve the properties of the knit fabric produced. The described method is also referred to as "direct knitting" or "spinning knitting".

From WO 2004/079068 A2 it is known to combine several drafting systems to form a drafting group and to drive them by a common drive. The output roller pairs of the drafting units rotate thereby all at the same speed, so that the warped fiber composites are supplied at the same speed. Tests have shown that the knitted fabric produced with such a device often undesirably has cracks caused by differently shaped stitches and makes the finished knit look uneven. As a result, the quality of the knitwear can be reduced.

The invention is based on the object to improve the apparatus for producing a knitted fabric in order to produce a knit fabric high uniformity can.

The object is achieved in that the geometry of the course of the warped fiber structure in a region in front of each knitting point is the same, the area extending from the knitting point to at least the last active transport element for the warped fiber structure.

The Applicant surmises that in the device known from WO 2004/079068 A2, the different course of adjacent fiber composites from the pairs of output rollers of the drafting systems to the knitting points causes different stresses of the fiber assemblies in the finished fabric. Although all the fiber bundles are supplied at the same speed by the common drive of all drafting units of a drafting group, the geometry of the feed paths differs with regard to the feed line length and the feed line orientation. Each fiber structure is diverted differently, which leads to different friction conditions. As a result, the fiber bandages processed in the knitting points have different tensions, which can lead to the aforementioned undesirable brittleness in the finished knitwear. In the device according to the invention, in which the course of the warped fiber structure aem last active transport element to the knitting point is the same, the disadvantage of different stresses in the fiber structure is avoided. The same course of the fiber composites means that the length of the fiber structure between the last active transport element and the knitting point and the number and size of the deflections in this area are the same. Advantageously, the last active transport element is arranged so that in the area up to the knitting no further deflection of the fiber strand more.

As "active Transportelemenf in the sense of this patent application components are called, which can exert a force in the transport direction on the fiber structure and thus can affect the speed of the fiber structure defined. The last active transport element for the warped fiber strand can be designed differently. It may, for example, be an output roller pair of the drafting system, a delivery mechanism or even an air nozzle. The same geometry of the course of the warped fiber structure in the areas before two knitting points causes the friction ratios for the fiber dressings to be substantially the same, so that the fiber dressings, when supplied at the same speed on the active transport element, also substantially at the knitting point have the same voltages.

In an embodiment of the invention, it is advantageous if the speed of the warped fiber structure can be varied at the last active transport element in front of the knitting point. By slightly varying the speed, the tension of the fiber structure at the knitting point can be changed. This is advantageous in the production of knits with patterns or with different types of stitches. It may be advantageous to make the speed of several fiber composites of the last active transport element the same, for example at every second or third knitting point. The speeds of the fiber composites at the intermediate knitting points may be slightly higher or lower, so that there is a different tension at these knitting points.

In a further embodiment of the invention, it may also be advantageous that the speed of the distorted fiber structure during the manufacturing process of the knitted fabric is changeable. In this way, a regulation of the tension of the fiber structure at each knitting point could be realized. The embodiment in which the last active transport element is the pair of output rollers of the drafting system has the advantage that no additional active transport element is required after the pair of output rollers of the drafting system. So that the course of the distorted fiber structure before each knitting point is the same, it is necessary to use individual drafting systems. In the case of a circular knitting machine as a knitting device, it is advantageous to arrange the drafting systems in the radial orientation around the needle cylinder and to let the fiber composites extend from the drafting devices radially inwards to the knitting points.

The use of an additional active transport element between the pair of output rollers of the drafting system and the knitting point, such as a delivery roller pair containing delivery mechanism or an air nozzle, has the advantage that each multiple drafting can be combined to form a drafting group and thereby the drive and the arrangement of the drafting easier becomes. In addition, the drafting units can be positioned at a greater distance from the knitting device. The accessibility of the device and the space utilization can be optimized. The course of the distorted fiber structure after the pair of output rollers of the drafting system now has no negative impact on the knitwear, since the warped fiber structure is provided by the last active transport element in front of the knitting point again with a defined speed. Deflections and / or different distances between the pair of output rollers and the last active transport element can no longer produce different voltages of the fiber composites at the knitting points. The distances between the drafting system and the last active transport element in front of the knitting device can now be chosen in principle as it is advantageous for the utilization of local conditions at which the device is to be set up. The distance is basically limited only by the strength of the warped fiber structure. In the transport of the fiber structure over long distances, it may also be advantageous to arrange a plurality of swirl devices in succession, so that the transport strength of the warped fiber structure is maintained up to the knitting device.

Further advantages and features of the invention will become apparent from the following description of some embodiments.

Show it:

FIG. 1 shows a diagrammatically represented side view of a device according to the invention with two different variants of drafting systems, FIG. 2 shows a plan view in the direction of the arrow II of FIG. 1 of the device according to the invention,

FIGS. 3 to 6 show different variants of active transport elements for the warped fiber structure,

Figure 7 is a view similar to Figure 2 on another embodiment of the device.

A device for spinning knitting is very schematically illustrated in Figures 1 and 2, with which a knitted fabric is produced without the "detour" of the classical yarn production.The device contains as an essential component a knitting device 1, which are formed by a commercially available flat or circular knitting machine In the figures, only one needle cylinder 2 of a circular knitting machine is indicated, and similarly, a flat knitting machine can be used just as well. which are produced in drafting units 4 and 5 in the vicinity of the Nadelzyfinders 2. There are two different variants of drafting units 4 and 5 shown simultaneously to illustrate the preferred variants.The drafting units 4 are as three-cylinder drafting and the drafting 5 as four-cylinder Strec executed. Depending on the height of the required distortions and the type of fiber material processed, a drafting device 4 or drafting device 5 may be advantageous. In practice, of course, only one type of drafting devices 4 or 5 is used on a knitting device 1, that is to say either only three-cylinder drafting systems or only four-cylinder drafting systems. A three-cylinder drafting system 4 is advantageous if the fiber structure 6 to be distorted is fed to the drafting unit 4 in the form of a sliver or roving from a flyer bobbin 7. A four-cylinder drafting system 5 is advantageous if the fiber structure 6 to be distorted is supplied from a can 8 in the form of a sliver and warped with a very high distortion.

Each drafting system 4, 5 contains a plurality of pairs of rollers, each consisting of a drivable lower roller 9 and a resiliently pressed-on upper roller 10. The fiber structure 6 to be distorted is warped in the transport direction A by the roller pairs which can be driven with increasing peripheral speed until a distorted fiber structure 3 of the desired fineness is present at the exit roller pair 11 of the drafting system 4 or 5. To guide the fiber structure in the drafting system 4, 5, one or more pairs of rollers in be assigned in a known manner Führungsriemchen 12. In Figure 2 it can be seen, einei a plurality of juxtaposed drafting units 4 and 5 are each combined to form a drafting group 13 and 14 respectively. The two drafting unit groups 13 and 14 are arranged on opposite sides of the knitting device 1 and can each contain, for example, 12, 24 or even 48 defaulting points. For the sake of simplicity, only five warped fiber composites 3 are shown in FIG. 2 for each drafting group group 13, 14. The lower rollers 9 of each roller pair in a drafting group 13 or 14 are designed as a continuous sub-cylinders and can each be driven by a common drive. For purposes of illustration, the top rollers 10 of the drafting units 4 and 5 are omitted in Figure 2.

The warped fiber structure 3 produced on the output roller pair 11 of the respective drafting system 4 or 5 is fed in the transporting direction A to a knitting point 15 on the needle cylinder 2 of the knitting device 1. The knitting device 1 in this case has drive means, not shown, which drive the needle cylinders 2 containing the knitting needles 16 in a manner known per se and process the supplied fiber bundles 3 into a knitted fabric.

Between the output roller pair 11 and the knitting point 15 at least one active transport element 17 is arranged for the warped fiber structure 3. The active transport element 17 can, as indicated in FIGS. 1 and 2, consist of a delivery mechanism 18 which, for example, consists of a pair of rollers. Depending on the distance, one or more swirl devices 19 are arranged between the pair of output rollers 11 of the drafting system 4 or 5 and the active transport element 17, which give the fiber structure 3 consisting essentially of parallel fibers sufficient strength for transport to the knitting point 15. It is advantageous to give the fiber structure 3 a false twist, which dissolves again in the knitting point 15, so that the fibers are substantially integrated in a parallel position to each other in the knit fabric produced. If the distance between the active transport element 17 and the knitting point 15 is smaller than the average fiber length of the warped fiber structure 3, the fiber structure 3 can be fed directly to the knitting point 15. In particular, if this distance is greater than the mean fiber length, it may be advantageous to provide between the active transport element 17 and the knitting point 15, a further twisting device 20, which gives the warped fiber structure 3 sufficient for transport strength. As swirl means 19 and 20, so-called spin tubes, each having a pneumatically acting swirl nozzle, can advantageously be used. Depending on the requirements, it may be favorable, the swirl devices 19 and 20 in such a way that the twist generated in the distorted fiber structure 3 is directed in the same direction or in opposite directions.

Depending on the distance between the pair of output rollers 11 and knitting point 15, a warped fiber structure 3 may also be assigned a plurality of active transport elements 17 in an embodiment which is not shown.

According to the invention, it is provided that the geometry of the course of the warped fiber structure 3 in a region 21 in front of each knitting point 15 is the same. The region 21 extends from the knitting point 15 to at least the last active transport element 17 for the distorted fiber structure 3. The voltage differences in the individual fiber assemblies 3 caused by the different geometrical relationships between the pair of output rollers 11 and the active transport element 17 can occur the active transport element 17 does not propagate to the knitting point 15 and thus do not cause any quality problems with the knitted fabric produced. All warped fiber composites 3 are provided in the transport direction A last active transport element 17, for example by the delivery mechanism 18, with a defined speed and thus supplied to the knitting device 1. The transport elements 17 are preferably arranged on a circle concentric with the needle cylinder 2.

To produce a simple knitwear, it is advantageous that the speed of the warped fiber structure 3 on the last active transport element 17 in front of all knitting points 15 of the knitting device 1 is the same. As a result, the tension of the fiber structure 3 at each knitting point 15 is the same size, since the geometric Veήauf the fiber structure 3 between the last active transport element 17 and the knitting device 1 is the same. The distance between the knitting point 15 and the upstream active transport element 17 and the number and type of deflections of the fiber structure 3 in the region 21 are the same.

It is advantageous that the speed with which the distorted fiber structure 3 is processed in the knitting point 15 by the knitting needles 16 is slightly above the speed of the fiber structure 3 on the active transport element 17. The speed of the fiber structure 3 on the active transport element 17 should in turn be slightly above the speed of the distorted fiber structure 3 on the output roller pair 11. This slight increase in speed in the transport direction A should not further distort the fiber structure 3, but merely serves to keep the warped fiber structure 3 slightly under tension is and thereby better transportable between the pair of output rollers 11 and the knitting point 15.

Depending on the type of knitted fabric produced, it may be necessary to change the tension of the fiber structure 3 at some knitting points 15. This can preferably be achieved in that the speed of the warped fiber structure at the last active transport element 17 in front of the knitting point 15 is variable. For example, it may be advantageous to supply each second fiber structure 3 on the circumference of the needle cylinder 2 with a slightly higher voltage. In such a case, the different speeds are set once on the active transport elements 17 or on their drives and then remain unchanged during the manufacturing process of the knitwear. In an embodiment, however, it may also be advantageous to permanently change the speed of the distorted fiber structure 3 during the production process of the knitwear and to regulate the tension of the warped fiber structure 3 at the knitting point 15. It may be advantageous to arrange a sensor between the last active transport element 17 and the knitting point 15 which detects the actual value of the voltage and can serve as the basis for the regulation of the speed at the active transport element 17.

With the aid of FIGS. 3 to 6, a few variants of active transport elements 17 are described below. FIG. 3 shows an active transport element 17 designed as delivery mechanism 318. The delivery mechanism 318 consists of two rollers 322 and 323, which form a pair of rollers. The roller 322 may be a driven steel roller to which a pressure roller 323 provided with an elastic cover 24 is pressed. The drive of the roller 322 can for example be done directly by a small electric motor. A change in the speed of the distorted fiber structure 3 at the delivery 318 is then very easy by changing the speed of the electric motor at each delivery 318 possible. If, for example, the rollers 322 of all delivery mechanisms 318 are driven by a belt that runs essentially concentrically with the needle cylinder 2, the speed of the warped fiber structure 3 at the delivery mechanism 318 can be changed by selecting a specific cover 24 on the pressure roller 323. The change in the hardness of the cover 24 of the pressure roller 323 causes a slightly changed speed of the distorted fiber structure 3 at the same speed of the roller 22.

In the variant of the delivery mechanism 418 shown in FIG. 4, a driven roller 422 is assigned two pressure rollers 423, which are looped around by a belt 25. These Embodiment is advantageous because the diameter of the pressure rollers 23 can be greatly reduced without the transport properties for the warped fiber structure 3 and the service life of the pressure rollers 423 deteriorate. Due to the smaller diameter of the pressure rollers 423 space can be saved, so that the delivery 418 can be much closer to the knitting point 15 as the delivery 318 arrange.

FIG. 5 shows an active transport element 17 designed as delivery mechanism 518. The delivery mechanism 518 consists of two conical rollers 522. It may be advantageous to carry out one of the rollers 522 as a pressure roller with an elastic cover. Alternatively, both rollers 522 may have an intermeshing, corrugated structure which meshes with one another similar to a toothing and thereby transports the distorted fiber structure 3. At a constant speed of the rollers 522, the speed of the supplied fiber structure 3 can be changed by the distorted fiber structure 3 is displaced in the axial direction of the rollers 522 along the double arrow B. The speed of the distorted fiber strand 3 can be increased by a shift in the region of the larger diameter of the roller 522.

FIG. 6 shows an alternative embodiment of an active transport element 17 as an air nozzle 26. The air nozzle 26 has a transport channel 28 for the warped fiber structure 3. There is provided at least one injection channel 27, which opens into the transport channel 28 and is inclined in the transport direction A of the fiber structure. Preferably, a plurality of injection channels 27 are arranged on the circumference of the transport channel 28. The injection channels 27 are connected to a compressed air source, not shown, and can be acted upon via a supply line 29 with compressed air. Due to the inclination of the InjektionskanäJe 27, the transport effect of the air nozzle 26 can be varied. In addition, the transport effect of the air nozzle can be achieved by changing the pressure of the air flowing through the injection channels 27. A higher pressure in the supply line 29 causes a higher outflow velocity of the air from the injection channels 27, whereby the warped fiber strand 3 is transported through the active transport element 17 at a higher speed. It can be provided that the pressure in the supply line 29 is changed depending on the tension of the warped fiber structure 23 between the air nozzle 26 and the knitting point 15 and the tension of the distorted fiber structure 3 can be regulated thereby. In an embodiment, the injection channels 27 can also be arranged so that the air nozzle 26 simultaneously gives the fiber structure 3 a twist. FIG. 7 shows a variant of an apparatus for producing a knitted fabric, in which a multiplicity of individual drafting units 30 are arranged on the knitting device 1. The geometry of the course of the warped fiber structure 3 in a region 21 in front of each knitting point 15 is again the same. In contrast to the apparatus of Figures 1 and 2, in Figure 7, however, the last active transport element 17 for the warped fiber strand 3, the pair of output rollers 11 of the drafting 30. On the periphery of the needle cylinder 2 is shown in Figure 7 by way of example the arrangement of seven single drafting 30 and the Course of the corresponding warped fiber composites 3 indicated. Depending on the size of the needle cylinder 2, it is advantageous to arrange as many individual drafting units 30 on the circumference of the needle cylinder 2. The individual drafting systems 30 can be designed as a three- or four-cylinder drafting system depending on the nature of the fiber structure 6 to be distorted.

It is advantageous that Rotationsie axis of rotation of the pair of output rollers 11, which forms the last active transport element 17 for the warped fiber structure 3 in the variant of Figure 7, is oriented parallel to the axis of rotation of the needle cylinder 2. The parallel alignment allows a particularly space-saving arrangement of the drafting units 30 on the circumference of the needle cylinder 2, so that a large number of drafting units 30 can be provided. In addition, the distance between the pair of output rollers 11 and the knitting point 15 can be kept as small as possible. Nevertheless, it will usually be necessary to arrange a swirling device 20 between the pair of delivery rollers 11 and the knitting point 15, since in most cases the distance is greater than the average length of the fiber in the warped fiber structure 3.

Claims

claims

Device for producing knitwear comprising knitting needles (16) and at least two knitting points (15), each knitting point (15) being preceded by a drafting device (4; 5; 30) for producing a distorted fiber structure (3) characterized in that the geometry of the course of the distorted fiber structure (3) in a region (21) in front of each knitting point (15) is the same, the region (21) extending from the knitting point (15) to at least the last one active transport element (17) for the warped fiber structure (3).

2. Apparatus according to claim 1, characterized in that the last active transport element (17) for the warped fiber structure (3) is a pair of output rollers (11) of the drafting system (30).

3. Device according to claim 1, characterized in that the last active transport element (17) for the warped fiber structure (3) is a delivery mechanism (18; 318; 418; 518).

4. Device according to one of claims 1 to 3, characterized in that the knitting device (1) comprises a needle cylinder (2), and that the axis of rotation of the last active transport element (17) for the warped fiber structure (3) parallel to the axis of rotation of the needle cylinder (2)

5. The device according to claim 1, characterized in that the last active transport element (17) for the warped fiber structure (3) is an air nozzle (26).

6. Device according to one of claims 1 to 5, characterized in that the speed of the warped fiber structure (3) on the last active transport element (17) in front of the knitting point (15) is variable.

7. Apparatus according to claim 6, characterized in that the speed of the distorted fiber structure (3) during the manufacturing process of the knitwear is variable.

8. Device according to one of claims 1 to 6, characterized in that the speed of the warped fiber structure (3) on the last active transport element (17) before several knitting points (15) of the knitting device (1) is the same.