GB1581845A - Elastic web of warp knitted material - Google Patents

Description

(54) ELASTIC WEB OF WARP KNITTED MATERIAL (71) We, GOLD-ZACK WERKE AG, a body corporate organised and existing under the laws of the Federal Republic of Germany, of Gold-Zack-Strasse 2-4, 4020 Mettmann, Federal Republic of Germany, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following state- ment:: The present invention relates to an elastic web of warp knitted material consisting, on the one hand, of a number of stitch-forming threads (stitch threads) of non-elastic material, which form wales extending in the longitudinal direction of the material and are made up of interlooping stitches, and on the other hand, of two groups of threads (hereinafter called weft threads) of elastomeric material, which extend as wefts between the wales and in the transverse direction of the knitted material, the weft threads of the first group comprising exclusively pick insertions having a short transverse run and each continuously changing over from one side of the associated wale to the opposite side, whereas the weft threads of the second group, which have the same lay as the stitches, have a longer transverse run extending over at least two wales.

The two groups of elastomeric weft threads produce an elastic web of knitted material which can be stretched both in the longitudinal direction and the transverse direction. Since the weft threads of one of the groups each wind from one side of its associated wale to the opposite side thereof, longitudinal stretch of the knitted material is ensured. On the other hand, the second group of weft threads, having a considerably longer transverse run, determines the stretch characteristics in the transverse direction of the knitted material. These two systems consisting of elastomeric weft threads enable the required stretch characteristics to be obtained.

If, in this knitted material (German Patent Specification 692 982), the weft threads, responsible for the transverse elasticity, are reversed after a transverse run across two wales, a satisfactory degree of stretch of the material in this direction cannot be achieved. If a longer transverse run, extending over at least three wales, is used (Austrian Patent Specification 221 698), then there is obtained a material that is prone to develop defects and in which, unfortunately, the transverse stretch may not be exploited to a great or its fullest extent, since in this knitted material cross-over areas are created between the two weft-thread systems, the elastomeric material of which has high surface friction.The stretch and, in particular, the contraction of the weft threads in one of the group is prevented by friction of the threads in the other group, so that defects eventually develop in such knitted materials after they have been worn and washed over fairly lengthy periods. These defects are manifested by displacement of the stitches leading to the creation of an uneven material pattern consisting of areas that are tighter or looser than the average. In extreme cases, knots, projecting from the surface of the knitted material, are formed and these consist of the obstructed elastomeric fibres which, after having been heavily stretched, are unable to contract and return to their original positions. These knots form areas of pressure when items of clothing made of such material are being worn.When such clothing is being put on and taken off, heavy localized stretching occurs in the areas where the material is gripped by the finger-tips of the wearer. In addition, in the case of such materials having a long transverse run, considerably greater lengths of thread have to be worked into the material without it being possible fully to exploit the stretch characteristics inherent in the high quantity of material used.

There is thus a need for a material which is very elastic in the longitudinal and transverse directions and which, even when heavily stretched, remains free from defects and keeps its regular attractive pattern.

According to the invention, there is provided an elastic web of warp knitted material consisting, on the one hand, of a number of stich-forming threads (stitch threads) of nonelastic material, which form wales extending in the longitudinal direction of the material and are made up of interlooping stitches, and on the other hand, of two groups of threads hereinafter called (weft threads) of elastomeric material, which extend as wefts between the wales and in the transverse direction of the knitted material, the weft threads of the first group having a short transverse run and each continuously changing over from one side of the associated wale to the opposite side, whereas the weft threads of the second group, which have the same lay as the stitches, have a longer transverse run extending over at least two wales, wherein the total extent of the transverse run of the weft threads of the second group is divided stepwise into at least two portions and a short return transverse jump lies between each two of these portions. The provision of this interposed return jump in the transverse run of the long-bond weft thread system avoids troublesome locking points due to crossing over with the weft threads of the other elastomeric material. However, when the knit is heavily stretched, weft-thread material is still able to move from its forward portion in the transverse run into the rearward portion by way of the S-shaped reversal zone in the thread, without its return movement being rendered difficult or even impeded in the relaxed initial condition. Surprisingly, it has been found that even heavy stretching of the knitted material does not cause permanent displacement of threads in the knit.No displacement of stitches occurs that leads to the formation of gaps in the knit, and furthermore, no knots, that project in a troublesome manner from the surface of the material, are formed.

Despite the high elasticity, only relatively small lengths of thread are required in the weft thread material of the second group having the long transverse runs. Despite the total transverse runs covering a plurality of wales and the fact that such long-bond weft threads are associated with each wale, these weft threads occur severally, and not collectively side-by-side, in the zone of these transverse runs.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which: Figures 1 to 3 show pattern diagrams of the three types of thread used for forming an elastic web of warp knitted material according to the invention, Figure 4 shows the pattern diagram that results when all of the threads of the first type are brought into one portion, but the other two types of thread, for reasons of clarity, are brought into only one sample, and Figure 5 shows, in one portion, the stitch diagram of the knitted material resulting from the patterning arrangement shown in Figure 4.

The warp knitted material in accordance with the invention is produced on a double-rib machine to which the details in the patterns of Figures 1 to 4 refer.

Figure 1 shows the pattern of a thread 11, forming the stitches of warp knitted material 10 seen in Figure 5, a plurality of these threads, as seen in Figures 4 and 5, being worked sideby-side and extending in the same direction as each other each time. The thread material used is polyamide yam. The points 12 illustrate the positions of the customary latch needles on the bar of a double-rib machine, which needles are vertically movable in known manner for the purpose of forming the stitches. Each horizontal row 13 of these points 12 illustrates the laid stitches which run off at the individual latch needles at the same time and which form a row 14 of stitches which, as can be seen from Figure 5, consists of stitches 15 and 16 aligned with each other in the transverse direction of the knitted material.All of the stitch threads 11 are uniformly reciprocated in relation to the symbolically indicated latch needles 14 during the individual working phases 13. For this purpose, these stitch threads 11 are passed through the apertured needles of a common transversely movable guide-bar of the doublerib machine. The transverse movement of this guide bar on the one hand and the vertical movements of the symbolically indicated latch needles 12 on the other result in movement of the stitch threads 11 that is shown technically in Figure 1 and in stitch form in Figure 5. In these Figures and in accordance with the normal technical practice, the gaps between the latch needles 12 are indicated by the numbers 0, 2, 4 and 6 for the purpose of indicating the thread movement on a numerical basis.

It will be seen from Figure 1 that the guide bar for the stitch threads 11 runs upwards in the gaps between the needles and in the direction in which the material is being formed, in the following manner: 2-0/2-4/4-2/4-6/4-2 /2-4// During this movement and as shown by the bottom row 14 of stitches in Figure 5 and the bottom horizontal row 13 in Figure 1 and Figure 4, where the above-mentioned working phase of the guide bar is shown in relation to the bar of the machine that is provided with latch needles, closed stitches 15 are formed, whereas in the second row 14 of stitches seen in Figure 5 and the second row 13 of points seen in Figures 1 and 4, open stitches 16 are created, whereafter in the following rows 14 and 13 respectively first two closed stitches 15, 15 are formed and then an open stitch 16 again and finally another closed stitch 15. After six rows of stitches as indicated by the arrow R in Figures 1 and 5, the pattern run R for the knitted material 10 is completed, and the thread movements are repeated. It can also be seen from Figure 1 that the lay of the stitch thread is of mirror-image form in relation to the axis of symmetry indicated by the dash-dot horizontal line 17, apart from the shape of the stitch. In relation to the line of symmetry 1 7, the stitch thread 11 runs from the fourth latch needle, counting from the right, over a diagonal portion 18 to the third latch needle, to the right thereof, where of course different stitch shapes 15 and 16 are formed to each side of this line of symmetry 17.Between the third and the second and between the fifth and the sixth horizontal working phases, the stitch thread 11 is worked in an invariable manner with the third latch needle. Then however, in a mirror-image arrangement in relation to the line of symmetry 17, a diagonal run 18 again occurs to the second latch needle disposed to the right thereof.

In this mode of operation, interlooping stitches, extending in the longitudinal direction of the knit, are created in the knitted material 10 seen in Figure 5. These longitudinally extending interlooping stitches are each formed, in the various working phases 13, by the same latch needle in the bar of the double-rib machine, and are referred to as wales 19.

For forming the knitted material 10, use is also made of what are called herein "weft threads", which consist of elastomeric material but belong to two basically differently operating groups 20 and 21 of weft threads.

The differing run of these two groups of weft thread 20 and 21 shown in Figures 2 and 3 respectively. This expression "weft thread", borrowed from the weaving industry, signifies that these threads, which do not form stitches, are arranged like wefts in the transverse direction of the material and between the abovementioned longitudinally extending wales 19.

The weft thread 21 belonging to the first group is characterized by its being formed exclusively of short transverse runs 22 as shown in Figure 3. Each of these weft threads runs only from one side of a wale to its opposite side and back again. In relation to the needles gaps 0 and 2 shown in Figure 3, such a weft thread 21 is worked in the following manner: 2-2/0-0/2-2/0-0/2 -2/0-0//.

For this purpose all of the weft threads 21 belonging to this group are of course drawn in a standard third guide bar of the double-rib machine, which guide bar, on each occasion, executes a reciprocatory movement over a distance equivalent to a latch needle so that the thread is laid below a needle. It will be understood that each weft thread 21 of this group is worked in each needle gap when a tight knit is required. Thus, in this third guide bar too, each apertured needle receives such a weft thread 21. Only one such weft thread 21 is shown in the thread pattern of Figure 4 and the stitch pattern of Figure 5, this being simply for the purpose of making the drawings easier to read. The run of the thread must be imagined to occur at each wale 19.The group consisting of these weft threads 21 ensures that the knitwear can stretch in the longitudinal direction, as illustrated by the arrows 29 in Figure 3.

The weft thread 20 of the second group however has, at least in places, a several times longer transverse run as can be seen in the pattern diagram in Figure 2, here a special pattern is obtained.

The total extent 23 of the transverse run covers the distance from the needle gap 0 to the needle gap 6 and, as can be seen from Figure 5, covers the intermediate three wales 19. However, this total stretch 23 is at no point completed as a single unit but occurs stepwise in two portions 24 and 25. These two portions occur in the bottom and third from the bottom rows of stitches 14 seen in Figure 5, which rows correspond to the working phases in a hoiizon- tal row 13, seen in Figure 2. In between however, in the second row 14, which corresponds to the second working phase 13 in Figure 2, there occurs a short return transverse run 26, i.e. the thread is laid in the opposite direction below a needle. Thus, a run for this complete stretch 23 is obtained that is in the form of a doubled S.These transversely extending portions 24 and 25 run right through without any intermediate holding points at the wales 19.

Thus, the first transversely extending portion 24 is held only by its end arcuate parts 27 and 27' on the first two wales 19 seen in Figure 5, and it can therefore stretch transversely in an unrestricted manner over its intermediate part if the knitted material is stressed. This also applies in the case of the other portion 25 of the transverse run where the second and third wales 13 from the left in Figure 5 are engaged by the associated end arcuate parts 28 and 28'.

There are no intermediate obstacles which, despite the long total stretch 23, could impede the stretching and contraction of these thread portions. Thus, displacement of the threads is effectively prevented. It will be understood that the abovementioned total stretch 23 could be greater, though the insertion of the weft thread 20 would then be divided up into a correspondingly larger number of portions 24 and 25 with corresponding short return portions.

As shown in Figure 2, the weft thread 20 is also laid in a mirror-image arrangement in relation to the axis of symmetry 17 indicated by the dash-dot line. As regards this fourth working phase, the run of the thread in the third and fifth on the one hand and in the second and sixth on the other is the same in each case.

There then follow transverse runs of the same extent in two portions 25 and 24 which, as shown in Figures 4 and 5, always connect two adjacent wales, and a short return run 26. The lay is still in the opposite direction to give the mirror-image arrangement.

The short return runs 26 in opposite directions cover only one single wale 19, as can be seen from Figures 4 and 5, and they therefore do not contribute to the elasticity of the knitted material in the transverse direction. They serve the purpose of locally securing the weft thread 20 to the wale by means of the two arcuate parts 27' and 23 for example in the case of the second wale from the left in Figure 5. However, as shown by the symmetrical ararrangement seen in Figure 2, a total of four transverse runs 24, 25, 25 and 24 of a weft thread is available within a pattern unit R for providing stretch in the transverse direction of the knitted material 10. This is indicated in Figure 2 by corresponding doubleheaded arrows 30.

The above-mentioned mode of working the weft thread 20 can be indicated technically, by reference to the patterns in Figures 2 and 4, in the following manner: 6-6/2-2/4-4/0-0/4-4/2-2//.

Although, for reasons of clarity, only one sample for the weft thread 20 is shown in Figures 4 and 5, it will be understood that such a weft thread 20 can be arranged in the gap associated with each wale and can be worked in a corresponding parallel manner. In this case all the apertured needles of an associated second guide bar are provided with such weft threads.

Instead of being produced on the above-mentioned double-rib machine, the knitted material in accordance with the invention could of course be made on a chain-type knitting machine provided with needles of different form to latch needles.

WHAT WE CLAIM IS:- 1. An elastic web of warp knitted material consisting, on the one hand, of a number of stitch-forming threads (stitch threads) of nonelastic material, which form wales extending in the longitudinal direction of the material and are made up of interlooping stitches, and on the other hand, of two groups of thread (hereinafter called weft threads) of elastomeric material, which extend as wefts between the wales and in the transverse direction of the knitted material, the weft threads of the first grouping having a short transverse run and each continuously changing over from one side of the associated wale to the opposite side, whereas the weft threads of the second group, which have the same lay as the stitches, have a longer transverse run extending over at least two wales, wherein the total extent of the transverse run of the weft threads of the second group is divided stepwise into at least two portions, and a short return transverse jump lies between each two of these portions.

2. A web of warp knitted material according to claim 1, wherein within a pattern unit (R), weft threads of the second group, which extend transversely over a total stretch of three wales, run, in a first row of stitches, over only two wales, run back to an extent equal to one wale in the following row of stitches, and continue to run transversely again over two wales in the original direction, in a further third row of stitches.

3. A web of warp knitted material according to claim 1 or claim 2, wherein, within the first half of a pattern unit (R), the weft threads of the second group having a long transverse run, extend only in one direction transversely to the web of warp knitted material, except for a short median return jump, and within the second half of the pattern unit are arranged in the web of warp knitted material in an opposite mirror-image form.

4. A web of warp knitted material according to any one of claims 1 to 3, wherein the runs of the stitch threads and of the two groups of weft threads in the web of warp knitted material are disposed in a mirror-image arrangement in relation to an imaginary limiting line between the first and second halves of the pattern unit (R), this line constituting the axis of reflection.

5. An elastic web of warp knitted material substantially as hereinbefore described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (5)

**WARNING** start of CLMS field may overlap end of DESC **. transverse runs 24, 25, 25 and 24 of a weft thread is available within a pattern unit R for providing stretch in the transverse direction of the knitted material 10. This is indicated in Figure 2 by corresponding doubleheaded arrows 30. The above-mentioned mode of working the weft thread 20 can be indicated technically, by reference to the patterns in Figures 2 and 4, in the following manner: 6-6/2-2/4-4/0-0/4-4/2-2//. Although, for reasons of clarity, only one sample for the weft thread 20 is shown in Figures 4 and 5, it will be understood that such a weft thread 20 can be arranged in the gap associated with each wale and can be worked in a corresponding parallel manner. In this case all the apertured needles of an associated second guide bar are provided with such weft threads. Instead of being produced on the above-mentioned double-rib machine, the knitted material in accordance with the invention could of course be made on a chain-type knitting machine provided with needles of different form to latch needles. WHAT WE CLAIM IS:-

1. An elastic web of warp knitted material consisting, on the one hand, of a number of stitch-forming threads (stitch threads) of nonelastic material, which form wales extending in the longitudinal direction of the material and are made up of interlooping stitches, and on the other hand, of two groups of thread (hereinafter called weft threads) of elastomeric material, which extend as wefts between the wales and in the transverse direction of the knitted material, the weft threads of the first grouping having a short transverse run and each continuously changing over from one side of the associated wale to the opposite side, whereas the weft threads of the second group, which have the same lay as the stitches, have a longer transverse run extending over at least two wales, wherein the total extent of the transverse run of the weft threads of the second group is divided stepwise into at least two portions, and a short return transverse jump lies between each two of these portions.

2. A web of warp knitted material according to claim 1, wherein within a pattern unit (R), weft threads of the second group, which extend transversely over a total stretch of three wales, run, in a first row of stitches, over only two wales, run back to an extent equal to one wale in the following row of stitches, and continue to run transversely again over two wales in the original direction, in a further third row of stitches.

3. A web of warp knitted material according to claim 1 or claim 2, wherein, within the first half of a pattern unit (R), the weft threads of the second group having a long transverse run, extend only in one direction transversely to the web of warp knitted material, except for a short median return jump, and within the second half of the pattern unit are arranged in the web of warp knitted material in an opposite mirror-image form.

4. A web of warp knitted material according to any one of claims 1 to 3, wherein the runs of the stitch threads and of the two groups of weft threads in the web of warp knitted material are disposed in a mirror-image arrangement in relation to an imaginary limiting line between the first and second halves of the pattern unit (R), this line constituting the axis of reflection.

5. An elastic web of warp knitted material substantially as hereinbefore described with reference to the accompanying drawings.