EP1187947B1 - Method for producing multiaxial warp knit fabric - Google Patents

Abstract

A method for producing multiaxial warp knit fabrics with extended threads in longitudinal, transverse and diagonal directions as a result of direct insertion of the diagonal threads as weft sections onto backs of rising needles of needle bars. The method includes simultaneously inserting at least two diagonal thread systems contrarily as part wefts for each needle bar on a right/right warp knitting machine.

Description

Technical field

The invention relates to a method for producing multiaxial warp knitted fabrics with stretched threads in the longitudinal, transverse and diagonal direction by direct Entry of the diagonal threads as weft sections on the back of the ascending Needles. The textile structures produced with the process are due to their high stability and strength in different directions Reinforcement in composite materials, for example in automobile construction, rail vehicle construction and the aerospace industry.

State of the art

The production of muttiaxial warp knitting by incorporating reinforcing Threads as weft, warp and diagonal threads are already known. In DE-OS 33 04 For example, 345 is a warp knit with a normal warp knit as Goods reason and described in these inserted reinforcing threads at which Weft threads run parallel to each other and each between two mesh heads of successive rows of stitches are arranged and in addition two sets of diagonal threads are provided, each alternating between two mesh heads run in the direction of successive rows of stitches. At this Reinforcement threads are available in warp, weft and diagonal direction, that are not pierced by the knitting needles. All reinforcement threads are arranged at an angle of 45 ° to each other, but due to the process cannot be changed.

Also known is a special warp knitting machine for processing multiaxial fabrics, in which up to seven thread layers are suspended in a transport chain (90 ° / ± diagonal / 90 ° / -diagonal / 90 ° / + diagonal / 90 °) and in the area of the active site be consolidated by a warp knit. Immediately before the point of action a 0 ° thread system can be placed as the last thread layer. The knitting process however, requires piercing the densely layered thread layers, which leads to Moving the threads leads. A reduction in the firmness and an uneven, the consequences are poor structural density (Melliand textile reports 11/86, pp. 804 to 806).

With the sewing machine, type Malimo, with multiaxial weft insertion is the production of multi-axial knitted fabrics possible, for example with a combination of thread layers from 0 ° / -90 ° / -45 ° / -90 ° / - + 45 ° with angular deviations from 1 to 5 °, d. H. the Weft threads are not exactly parallel (warp knitting practice 2/94, p.15 to 17).

With the multiaxial knitting technique for the production of technical textiles on one Right / left flat knitting machine is the multiaxial thread entry through a combination of threads in the directions 0 ° / 90 ° / ± 45 ° realized (ITB Nonwovens - technical textiles 1/95, p.44 to 45). The specialty of this knitted fabric is in that the diagonal and vertical (0 °) threads on the front and Alternate the back of the goods after every other row. The thread course for the warp and diagonal threads from the front to the back of the fabric is by additional drives for the feed elements, one to control the crossing movement and one to control the offset movement, the carousel-like is carried out, realized. This integration technique is primarily intended for composite materials occurring delamination can be prevented.

A biaxial knitting technique and a biaxially reinforced multi-layer knitted fabric are over known from DE 44 19 985 A1. On a right / right flat knitting machine a total of five weft thread systems are entered crossing at right angles (90 ° / 0 ° / 90 ° / 0 ° / 90 °). Due to the arrangement of the thread layers (0 ° / 90 °) there are none Multi-axial knitted fabrics can be produced. The 0 ° thread layers are also driven out Pierced needles, which leads to the same disadvantages as the Special warp knitting machine.

In addition, several patents (DD 268 720, DD 268 721, DD 268 722, DD 268 723, DD 268 724, DD 256 885) Variants for the implementation of multiaxial devices, especially known for sewing machines with which one Quality improvement of multiaxial fabrics with reduced mechanical engineering Effort and a variable design by adding finite Thread sections are to be achieved from thread storage cartridges.

In the case of the techniques that work on the basis of the thread groups, they form In principle, 0 ° thread layers always cover the top layer, which means that the multilayer structures the isotropy of the composite is impaired. A part of the known multiaxial structures has thread systems crossing at right angles, with which the requirements regarding fiber angle (not greater than 45 °) are not met can be. The known devices for inserting sheets of thread in Transport chains allow the laying angle to be varied within certain limits the diagonal threads, but not when the machine is running.

Presentation of the invention

The invention specified in claim 1 is based on the problem of a method for the production of knitted reinforcement structures with a multiple, variable, to develop multiaxial thread course with which in the area of diagonal and 90 ° threads with the machine running the thread angle depending on the required Force lines can be changed. The aim is to pierce layers of thread or the piercing of threads can be avoided in order to produce at low cost to ensure.

This problem is solved by the features listed in claim 1. Advantageous developments of this method according to the invention are the subject of the respective subclaims.

The advantages achieved with the invention are in particular that with the The right / right warp knitting machine is used to insert the weft in line with the stitch rows can, with the simultaneous opposite insertion of the diagonal threads on the front and rear needle bar with four diagonal thread systems with little effort for each complete row of stitches. Another advantage is that the 0 ° threads are fed directly between the opposite weft threads and be involved. Piercing the threads with this procedure excluded, so that better substance utilization compared to multiaxial forfeited fabrics is possible. Due to the direct shot entry there is no previous one Fabric production (hanging the thread sheets placed at an angle in transport chains) required so that direct control of the displacement path of the weft threads in the area of the effective zone. In this way it is possible to change the laying angle to change the diagonal threads according to the line of force. 90 ° threads can also be used can be brought into a 0 ° position, which means differentiated layer thicknesses in different sequence can be realized.

In addition, the binding elements create a rough, three-dimensional Right / right warp knit structure the multiaxially layered threads in the Z direction significantly increased and thus the resistance to delamination considerably improved.

Brief description of the drawings

Fig. 1

die schematische Darstellung der Wirkstelle einer Rechts/Rechts-Kettenwirkmaschine zur Durchführung des erfindungsgemäßen Verfahrens,

Fig. 2

einen Schnitt durch ein Rechts/Rechts Kettengewirke gemäß Fig. 1,

Fig. 3

die schematische Darstellung einer Draufsicht auf das Rechts/Rechts-Kettengewirke gemäß Einzelheit in Fig. 2.

An embodiment of the invention is shown in the drawing and will be described in more detail below. Show it:

Fig. 1

the schematic representation of the knitting point of a right / right warp knitting machine for performing the method according to the invention,

Fig. 2

2 shows a section through a right / right warp knitted fabric according to FIG. 1,

Fig. 3

the schematic representation of a plan view of the right / right warp knitted according to the detail in Fig. 2nd

Ways of Carrying Out the Invention

According to the section shown in Fig. 1, the knitting point of a right-right warp knitting machine from a front and rear needle bar 1, 1 'with knitting needles and the associated tapping edges 2, 2 'and the thread laying members are formed. These consist of at least one oscillating base rail 3, which Laying for stitch formation 3 ', 3 "on the front and rear needle bar 1, 1' realized, and assigned to at least one of the front and rear needle bar 1,1 ' vibrating weft guide 4, 5, via the additional 0 ° weft threads (4 ', 5'), which can be moved laterally if necessary. The thread laying organs also consist of non-vibrating thread layers 6 to 13. The thread layer 6 is assigned to the front needle bar 1 and carries a 90 ° thread system 6 'which of the basic threads 3 'are tied in the area of the front needle bar 1 by means of a laying rail 3 becomes. Depending on the line of force, the thread layer 6 can also suspend or just lay over sections. The thread layers 7 and 9 are for the entry of Diagonal threads 7 ', 9' are provided, which are designed, for example, as tubes and on an oscillating or rotating driving device at a distance from the needle pitch are arranged over the entire working width. After reaching the the respective fabric edge, the thread layers 7 move into the position of the thread layers 9 and the thread layer 9 in the position of the thread layer 7. The offset length per stitch row depends on the desired laying angle of the diagonal threads 7 ', 9'. If necessary, the diagonal threads 7 ', 9' can also be suspended according to the pattern and as 0 ° threads run.

The rigidly arranged thread layer 8 is provided for feeding the 0 ° threads 8 ', which lie in the knitted fabric between the diagonal threads 7 'and 9'. The thread layer 10 to 13 are assigned to the rear needle bar 1 '. The rear diagonal threads 10 ' and 12 'are laid through the thread layers 10 and 12, the entry principle that of the thread layer 7 and 9 corresponds.

The rear 0 ° threads 11 'are analogous to those by rigidly arranged thread layers 11 Threads 8 'placed between the diagonal threads 10' and 12 '. The thread layer 13 carries this rear 90 ° thread system 13 ', whereby, as with thread layer 6, also an interruption or an entry can be made over partial routes.

According to FIG. 2, the method according to the invention results in the following arrangement the thread layers in the knitted fabric: 90 °; -diagonal; 0 °; + Diagonal; 0 ° with sample offset; 0 ° with pattern-based offset; -diagonal; 0 °; + Diagonal; 90 °. The laying angles of the diagonal threads 7 'and 9' or 10 'and 12' are by extension or Shortening of the underlay length can be changed per row of stitches.

In Figure 3 is a crossing point of four thread systems 6 ', 7', 8 'and 9' at the front needle bar 1 shown. Accordingly, the 90 ° threads 6 'are in front of the Diagonal threads 7 'and 9' and the 0 ° threads 8 'run between the digital threads 7', 9 '.

The 90 ° threads, diagonal threads and 0 ° threads on the rear needle bar are analogous 1 'with the thread systems 10', 11 ', 12' and 13 'arranged, corresponding to the Right / right knitted structure the crossing points of the front thread systems and the rear thread systems are arranged offset to one another.

With the method according to the invention, multiaxial structures with one targeted line of force in all directions for a variety of applications optimally manufacture.

Claims (6)

1. Method for the production of multiaxial warp knit fabrics with extended threads in the longitudinal, transverse and diagonal directions as a result of the direct insertion of the diagonal threads as weft sections onto the backs of the rising needles of the needle bars (1; 1'), characterized in that at least two diagonal thread systems (7', 9'; 10', 12') are simultaneously inserted contrarily as part wefts for each needle bar (1; 1') on a right/right warp knitting machine.
2. Method according to claim 1, characterized in that 0° threads (8', 11') are inserted as upright wefts between the diagonal thread systems (7', 9'; 10', 12').
3. Method according to claims 1 and 2, characterized in that 90° threads (6'; 13') are simultaneously inserted as through wefts in line with the stitch rows.
4. Method according to claim 3, characterized in that the 90° threads (6'; 13') are partially discontinued or continue to operate as a part weft.
5. Method according to claims 1 to 4, characterized in that, in addition, 0° threads (4', 5') run in, which are racked laterally at a distance from one another.
6. Method according to claims 1 to 5, characterized in that the diagonal threads (7', 9'; 10', 12') are discontinued according to the pattern and run as 0° threads.

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