Warp knitted ware with reinforcing threads

A warp knitted fabric employs a warp knitted pattern as the ground stitches. In this novel fabric there are reinforcing threads of a substantially rigid material. The weft threads may run parallel to each other and are located between the needle loops of stitch rows that follow each other sequentially in the warping direction. Additionally, there are two sets of diagonal threads both of which run alternatively: (a) between two needle loops of neighboring wales and (b) between two needle loops of successive stitch rows. Laid-in warp threads may be provided between needle loops of adjacent wales. There is thus provided a fabric having higher rigidity in all directions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to warp knitted ware utilizing tricot, chain 
or other stitches to form the ground fabric of the ware into which are 
laid reinforcing threads such as weft threads and various filler threads 
which are located in the vicinity of needle loops of adjacent chain 
stitches. 
2. Discussion of the Relevant Art 
As reinforcing threads, it is particularly desirable to utilize glass or 
carbon fibers which provide a substantial rigidity in the direction of 
thread extension. Such threads are somewhat inflexible and must therefore 
be utilized in a substantially linear fashion, that is to say they cannot 
be woven together as warps or wefts. These products are usually coated 
with a synthetic material so that they can be utilized as planes or as 
laminates for the formation of synthetic shaped bodies of high rigidity. 
In a known type of warp knitted goods of the prior art [see Textiltechnik 
31 (1981) p. 493] only chains and lightly crossing weft threads are 
utilized. This arrangement gives rise to an increased rigidity in the warp 
direction and in the weft direction but not in the diagonal direction. It 
should further be noted that the weft threads are partially penetrated by 
the needles of the needle bed which negatively affects the stability of 
the material. 
It has further been disclosed (U.S. Pat. No. 3,819,461) that rigid threads 
may be used solely in the weft direction and be held together by chain 
stitches. This gives rise to higher stability in the weft direction than 
where the weft threads cross each other. In all other directions, however, 
the rigidity is not satisfactory. 
It is further known (U.S. Pat. No. 2,890,579) to overlay a non-woven fabric 
with diagonal threads or warp inserts and to hold everything together by 
stitch sewing. In this material also, it should be noted that the crossing 
threads are penetrated by the needles of the needle bed which also 
negatively affects their strength. 
Accordingly, there is a need for a warp knitted material which has equal 
rigidity in all directions in order to provide the highest total rigidity 
possible. 
SUMMARY OF THE INVENTION 
A fabric according to the principles of the present invention is enmeshed 
by stitched ground ware. The fabric has a plurality of parallel inlaid 
weft threads and a plurality of wales of warp thread stitched by rows. 
Each of the plurality of parallel inlaid weft threads are laidin across 
the wales and between two adjacent rows of stitch loops in the warp 
thread. The fabric also has a first and second plurality of diagonally 
inlaid threads. The first plurality crosses the second plurality. Each of 
the inlaid threads of the first and second plurality run alternatively and 
repetitively: (a) between two stitch loops of a corresponding adjacent 
pair of said wales and (b) between two stitch loops of two successive rows 
of stitch loops of the warp threads. 
According to a related method of the same invention, fabric is formed from 
warp, weft and diagonal threads. The method includes the step of laying-in 
weft threads in a given series of transverse rows. Another step is 
laying-in diagonal thread in a first series of diagonal rows, each 
crossing the weft threads at an acute angle. The method also includes the 
step of laying-in diagonal thread in a second series of diagonal rows, 
each crossing the weft threads at an acute angle. The diagonal thread of 
the second series crosses that of the first series. Another step of the 
method is stitching the warp thread about the weft and diagonal threads to 
form a ground ware. 
In one embodiment of the invention, the diagonal threads are provided 
between the planes of the weft inserted threads and the inlaid warp 
threads. This mode of operation makes it possible to provide both the weft 
threads and the diagonal threads on top of each other in a single weft 
thread magazine and to thus provide them to the needle bed. 
In another embodiment the inlaid warp threads are provided between the 
diagonal threads and the weft threads. This has the advantage of providing 
goods having a lower longitudinally ribbed appearance upon which the 
coating material may be more readily laid.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The fabric of FIG. 1 is illustrated with four types of reinforcing threads 
of a substantially rigid material. Suitable fibers for this purpose are 
those of glass, carbon, high density polyester or combinations of the 
above (for example dtex 500 or higher values). These reinforcing threads 
comprise weft threads 1, a first plurality of diagonally inlaid threads 2, 
a second plurality of diagonally inlaid threads 3, and longitudinal (warp) 
inlaid threads 4. These reinforcing threads are bound into a knitted 
fabric 5, by means of one or more substantially thinner warp threads 6 
(for example, dtex 76). 
The warping system forms stitches 7 with needle loops 8. There are thus 
formed running wales 9 in the warp dirction and stitch rows A, B, C, D, 
etc. in the weft direction. 
The weft threads 1 run parallel to each other and are located between the 
needle loops 8 of adjacent machine rows A, B, C, D, etc. Also the diagonal 
threads 2 and 3 lie mutually parallel within their respective series and 
they run in alternating fashion between two needle loops 8 of neighboring 
wales 9 and between two needle loops 8 in sequentially following stitch 
row A, B, C and D in the warp direction. The inlaid threads 4 are 
similarly provided in a mutually parallel manner and are located between 
the needle loops 8 of neighboring wales 9. In this manner, the needles of 
the needle beds can always pass through the interstices of the reinforcing 
threads. The inlaid weft thread 1 and the diagonal threads 2 and 3 are 
provided in a conventional manner, for example, by means of known magazine 
arrangement for weft threads and diagonal threads. 
For example, the weft thread magazine of the knitting machine of U.S. Pat. 
No. 4,395,888 can lay-in threads in a weft or diagonal direction. 
Moreover, inserts are provided from a warp beam in the conventional 
manner. See for example, D. F. Palieng, Warp Kniitting Technology, 
Columbine Press, Buxton, Derbyshire, U.K. (1970). Such knitting equipment 
operates to lay-in warp thread 4 through ordinary thread guides. 
Thus, thread magazines as shown in U.S. Pat. No. 4,395,888 place the 
reinforcing threads on carrying chains in the weft direction in addition 
to the diagonal direction. These reinforcing threads are oriented and 
their delivery to the needle bed (see above patent) timed in such a manner 
that they are not penetrated by the needles of the needle bed. This is 
possible because these reinforcing threads are provided in a manner 
directly dependent upon the stitch formation cycle of the above knitting 
machine. The above machine is so configured to provide the reinforcing 
threads in parallel rows. In the optimal embodiment the inlaid warp and 
weft threads subtend an angle of 90 degrees to each other and the diagonal 
threads subtend an angle of 45 degrees to both the weft and the warp 
inserted threads 1, 4. Such an orientation provides the highest possible 
rigidity in the longitudinal, transverse and diagonal directions of the 
ware. Since the needles (not shown) can always run between the individual 
reinforcing threads, the knitting cycle may proceed very readily. The 
ground fabric of the goods can thus be made of very thin warp threads 
which are sufficient to hold the reinforcing threads together until a 
subsequent coating stage in their ultimate use. 
Thus, there are provided a plurality of weft threads 1 running parallel to 
each other and which are located between the needle loops 8 of stitch rows 
A, B, C, D running in the warping direction, and additionally comprising 
two sets of diagonal threads 2, 3 which run alternately between two needle 
loops 8 in successive stitch rows A, B, C, D in the warping direction. 
In the embodiment of FIGS. 3 and 4 the corresponding parts are illustrated 
by part numbers incremented by ten. This particular embodiment may be 
differentiated from that of FIGS. 1 and 2 in that the stitch pattern is 
not tricot but rather chain stitch. Furthermore, it will be noted that the 
warp inserts 14 are located between the weft threads 11 and the diagonal 
threads 12 and 13. 
The ground ware is thus constructed in a very simple manner, and may 
comprise solely chain stitches. Such chain stitches contribute to the 
longitudinal stability with a minimum thread consumption for each stitch 
row. However, other stitches such as the 2-0-4-6 stitch, the Atlas stitch 
or the Koeper (two needle overlap) stitch are equally utilizable. 
It will be clear to those skilled in the art that other combinations of 
orientation of the reinforcing threads in relationship to each other are 
possible and are to be considered as included within the scope of the 
present invention. 
The terms "weft", "diagonal" and "warp" threads include not only single 
filaments but also groups of single filaments or thread combinations which 
run between the needle loops in the above described manner. 
If advantagous in the ultimate use of the material thus produced, it is 
also considered to be in the scope of the present invention to omit 
certain of the reinforcing threads; for example, to insert only every 
second possible weft thread; and/or diagonal thread; and/or inlaid warp 
thread. Also, if the ultimate material is intended to have a ribbed 
appearance, certain of the warp insert threads may be omitted. 
It will be understood that various other changes in the details, materials, 
arrangement of parts and operating conditions which have been herein 
described and illustrated in order to explain the nature of the invention 
may be made by those skilled in the art within the principles and scope of 
instant invention.