US3606770A

US3606770A - Seamless tubular net and method of making the same

Info

Publication number: US3606770A
Application number: US784835A
Authority: US
Inventors: Karl Kohl
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-12-20
Filing date: 1968-12-18
Publication date: 1971-09-21
Anticipated expiration: 1988-09-21
Also published as: GB1183890A

Abstract

A SEAMLESS TUBULAR NET IS MADE ON A WRAP KNITTING MACHINE HAVING TWO NEEDLE BEDS AND THREE GUIDE BARS, THE YARNS OF TWO BARS KNITTING WARP CHAINS, AND THE THIRD GUIDE BAR LAYING-IN A YARN TO CONNECT THE CHAINS IN TWO LAYERS. THE LAID-IN YARN IS SHIFTED STEPWISE IN A WALEWISE DIRECTION SO THAT IT FORMS A HELIX IN THE FINISHED NET. THE CIRCUMFERENTIALLY CONSECUTIVE PORTIONS OF THE LAID-IN YARN CONNECT CHAIN STITCHES IN THE SAME COURSE SO THAT THE SEVERAL TURNS OF THE HELIX ARE BOUND TO STITCHES IN THE SAME CHAIN WHICH ARE SEPARATED BY STITCHES FREE FROM LAID-IN YARN.

Description

sept. 21.1971 3,606,710

'NSEAMLESS TUBULAR NET AND METHOD OF MAKING THE SAME A K. Kom.`

Filed Dec. 18, 1968 United States Patent O1 hee 3,606,770 SEAMLESS TUBULAR NET AND METHOD OF MAKING THE SAME Karl Kohl, Offenbacher Landstr. 20, Hanstadt am Main, Germany Filed Dec. 1s, 196s, ser. No. 784,835 Claims priority, application Germany, Dec. 20, 1967, P 16 35 875.1 Int. Cl. D04b 23/02 U.S. Cl. 66-87 2 Claims ABSTRACT OF THE DISCLOSURE A seamless tubular net is made on a wrap knitting machine having two needle beds and three guide bars, the yarns of two bars knitting warp chains, and the third guide bar laying-in a yarn to connect the chains in two layers. The laid-in yarn is shifted stepwise in a walewise direction so that it forms a helix in the nished net. The circumferentially consecutive portions of the laid-in yarn connect chain stitches in the same course so that the several turns of the helix are bound to stitches in the same chain which are separated by stitches free from laid-in yarn.

BACKGROUND OF THE INVENTION This invention relates to seamless tubular nets knitted on a warp-knitting machine having two needle beds, and to a method of operating the machine so as to produce the net.

It is known to produce tubular nets by connectin-g the several chains knitted on two needle beds by means of laid-in yarns which connect two or three adjacent chaims. The fabric so produced may constitute a seamless net, but its chains are thick relative to the yarn employed for preparing them. If it is desired to use elastic laying-in yarn, the expenditure for the elastic yarn is so high as to make the seamless tube economically unattractive for many applications for which it would otherwise be emiently suitable.

A primary object of the invention is the provision of a warp-knitted, seamless, tubular net in which the amount of elastic yarn employed can be reduced to the minimum required for adequate mechanical strength, and is minimal if little strength is needed.

SUMMARY OF THE INVENTION In the net of the invention, circumferentially consecutive portions of one laid-in yarn are bound in respective spaced chains to stitches aligned in a circumferential or coursewise direction, but the consecutve portions of the laid-in yarn are offset in the same walewise direction, which is axial relatve to the tube into which the fabric may be expanded. The laid-in yarn thus extends about the axis of the expanded tubular net in an approximate helix.

The several turns of the helix are bound in each chain to stitches of the chain which are separated from each other by at least two chain stitches free from the laid-in yarn. The walewise offset of the laid-in yarn portions is provided by linking portions of the yarn which extend axially in the chain which extends between the two coursewise consecutive portions of the laid-in yarn.

' For a tubular net having a given number of Warp chains, the amount of laid-in yarn employed may be varied to suit requirements of mechanical strength or mesh size by varying the number of gaps between adjacent chains that are spanned by the laid-in yarn in the same course. A minimum of laid-in yarn is used for a given length of tubular net, if the laid-in yarn spans only one such gap before shifting to the next course, but

3,606,770 Patented Sept. 21, 1971 two or more gaps may be spanned by the laid-in yarn in the same course to provide a desired small mesh size 0r higher circumferential strength. The length of each coursewise portion of the laid-in yarn is preferably, though not necessarily, equal. A single laid-in yarn is adequate under most conditions.

Several methods for making the above-described tubular net will readily suggest themselves to those skilled in the art. In a method which has been found particularly advantageous, the needles in each of the front and rear beds are spaced apart and respectively knit two layers of spaced warp chains which are connected into a tube by the laid-in yarn in a manner basically known in itself. The tube is expanded by pulling the marginally connected layers apart.

Two guide bars are threaded with the yarns for the warp chains in the two layers, and a third guide bar is threaded with the laying yarn. The pattern wheel or chain which causes the Shogging motion of the third guide bar is selected in such a manner that sequential portions of the laying-in yarn are offset in a common walsewise direction, each portion being laid coursewise between a plurality of respective stitches of the chains which are aligned in a coursewise direction, and being bound to the associated aligned stitches.

The lapping movements of the third yarn guide are such that the laying-in yarn is looped about the needles of the front bed while moving from the left to the right along all active needles of the needle beds, while being prevented from making loops about the needles of the rear bed, the opposite procedure being observed during novement of the third guide bar from the right to the eft.

Other features, additional objects and many of the attendant advantages of this invention will readily be appreciated as the same becomes better understood from the following description when considered in connection with the appended drawing.

of the third yarn guide in making the fabrics of FIGS. 2a and 2b.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawing in detail, and initially to FIG. l, there is seen a tubular seamless net of the invention in the expanded condition. The net consists of nine chains of warp stitches widely separated from each other in a circumferential or coursewise direction, and held together by a single, laid-in, elastic yarn 2 in the manner shown in FIG. la. On the relatively small scale of FIG. l, the laid-in yarn 2 appears to form a continuous helix about the axis of the net, its several turns being spaced widely in an axial or walewise direction so that a substantial number of chain stitches between successive turns is free from the laid-in yarn in each chain.

Details of the disposition of the laid-in yarn in respective tubular nets of the invention are better seen in FIGS. 2a, 2b, and 2c which show nets closely similar to that of FIG. 1 in diagrammatic, developed views. 'I'he nine

Warp chains

1a, 1b, 1c, etc. are knitted on a machine having two needle beds in which the needles are spaced from each other by means of two correspondingly threaded guide bars n a known manner to form two layers of chains which may be separated in the middle while being connected at the edges by means of laid-in yarn.

As is shown in FIG. 2a, the laying-in yarn connects the chains 1a, 1b in the course 3a being bound to the respective stitches of the two chains. The yarn then progresses walewise in the chain 1b by one course spacing into the course 3b in which it similarly connects the

chains

1b and 1c. This procedure is repeated until the laid-in yarn reverts to the chain 1a in a course offset walewise by nine stitches from the course 3a.

In the `fabric indicated in FIG. 2b, the laid-in yarn 2 extends over the two gaps between the

chains

1a, 1b, 1c in the same course, then shifts to the course 3b for bridging the next two gaps, and reverts to the chain '1a in the fth course. Each coursewise portion of the laid-in yarn is bound to the three stitches of the connected chains a which are aligned in a coursewise direction.

Yet another arrangement is illustrated in FIG. 2c in which the laid-in yarn 2 spans four gaps in the course 3a to connect ve chains before switching to the course 3b in which it again bridges four gaps. The approximate helix formed by the laid-in yarn 2 in the fabric illustrated in FIG. 2c has one half the pitch of the helix in FIG. 2b and one quarter the pitch of the helix in FIG. 2a. While the number of chains connected by the same coursewise run of the laid-in fabric is the same in each of FIGS. 2a, 2b, 2c, and each step of the helix is one course high, the pattern chain or pattern wheel controlling the shogging motion of the third or laying-in yarn guide may be chosen to provide steps of varying length and height in the same approximate helix.

The lapping movements of the third or laying-in guide bar in knitting the fabrics of FIGS. 2a and 2b, respectively, will be evident from the point diagrams of FIGS. 3a and 3b, respectively. The movements of the other two guide bars which knit plain chains of warp stitches on the same needles in an obvious manner have not been shown.

The laying-in guide bar makes a fall plate loop over the needles of the front bed F while moving along the needle beds in one longitudinal direction, but does not perform lapping movements relative to the needles of the rear bed R which are longitudinally interposed between the active needles for the front bed. This movement of the third guide bar is indicated by a solid line in each of FIGS. 3a and 3b. The return movement of the third guide bar is controlled in such a manner that fall plate loops are made on the active knitting needles of the rear bed R, while no lapping movements are performed relative to the front bed needles. This is shown in broken lines in FIGS. 3a and 3b. FIGS. 3a and 3b respectively correspond to the fabrics of FIGS. 2a and 2b.

A fabric of the invention consisting of six chains of warp stitches and a single laid-in yarn arranged in a helix of steeppitch, that is, a walewise offset by one course in each chain, may be produced by repeating shogging motions of three guide bars in the following pattern, the middle bar being threaded with the sole laying-in yarn:

Front guide bar: 2-0/0-0/0-2/0-0/ Middle bar O-O/2-2/2Z/4-4/4-4/6-6/4-4/4-4/2-2/ 2-2/ Rear guide bar: O O/OLZ/O-O/Z-O/ The distance between successive turns of the helix as measured along each chain is tive stitches in the tubular net so produced.

The most important advantages of this invention are achieved if the fabric essentially consists of the several chains of warp stitches and a single laid-in yarn. If a net of greater strength or of smaller mesh size is desired, more than one laid-in yarn may be used to form a double helix in an obvious manner. Many tubular nets of the invention may be produced side by side on the same pair of needle beds by means of three suitably threaded guide bars as will be obvious to those skilled in the art, the above decription being limited to the manner of producing one ofthe several nets which simultaneously come from the knitting machine in continuous strands and may be cut to a desired length or otherwise yprocessed in a manner not directly relevant to this invention.

What is claimed is:

1. A method of operating a warp knitting machine having three guide bars and two needle beds, yarn guides and knitting needles on said guide bars and said needle beds respectively, and actuating means for operating said guide bars and said knitting needles, only one of said guide bars being threaded with a laying-in yarn, the actuating means beig operative for knitting two layers of warp chains on said needle beds respectively, and for connecting said warp chains into a tubular fabric by portions of said layingyarn extending coursewise between said chains, the improvement which comprises:

(a) offsetting sequential portions of said laying-in yarn in a common walewise direction,

( l) each of said portions being laid coursewise between a plurality of respective stitches of said chains aligned in a coursewise direction, and bound with said aligned stitches.

2. A method as set forth in claim 1, wherein said one guide bar makes lapping movements for looping said laying-in yarn about the needles of one of said beds, while the laying-in yarn is prevented from making loops about the needles of the other bed, while said one guide bar moves coursewise along said needle beds in one direction, said one guide bar making lapping movements for looping said laying-in yarn about the needles of the other needle bed while said laying-in yarn is prevented from making loops about the needles of said one needle bed while said one guide bar moves in a coursewise direction opposite to said one direction.

References Cited UNITED STATES PATENTS Re. 26,496 12./1968 Krauss 66-193 459,866 9/1891 Clewley 66-170 3,178,910 4/1965 Hammerle 66-190X 3,251,201 5/1966 Newman 66--192 3,513,668 5/1970 Mintz 66-193 RONALD FELDBAUM, Primary Examiner