GB2078795A - Combined knitting and weaving process for fabric forming - Google Patents

Abstract

To form a fringed selvedge a needle 18 is lowered to catch the weft thread loop inserted by a needle 31. The loop needle 18 is actuated by a cam 27 and a shaft 12 having a give way device 13, 16 so that lowering of the needle 18 to catch a loop may be overridden by a cam driven device 24. The needle is adjustably positioned for different length loops and there may be more than one needle. <IMAGE>

Description

SPECIFICATION Combined knitting and weaving process for fabric forming This invention relates to fabric forming and is particularly concerned with a combined weaving and knitting process for the production of decorative fabric edge trimming, especially looped trimming formed by loops of thread or yarn appendant to, but integral with, the fabric body and such as might generally be categorised as braids, fringes and ruches. The invention is particularly, but not exclusively, concerned with a looped edge braid or fringe for curtain or upholstery trimming, but a wider range of applications, such as for dresses and lampshades is appropriate.

In the conventional methods for producing fringed braid, a conventional weaving process, such as Leno weaving, might be employed and in which the shaping of the fringe, in particular the varying fringe width and the trailing fringe loops or strands themselves are formed by varying the inter-weaving of warp and weft threads. Leno weaving may be carried out in principle upon any form of weaving machine, and indeed on the needle loom, which is a faster type of loom, as compared with, say, a shuttle type loom, Leno weaving has hitherto been the only means of producing fringed braid. However, even this process is difficult and expensive and it has normally been preferred to use a simpler, but quite different, knitting, rather than weaving, process which is nevertheless limited in running speed and thus production efficiency.

Weaving may generally be regarded as the formation of fabric by interlacing strands of yarn or thread, commonly in a regular grid or matrix fashion by arranging a parallel series of warp threads and interweaving a weft thread transversely thereto. In contrast knitting may generally be regarded as the interlacing of strands in a series of connected loops.

The present invention represents a modification of a conventional weaving machine and process, and in particular of a needle type loom by which the elements of weaving and knitting may be regarded as combined. For the purpose of illustration only, and in no way limiting the scope of the invention claimed, the process according to the invention might be regarded as characterised by a majority element of weaving, for example to the extent of 70% of the process, together with a minority element of knitting, for example to the extent of 30% of the process.

According to one aspect of the invention, a thread interaction process combining the elements of weaving and knitting for fabric formation, comprises the steps of forming an array of warp threads and selectively interweaving said array of warp threads with one or more weft threads to form the fabric body, the successive passage of a weft thread through the selectively displaced array of warp threads being selectively interruptable at a point spaced from the run of warp threads, to catch a loop for a weft thread before return to the body of the warp threads, whereby the loop is external to the main body of the woven fabric and is held in position by the interweaving of the body of the warp and weft threads.

According to another aspect of the present invention there is provided apparatus comprising a weaving machine or loom adapted to perform the foregoing method. In particular, in apparatus according to the invention a catcher or picker arm such as that which might be employed in a knitting machine is incorporated into a weaving machine, desirably a needle loom, for the purpose of loop formation.

The spacing of the weft thread catcher arm from the body of the fabric may be varied in order to vary the lateral extent of the loop and indeed the relative widths of the loop and fabric body may be varied.

In a preferred construction, a pivoted catcher arm is driven by a cam shaft incorporated in a weaving machine or loom and driven in synchronism with the primary operation of the loom. Such a cam shaft may, for example, be incorporated in the loom for the purpose of periodically compacting the width of the fabric after one or more transverse passes of the weft thread, in order to maintain a consistent desired width.

There now follows a description of a particular embodiment of the invention, by way of example only, with reference to the accompanying diagrammatic drawings, in which: Figure 1 shows a schematic layout of an adaption or modification to a weaving machine or loom to provide a knitting facility for fabric formation according to the present invention; Figure 2 shows a general side elevation of the weaving machine incorporating the modification shown in Figure 1; and Figure 3 shows a plan view of the machine shown in Figure 2.

Referring to the drawings, a weaving machine or loom, specifically of the general character of a needle loom, is adapted or modified according to the present invention by the provision of an additional weft thread catcher or picker arm arrangement as shown in more detail in Figure 1.

The basic needle loom 50, as shown in Figures 2 and 3, comprises a generally conventional mechanism for forming a parallel run of warp threads 41 from supply spools 47, with a mechanism 42 for selectively displacing one or more warp threads relative to the other warp threads. The width of fabric 37 produced may be varied according to the number of warp threads employed.

The tensioning spacing feeding and withdrawal of thread and fabric may be effected in the conventional manner well known to persons skilled in the art and will not be described further.

A weft thread 32 is carried from a supply spool 45 in a loop or eye of a swinging needle mounted on a swinging needle arm assembly 43 installed at one side of the machine and arranged to enable the weft thread 32 to be passed freely from one side of the array of warp threads 41 to the other.

This is possible because the warp threads 41 are separated into two general planes 38, 39 eventually brought together in the woven fabric 37, the actual threads present at each plane being determined by the selective displacement of weft threads mechanism 42. An additional catcher thread may be employed at one side of the warp threads to form a continuous return edge or selvage for the interlaced weft thread 32.

The primary drive mechanism 48 for the various machine functions is housed in the base of the machine.

In Figure 1 the relative dispositions of the loom modification and the remainder of the conventional loom are depicted schematically; in particular the modification is shown on a larger scale than the inset of the warp/weft thread fabric run. Thus, referring to Figure 1, a form of hinged or pivoted weft thread loop catcher arm or picker bar 22, carrying a picker needle 1 8 in a slidably adjustable support block 17, is mounted at one side of the loom for movement (indicated by arrow 30) in a generally vertical plane intersecting the generally horizontal plane of movement (indicated by arrow 36) of a swinging needle arm 31. The arm 22 is fitted into a collar 14 fitted around a pivot shaft 12 supported at opposite ends by bearing blocks 11.The collar 14 and thus the arm 22 are drivably engagable with the pivot shaft 12 by means of a drive collar arrangement with opposed collars 13 and 16 and an intervening torsional biasing spring 1 5. The drive arrangement enables the arm 22 to be moved about the pivot shaft 12 independently of a primary drive (described below) and thus the movement of the arm 22 under the primary drive can be over-ridden or disengaged by selectively raising the arm 22 by means of a lifting bar assembly 24, itself driven by means of a rotating cam and biased follower arm 25, synchronised with the primary drive for the arm 22.

Provision is made for the installation of one or more additional catcher arms or picker bars 22, all of which can be driven by one and the same primary drive, comprising a crank mechanism 29 and selectively over-ridden by the cam drive 25.

Over-riding control of the movement of each arm 22 is achieved by means of an adjustably mounted pick-up limb 20 on the over-ride assembly 24. The latter comprises a series of parallel bars which can support one or more pick-up limbs 20, adjustably positioned by means of locking screws 1 9.

The picker bar or catcher arm assembly 40 is generally to one side of the loom as shown more clearly in the general assembly or layout drawings of Figures 2 and 3.

The primary drive 29 incorporates a rotatable cam 28 with a cam groove or pattern chain path 27 on one face thereof, and on which is located the end of a crank follower arm 26, drivably connected to the pivot shaft 12. Thus, as the cam 28 rotates, the crank 26 follows an upward and downward movement along the path 27.The latter makes an inward turn at one point on the circumference of the cam 28, at which position the interlocated crank follower 26 is in the fully lowered position and thus so is the catcher arm 22 and the associated picker needle 1 8. Conversely, with the crank follower 26 in generally the opposite position to the indent in the path 27, the catcher arm 22 is in the fully elevated position and is in fact clear of the needle arm 31 carrying the weft thread 32, which can thereby return through the selectively separated warp threads 38, 39 and- be interlaced tightly into the main body of the fabric 37.

With the picker needle 1 8 lowered, the loop 33 of the weft thread 32 is caught just upon its return motion and is prevented from being pulled back into the body of the fabric 37, but is rather lefts a transverse lateral loop tied into the main body of the fabric 37 by the continuation of the weft thread 32 as it is returned through the selectively displaced warp threads 38, 39.

The weft feeding mechanism 45 is arranged to maintain the tension of the weft thread during the sudden paying out of a weft thread loop 33.

The tension in the weft thread 32 is maintained as the loop is formed and until the weft thread is locked into the body of the fabric.

It will be appreciated that by varying the position of the catcher or picker needle 1 8, so the transverse extent and position of the weft loop 33 can be varied. Thus movement of the arm 22 along the shaft 12 varies the transverse extent of the loop and movement of the picker needle 1 8 along the arm 22 determines the longitudinal position of the fabric body or with respect to the array of warp threads 41, at which the weft edge loop 33 is formed.

As the fabric 37 is formed, it is wound onto a takeup mechanism, allowing the same picker needle 18 to form further weft edge loops spaced longitudinally along the fabric 37 at regular intervals determined by the synchronised cam drives 25 and 29.

The successive interlacing or weaving action of the weft thread 32 as it is carried back into the fabric 37 after formation of a weft edge loop 33 serves to tie the loop 33 securely into the body of the fabric 37 and unravelling of the fabric body 37 as a whole is prevented by the interlacing of the weft thread 32 with a longitudinal locking or catch thread at the opposite side to the looping station just described.

Additional strands or tassels may be attached to individual loops or the loops may be split to form individual strands or tassels.

It will be appreciated that one loop picker can be used to produce a varying looped edge, achieving a scalloped effect. Indeed, as many as twelve or more pickers may be used on a machine of appropriate width, but five to six pickers might prove a practical limit for most purposes.

Control of all the picker bars or catcher arms is by means of a combined adjustable throat assembly 24 as described.

The combined weaving and knitting method according to the invention and the apparatus for performing the method enables the production of decorative fringes for some considerably less (even half) the normal cost by conventional means, such as special purpose crochet or knitting machines. Thus, a conventional knitting machine running at ten courses per minute, representing a maximum 250 picks per minute or a minimum of 50 picks per minute - say an average of 90 to 100 picks per minute, as compared with the 1 ,000 to 1,500 picks per minute achievable with a needle loom adapted according to the present invention.

Apparatus according to the present invention effectively employs an automatically controlled loop forming arm which casts off the loop when the loop is formed. Several loops, for example four, may be formed in succession then the loop forming arm would be lifted, followed by a series of weaving operations to bind the loops of the fabric body.

The loop and thus fringe width could vary between say half an inch and twenty-four inch for a conventional needle loom, as can the relative widths of fabric body and loops.

The invention as applied in the particular embodiment described has the advantages of use of existing cam drive machinery, for example that typically employed to control fabric width feature particularly used for delicate fabrics - and uses the standard warp and weft thread feed mechanisms.

Claims (7)

1. A thread interaction apparatus for the production of woven fabric with appendant loops, the apparatus comprising means for forming an array of selectively interspaced warp threads and for selectively interweaving a weft thread therethrough, with catcher means for catching the weft thread during its return path to form a loop and over-ride means for over-riding the loop formation.

2. Apparatus as claimed in Claim 1 with automatic control means for synchronising the formation of weft thread edge loops of desired width and spacing with the selective interweaving of warp and weft threads to form the fabric body.

3. Apparatus as claimed in Claim 1 or Claim 2, and substantially as hereinbefore described with reference to, and as shown in, Figures 1,2 and 3 of the accompanying drawings.

4. A method of forming looped edge fabric comprising the steps of weaving on a needle loom and interrupting the weaving process by a knitting action, in which a weft thread on its return is caught and held by a selective displacement mechanism and the weft thread continued to be interlaced into the body of the fabric.

5. A method of forming looped edge fabric substantially as hereinbefore described with reference to the accompanying drawings.

6. Fabric produced by apparatus as claimed in any of Claims 1 to 3.

7. Fabric produced by the method as claimed in Claim 4 or Claim 5.