GB2128208A - Method of and apparatus for forming knitted fabric - Google Patents

Abstract

In a method of and apparatus for forming a knitted fabric without knitting needles, new loops are formed in succession by blowing required loop lengths of a yarn (13) with air through nozzles (8) into primary loops in the preceding course. The yarn-feeding nozzles (8) blow the loop lengths through the primary loops (22) and holes (3A) e.g. in a rotating cylinder 2, ejector air nozzles (9) blow the new loops back through the holes when the course has been lowered sufficiently as by rollers 19, and loop-raising nozzles raise the new loops and align them around the small holes (3). An embodiment for forming rib fabric has inner and outer rotating rings with respective rings of holes and the nozzles for inserting the yarn oscillate between the rings. <IMAGE>

Description

SPECIFICATION PJlethod of and apparatus for forming knitted fabric This invention relates to methods of and apparatus forforminga knittedfabricwithouttheuseofknitting needles.

As is widely known, the knitted fabric generally called hosiery is formed by the reciprocating move mentofamultiplicityofknitting needles disposed in predetermined positions on a knitting machine. The reciprocating movements of the knitting needles are controlled by cams in most knitting machines. Accordingly, in a method of knitting depending on conventional knitting needles, any remarkable increase in productivity is very unlikely because of various limiting factors, such as wear of the knitting needles, the operating speed ofthe needles, the cam mechanism, and the high-level technology required forthe operation and maintenance of the machines due to their complicated structure.

In accordance with the present invention there is provided a method of forming a knitted fabric in which new loops are formed in succession by blowing required loop lengths of continuous yarn together with air through nozzles into primary loops in the preceding course.

Also in accordance with the invention there is provided apparatus for forming a knitted fabric comprising a cylinder having a multiplicity of small holes which are provided in a row around the circumference of the cylinder at intervals each equal to the distance between wales of the fabric to be knitted, meansfor rotating the cylinder, yarn4eeding air nozzles having tips directed towards the holes, ejector air nozzles directed towards the holes and arranged in positions radially inwardly ofthe yarn feeding positions and in the direction towards which the cylinder rotates, said yarn-feeding nozzles and ejector air nozzles jetting air intermittently, and yarn-feeding means forsupplying yarn to the yarn4eeding nozzles intermittently in lengths corresponding to the loops to be formed.

The invention also includes apparatusforforming a knitted fabric comprising a cylinder having a multiplic ityofsmall holes which are provided in a Crow around the circumference of the cylinder at intervals each equal to the distance between wales of the fabric to be knitted, means for rotating the cylinder, yarn-feediing air nozzles having tips directed towards the holes, ejector air nozzles directed towards the holes and arrangedl in posiltions radially inwarcily of the yarn feeding positions and in the direction towards which the cylinder rotates, said yarn-feeding nozzles and ejectorairnozzlesjetting airintermittently,yarn- feeding means for supplying yarn to the yarn-feeding nozzles continuously, and an auxiliary nozzle for emitting airadjacentto each yarn-feeding nozzleata distance therefrom equal to one half of the distance between wales.

Using the present invention, productivity is strikingly improved, the cost of maintenance and management is reduced because there is no necessity to provide needle grooves and cams and to replace knitting needles, thus also enabling production costs to be cut. Moreover, because there is almost no friction exerted on the yarn during knitting, the yarn is very rarely broken or damaged and, accordingly, the production of knitted fabrics of high and uniform quality is ensured.

In orcerthat tile invention may be fully understood various preferred embodiments will now be described byway of example and with referencetothe accompanying drawings, in which: Fig. lisa schematioview showing a knitting method in accordance with the invention; Fig. 2 is a partially sectional front view showing the main part of a knitting machine in accordance with the invention for knitting a circular knitted fabric; Fig. 3 is a schematic side view showing a process of yarn feeding; Fig. 4 is an enlarged front view showing the relationship between the small hole and the needle loop; Fig. 5 is an enlarged view showing the steps in the process of forming new loops;; Figs. 6 and 7 are a perspective view and a sectional side view, respectively, showing the feeding of yard into primary loops; Figs. 8 and 9 are views similarto Figs. 6 and 7, showing a process to raise new loops; Figs. 10 and 11 are views similarto Figs. 6to 9, showing a loop form-trimming process; Fig. 12 is a perspective view of the main part of another embodiment of knitting rnachinefora double knit; Figs.. 13 3 and 14 area partially enlarged plan view and a partially enlarged sectional front view respectively, showing the knitting process for producing double knit;; Figs. 1 5 and 16 are front views showing other means of successively feeding required lengths of Varn.

Fig. 17 its a partial front view showin a different embodiment of meansforlowering the knitted fabric; and, Figs. 18-a. 18-b, 19 and 20 are explanatory views showing still anotherembodimentusing an auxiliary nozzle.

Fig. 1 demonstrates a standard method of circular knitting according to this invention and Fig. 2 is a view schematically showing the main parts of a circular knitting machine for performing the method according to this invention. Acylincler 2 having a vertical axis of rotation Yis provided in the centre of the circular knitting machine and a multiplicity of small holes 3 ... 3 are provided in a row around the circumference ofthe cylinder 2 at intervals each equal to the distance between the wales of the fabric N to be knitted.Any suitable means may be provided for rotating the cylinder 2, for example, a flange member 4 holding the top end of the cylinder 2may be mounted on the machine frame by means of a bearing and can be rotated ata predetermined speed by rotation of a toothed wheel 6provided ontheflange member4and driven by a reduction motor M through an intermediate toothed wheel 7. At specific positions Facing certain ones 3A of the small holes in the cylinder 2, that is, positions forfeeding the yarn to the course, yarn-iFeeding air nozzles 8whose tips are directed towardsthesesmall holes 3A are provided. Furth- ermore, ejector air nozzles 9 directed towards specific other ones 3B ofthe small holes are arranged in positions radially inwardly of the yarn feeding positions and in the direction towards which the cylinder rotates. These two kinds of nozzle 8 and 9 are stationary and positioned at equal intervals correspondinglyto the number strands offed yarn (the number of courses included in one round of the circular knitted fabric).Control valves 10 are opened or closed in accordance with the predetermined knit formation program so as to jet air intermittently through the nozzles. Ayarn feeding zone 11 comprises rollers l4for intermittently feeding the yarn 13 in constant lengths (each length corresponding to a loop to be formed) drawn from a cheese 12, as shown in Fig. 3, and yarn tension controllers 15 and 15'. The yarn 13 delivered bythefixed length feed rollers 14 is guidedintotheyarn-feedingnozzle8throughtension controller 15' so as to be subjected to an airjetfrom an air pipe 1 and thus blown,togetherwith the air, towards the small hole 3A.As shown in Fig. 4, the internal diameter D of each ofthe small holes 3 of the row in the cylinder 2 is determined according to the internal diameter D1 of needle loops 17 of the knitting to be formed and the thickness of the knitting yarn 13.

For example, in the case of a standard plain knit cotton fabric having 16.5 courses per cm and 14.6 wales per cmand knittedbyayarn of yarn counts30S,the internal diameter D ranges from 0.35 to 0.40 mm, in otherwords is approximately equal to the internal diameter D1 of the needle loop.

The process of knitting bythe use of the abovementioned circular knitting machine will now be described. At the start of knitting, either a cylindrically formed circular knitted fabric that has been formed on another existing knitting machine and having a wale pitch equal to the distance between the small holes in the cylinder 2, or a cylindrical knitted fabric that has been prepared for initial knitting, knitted of synthetic resin filaments, and provided with needle loops aligned in the direction ofthe course along the top of the piece and subjected to heat setting, is fitted on to the outer periphery of the cylinder 2.Then, the needle loop atthe end of the course in the line of needle loops in the top position is matched upwith the small hole 3A positioned opposite the yarn-feeding air nozzle 8 so as to press the fitted fabric for setting by means of a pressing roller 18 disposed belowthe yarn-feeding air noule 8. Then, the yarn 13 is drawn from the cheese 12 and is inserted into the yarn-feeding air nozzle 8, whereupon theyarn end is caught up by the adjacent needle loop and the tension in the drawn yarn 13 is adjusted. Upon completion ofthe preparatory operation, following actuation of the compressor (not shown) a nd and confirmation of the correct air pressure, the knitting machine is started up.With the start of operation ofthe knitting machine, the fixed yarn length feed rollers 14 are rotated so as to feed the yarn 13 in predetermined lengthstothe end of the yarn-feeding nozzle8 and, atalmostthe sametime, the control valve 10 is instantaneously opened, whereby compressed air is jetted from the yarnfeeding nozzle 8towards the centre of the small hole 3A and the predetermined length ofyarnfed bythe feed rollers and formed into a loop is delivered from the tip oftheyarn-feeding nozzle 8 and is blown through the small hole 3A (see Figs. 5, 8and 9).With each feeding of a predetermined length of yarn by the feed rollers 14, the cylinder 2 rotates a small amount equal to the wale pitch and a roller 19 beneath the nozzle 8 rotates slightly so as to lower the knitted fabric N a small amount. The lowering distance is determined by the angle of inclination ofthe course running spirally in the knitting in the same manner as in the conventional circular knitting machine. For example, when the number of yarn feeding points provided around the periphery of the cylinder 2 is 40, the knitted piece is lowered by a distance equal to one pitch ofthe course during 1/40 revolution ofthe cylinder 2.Thus, with intermittent and successively continuing feeding of lengths ofyarn, each required forthe formation of a needle loop and sinker loop, by means of feed rollers 14, as well as with the continuousfeeding of compressed air into the yarnfeeding nozzle 8 in response to yarn feeding, and with successive rotations ofthe cylinder 2 through a distance equal to the spacing between two of the small holes 3 with every airjetyarn feed from the nozzle8, new loops 23 ... 23 are formed ion a laid-down attitude after being blown through primary loops 22... 22 atthe top end of the knitted fabric N and through the small holes 3... 3 positioned behind the primary loops 22, as shown, in Figs. 5,6 and 7. The primary loops gradually move downwards from their positions overlying the small holes 3 with the rotation ofthe cylinder 2 and with the lowering ofthe knitted fabric N. When the top end of a primary loop 22 reaches a position where it is belowthe small hole 3, compressed air is jetted from an ejector air nozzle 9 disposed inside the cylinder so thatthe associated new loop 23 in that small hole 3 is blown backth rough the hole towards the outside of the knitted fabric N. Preferably, air is jetted upwards by a loop-raising nozzle 24 from below from adjacent to the completed courses of the knitted fabric Ntowards the new loop 23 to push this new loop 23 outwards and upwards and position it around the outer periphery of the small hole 3.Afterwards, as shown in Figs. 10 and 11, by providing an airflow of an appropriate intensity to act upon the new loop 23 at the top thereof to apply a slight pressure in a downward sense by means of a formtrimming nozzle 25, the new loop 23 can be exactlytransformedfrom oblong to circular in shape so thatthe eye of the loop conforms to the shape ofthe small hole 3. In this way, the formation of a circular plain knit is achieved by continuous repetition of this action as described above for every course according to the predetermined knitting program.

Yarn feeding is performed intermittently by providing for vertical oscillatory movement of a positionally movable roller 1 5a relative to two stationary rollers 1 5'b and 1 5'b of the tension controlling means 15' positioned on the yarn-outgoing side ofthe fixed yarn length feed rollers 14. The frequency of the oscillatory movement is synchronised with the time required for movement between wales.

The knitting method according to this invention is particularly advantageous in its application to a knitting machineforforming a single knit of simple structure as described above. However, it is not limited to this application, and is applicable also to the formation of circular double knits such as rib knitand interlock knit, warp knit, or weft knit.For forming a double knit, as schematically shown in Figs. to 14, the aforesaid cylinder 2 is replaced buy a disc-like inner ring 31 provided with a multiplicity of small holes holes 30 axially drilled adjacent to the outer periphery thereof at intervals each equal to the distance between wales, and an outer ring disposed around the inner ring 31 with a gap S therebetween equal in width to the thickness of the double knit 32. The outer ring 34 has the same number of small holes 33 as the inner ring, drilled axially adjacent to the inner periphery thereof. Both rings are rotatable and arecoaxially arranged relative to a common axis so as to be synchronised in their movement.All the loops in the top row on the rig ht side of the double knitto be used for initial knitting and those in the top row on the reverse side are set in positions opposite to the small holes 33 in the outer ring 34 and the small holes 30 in the inner ring 31 respectively. Yarn feeding elements are provided above the inner ring 31 and the outer ring 34, and air nozzles 8 are provided above the gap S. The tips ofthe air nozzles 8 are oscillated in the space between the small holes 30A and the small holes 33A lying nearest each other in specific positions on the inner ring 31 and the outer ring 34 respectively, so as to turn alternately toward these holes 30 and 33 in association with the movement of the rings 31 and 34.

Priorto yarn feeding, primary loops 36 and 37 to be laid on the right side and the reverse side respectively, are separated by, for example, a separating rod (not shown) so as to be aligned with the positions of the small holes 30 and 33. In the meantime, predetermined lengths of the yarn 38 are successively, fed, togetherwith air, from the yarn-feeding nozzle 8 alternatelytowards small holes 30 and 33 of the inner and outer rings 31 and 34 respectively, so that needle loops 39 and 40 are formed in these holes 30 and 33 respectively and, atthe same time, new loops are formed in succession in primary loops in a row as the knitted piece is gradually lowered by gentle rotation of the inner and the outer rings 31 and 34 respectively.

New loops positioned in the small holes 30 and 33 after passing through primary loops are gradually drawn up by the aforementioned lowering ofthe knitted piece and are pushed upwards in a position immediately before reaching the subsequent yarn feeding end by the force of airjetted from the ejector nozzle (not shown) as in the previous embodiment, and then the loops are successively positioned around the small holes 30 and 33 ofthe inner and outer rings 31 and 34 respectively, when separated by the separating rod, so as to be laid down to the right and to the left, thereby enabling subsequent yarn feeding and knitting. Successive repetition ofthis perform ante makes itpossibletocreateadoubleknit.

In applying the knitting method according to this invention to warp knitting, a yarn-feeding nozzle is used instead of the reed fixed to the conventional warp knitting machine. By feeding the yarn into primary loops while reciprocating this nozzle to the right and to the left and gradually lowering the knitted piece, knitting is made possible. Since the major devices include a bed provided with lined holes each small in diameter as required, yarn feeding nozzles which are movableto the right and to the left, feed length control means, and lowering control means for the knitting,the mechanism and the movements ofthe machine are far simplerthan those of the conventional warp knitting machine where the yarn is lapped on the needle.

Further, when the knitting method according to this invention is applied to a weft knitting machine, an intermittent yarn feeding, that is, feeding to every other course, may satisfy the purpose. The yarn feeding parts comprising yarn-feeding nozzles, fixed yarn length feeding mechanisms, and tension control mechanisms are installed so asto reciprocate in the direction across the knitting. The knitted piece is lowered by a distance corresponding to one course pitch afterthe formation of one course; yarn feeding is stopped once the feeding parts both reach selvages of the knitted piece; and feeding is started again with the return ofthefeeding parts after raising new loops.

The diameterofthe opening at the tip of the yarn-feeding air nozzle with this invention is smaller than that of the small hole lying opposite thereto. For example, it measures about 0.25 mm for knitting yarn of cotton whose count is 30 or40s, whereby airflow is jetted linearly at a speed of about 2,000 m/min during yarn feeding and functions to feed the predetermined length of yarn into the small hole. Such an extremely small diameter ofthe yarn-feeding nozzle causes a problem ifyarn containing knots is used. However, this problem may be solved by the use of a cheese wound up by a winder equipped with knot-less yarn splicing devices utilising airflow.

As a method of successively feeding fixed lengths of yarn to the yarn-feeding nozzle, one can continuously draw the yarn 13 from the cheese while clamping the yarn between a constant length feeding tape 41 of speed-adjustable type and a reel 42 as schematically shown in Fig. 15, or else use a continuous delivery method as shown in Fig. 16 in which constant lengths of are delivered while flexing and reserving a yarn length as required by a pair of meshing toothed wheels 43. When a cotton yarn is used, the occurence of snarls is prevented and plasticity of the yarn is improved by having a high moisture content thereof, imparted by water absorption. Afavourable exact formation of loops istherebyensured.

In the application of the method according to this invention,the correct positioning of the primary loops around the small holes and high accuracy in the lowering movement ofthe knitted piece are important. Positional adjustment of the primary loops may be enhanced, for example, by a slight protrusion ofthe surrounds ofthe small holes 3. This can be produced by depressing the part surrounding each small hole or providing a similar protrusion without depressing the surrounding area. This serves for proper positioning of a new loop drawn from the protruding small hole or to keepthetip ofthe raised loop in a proper position by rollers, whereby continuous yarn feeding is made possible by keeping the loop in a proper position. As a means for lowering the knitted piece, for example in the case of a large number offeeding ends on the cylindrical piece of fabric, as shown in Fig. 17, a lowering roller 19 is supported by an arm 44 pivotally fixed at one end thereof in every yarn feeding position.

An adjusting screw 45 is provided on the other end of the arm 44 so as to permit adjustment ofthe inclination of the lowering roller 19, and the knitted piece is lowered after matching the inclination of all the lowering rollers 19 to conform to the inclination of the course ofthe knitting with respect to the line of small holes3 determined by the course pitch.

Another embodiment using an auxiliary nozzle 46 will be described hereinafter.

According to the knitting method ofthe present invention,yarn feeding, when performed intermittently, is such thatthe yarn is blown only when the tip of theyarn-feeding nozzle 8 is facing the eye of the primary loop 22, in other words it is blown when the primary loop 22 is moved sideways by rotation ofthe cylinder and the tip of the yarn-feeding nozzle 8 faces a space between two loops.

It is within the knitting method ofthe present invention to replace the above-described intermittent yarn feeding by a continuous yarn feeding in which the yarn in fixed lengths is successively blown, togetherwith air,fromtheyarn-feeding nozzle 8.

In this case, the straightforward application of continuous yarn feeding using airflow causes no problem when the yarn for a new loop 23 is blown and inserted into the circular hole of the nozzle which can be seen through from the inner part of the primary loop, but causes stay ofthe yarn fora new loop between primary loops 22 and 23 since yarn feeding continues even when the tip of the yarn-feeding nozzle 8 is positioned between two primary loops 22.

However, in the loop formation using airflow, almost no winding tension is exerted, and therefore the shape ofthe loop is approximately circular in the knitted fabric as shown in Fig. 18-a in which adjacent loops generally abut each other, whereby the distance between loops is shorterthan in the fabric N' knitted byordinaryknitting needles as shown in Fig. 18-b.

Therefore, in this case, an auxiliary nozzle 46 emitting air only is provided near the yarn-feeding nozzle 8 ata distance from it equal to one half of the distance between wales, as shown in Figs. 19 and 20, utilising the above-described characteristics of the yarn feeding method using airflow, so that the yarn as a new loop staying between primary loops 22 and 22 is drawn into the circular hole 3 by airflow having a pressure higherthan that in the yarn-feeding nozzle 8.

In the case of this example, when the yarn in the yarn-feeding nozzle 8 is aligned with the eye of the primary loop 22 (shown in Fig. 20), the auxiliary nozzle 46 emits air onlytowards a space between two primary loops 22 and presses a sinker loop in the previouslyformed wale immediately adjacentto a new loop with air pressure, thereby preventing a reverse direction flow or movement ofthe previously formed loop.

Auxiliary nozzles are provided in a number amounting to one or more and the air pressure is adjustable to an appropriate degree.

The knitted fabric moves downwards by a distance equal to the dimension ofonecoursewhilerotatingto the subsequent yarn feeding end after the formation of new loops, and, as a result, new loops are pulled by primary loops 22 and the yarn of a new loop is prevented from movement.

In this way, continuous yarn feeding permits the omission of complicated mechanismsforintermittent yarn feeding and the application, using simple struc tureofa knitting method using no needles.

Claims (12)

1. A method of forming a knitted fabric in which new loops are formed in succession by blowing required loop lengths of continuous yarn together with airthrough nozzles into primary loops in the preceding course.

2. A method offorming a knitted fabric as claimed in claim 1, wherein said method includes the steps of: feeding a yarn in a predetermined length to the end ofayarn-feeding nozzle; jetting compressed airfrom the yarn-feed ing nozzle towards the centre of a small hole around which a primary loop is positioned; delivering the predetermined length of yarn from thetip of the yarn-feeding nozzle to the hole to form a new loop; and displacing the knitted fabric a distance equal to wale pitch with feeding of a predetermined length ofyarn.

3. A method offorming a knitted fabric as claimed in claim 2, wherein said method further includes the step of jetting compressed airfrom an ejector air nozzle disposed atthe rear side ofthe hole confronting theyarn-feeding nozzle when the knitted fabric is displaced and lowered to a position where the top end ofthe primary loop is belowthe hole.

4. A method of forming a knitted fabric as claimed claim 3, wherein said method includes the step of jetting air from the direction towards which the knitted fabric is lowered towards the new loop to raise the new loop and to position it around the outer periphery ofthe hole.

5. Amethodofforming a knitted fabric as claimed in claim 4, wherein said method includes the step of causing an airflow to act upon the top end ofthe new loop so that the new loop becomes exactly circular in shape.

6. An apparatusforforming a knitted fabric comprising a cylinder having a multiplicity of small holes which are provided in a row around the circumference ofthe cylinder at intervals each equal to the distance between wales ofthe fabric to be knitted, meansfor rotating the cylinder, yarn-feeding air nozzles having tips directed towards the holes, ejector air nozzles directed towards the holes and arranged in positions radially inwardly of the yarn feeding positions and in the direction towards which the cylinder rotates, said yarn-feeding noules and ejector air nozzles jetting air intermittently, and yarn-feeding means for supplying yarn to the yarn-feeding nozzles intermittently in lengths corresponding to the loops to be formed.

7. An apparatus as claimed in claim 6, wherein the internal diameter of each of said holes is approximate ly equal to the internal diameter ofthe needle loop.

8. An apparatus as claimed in claim 6 or7, wherein rollersforloweringthe knittedfabricareprovided confronting the periphery of the cylinder.

9. An apparatus as claimed in any of claims 6 to 8, which includes loop-raising nozzles for jetting airfrom the direction towards which the knitted fabric is lowered towards the new loop, and nozzles for causing an airflowto act upon the new loop atthetop thereof.

10. An apparatus for forming a knitted fabric comprising a cylinder having a multiplicity of small holes which are provided in a rowaroundthe circumference of the cylinder at intervals each equal to the distance between wales of the fabric to be knitted, means for rotating the cylinder, yarn-feeding air nozzles having tips directed towards the holes, ejector air nozzles directed towards the holes and arranged in positions radially inwardly of the yarn-feeding positions and in the direction towards which the cylinder rotates, said yarn-feeding nozzles and ejector air nozzles jetting air intermittently, yarn-feeding means forsupplying yarn to the ya rn-feeding nozzles con tinuously, and an auxiliary nozzle foremitting air adjacent to each yarn-feeding nozzle at a distance therefrom equal to one half ofthe distance between wales.

11. A method offorming a knitted fabric substan- tially as hereinbefore described with reference to the accompanying drawings.

12. Apparatusforforming a knitted fabric substantially as hereinbefore described with reference to the accompanying drawings.