US3911698A

US3911698A - Thread feeding device for inserted weft knitting machines

Info

Publication number: US3911698A
Application number: US484650A
Authority: US
Inventors: Richard L Walford
Original assignee: JP Stevens and Co Inc
Current assignee: JP Stevens and Co Inc
Priority date: 1974-07-01
Filing date: 1974-07-01
Publication date: 1975-10-14
Anticipated expiration: 1992-10-14
Also published as: GB1519622A; DE2529126A1; IT1039546B; DE2529126B2; CA1028164A; AR207987A1; BR7504127A; ATA505875A; IL47603A; AU8260875A; JPS5123353A; AT341066B; DE2529126C3; NL7507811A; FR2277167B1; FR2277167A1; CH594766A5

Abstract

Elastic yarns are fed to knitting machines by measuring predetermined amounts of the elastic thread or yarn, which otherwise would be non-uniform in length or degree of stretch because of the high and not always uniform elasticity of the yarn. There are two distinct variants. Both variants include feeding out from yarn packages by driving the yarn package by friction on its surface. The first variant is for a weft knitting machine, such as a circular knitting machine, and in it a package of elastic yarn is moved along the needle line with a drive roller in contact with its surface, which roller turns as the package moves. The speed of the roller determines length of the elastic yarn paid out. Knitting is either by a non-elastic yarn which knits around the paid-out elastic yarn in the case of single knit machines, or in the case of double knit machines the paid-out elastic yarn may be sandwiched between the two layers of the double knit. The second variant deals with a multiple-package filling-thread-feeding device for warp knitting machines of the so-called ''''carousel'''' type in which thread from a plurality of packages, which are moved around by an endless chain, is fed to transfer chains provided with pins which carry the filling or weft threads to the knitting line, the motion of the packages stringing successive filling thread lengths from the pins on one chain to the pins on the other, and which provides for intermittent tensioning devices for the thread, for example spring-pressed discs, the tension being applied to the thread as it is clamped by the pin on one chain, then the tension releases, for example by a cam, until just before reaching the corresponding pin on the second chain and the tension is reapplied. The threading device is modified for feeding elastic yarn preferably by providing the yarn package, having a hollow core, with means for preventing rotation of the core for a portion of the travel of each package from carrier chain to carrier chain, the means preferably which apply a brake to the inside of the hollow core and cam which raises each package during a portion of the stringing from chain to chain which releases the braking means and permits rotation of the cores. The cams are of suitable length so that the elastic yarn is paid out a desired amount. The packages are moved along the cam and are turned thereby. In the unbraked portion of the travel a predetermined length of elastic yarn is paid out. Braking permits a predetermined stretch of the yarn. Instead of a large hollow core, packages may be on spindles to which intermittently brakes may be applied by any suitable means.

Description

United States Patent [191 Walford Oct. 14, 1975 THREAD FEEDING DEVICE FOR INSERTED wEFr KNITTING MACHINES [75] Inventor: Richard L. Walford, Bloomfield,

[73] Assignee: J. P. Stevens & Co., Inc., New York,

[22] Filed: July 1, 1974 [21] Appl. No.: 484,650

Primary ExaminerRonald Feldbaum Attorney, Agent, or FirmRobert Ames Norton; Michael T. Frimer; Saul Leitner [5 7] ABSTRACT Elastic yarns are fed to knitting machines by measuring predetermined amounts of the elastic thread or yarn, which otherwise would be non-uniform in length or degree of stretch because of the high and not a]- ways uniform elasticity of the yarn. There are two distinct variants. Both variants include feeding out from yarn packages by driving the yarn package by friction on its surface. The first variant is for a weft knitting machine, such as a circular knitting machine, and in it a package of elastic yarn is moved along the needle line with a drive roller in contact with itssurface, which roller turns as the package moves. The speed of the roller determines length of the elastic yarn paid out. Knitting is either by a non-elastic yarn which knits around the paid-out elastic yarn in the case of single knit machines, or in the case of double knit machines the paid-out elastic yarn may be sandwiched between the two layers of the double knit. The second variant deals with a multiple-package filling-thread-feeding device for warp knitting machines of the so-called carousel type in which thread from a plurality of packages, which are moved around by an endless chain, is fed to transfer chains provided with pins which carry the filling or weft threads to the knitting line, the motion of the packages stringing successive filling thread lengths from the pins on one chain to the pins on the other, and which provides for intermittent tensioning devices for the thread, for example springpressed discs, the tension being applied to the thread as it is clamped by the pin on one chain, then the tension releases, for example by a cam, until just before reaching the corresponding pin on the second chain and the tension is reapplied. The threading device is modified for feeding elastic yarn preferably by providing the yarn package, having a hollow core, with means for preventing rotation of the core for a portion of the travel of each package from carrier chain to carrier chain, the means preferably which apply a brake to the inside of the hollow core and cam which raises each package during a portion of the stringing from chain to chain which releases the braking means and permits rotation of the cores. The cams are of suitable length so that the elastic yarn is paid out a desired amount. The packages are moved along the cam and are turned thereby. In the unbraked portion of the travel a predetermined length of elastic yarn is paid out. Braking permits a predetermined stretch of the yarn. Instead of a large hollow core, packages may be on spindles to which intermittently brakes may be applied by any suitable means.

5 Claims, 11 Drawing Figures US. Patent oct.14,1975 sheetlom 3,911,698

Sheet 2 of 4 US. Patent Oct. 14, 1975 m 'lll 25 \H l W Illn HUN US. Patent Oct. 14, 1975 Sheet 3 of4 3,911,698

US. Patent Oct. 14, 1975 Sheet 4 of4 3,911,698

THREAD FEEDING DEVICE FOR INSERTED WEFT KNITTING MACHINES BACKGROUND OF THE INVENTION Knitting machines and preferably warp knitting machines with inserted weft or filling threads at the knitting line have achieved great commercial success because of the enormous speed possible on the knitting machine as compared with an ordinary loom for weaving. The feed of wefts to a warp knitting machine presented a serious problem because of the great speed of the machine and hence the speed with which thread is taken from a package. The thread or yarn which constitutes the weft is carried to the knitting line, as is conventional in warp knitting machines, bya pair of chains with pins or clips. The thread as it passes the first chain is grasped by an open clip which then closes, normally under spring pressure, and the thread then strings across to the second chain, where the clipping of the pins is repeated, and normally after grasping the thread it is cut, leaving an end. If a single package is used, the thread is fed at speeds reaching 100 miles per hour and more, if the machine is to be used at the maximum speed that the other elements would permit.

A few years ago an important advance was made, which is described in the Carman US. Pat. No. 3,364,701. In this patent a large number, for example 12, 24 or more, of packages of weft thread were moved around on an auxiliary chain and strung from one conventional carrier chain to another, which chains, as mentioned above, carried the length of weft thread to the knitting line. Speed of thread feed was greatly reduced, and different threads, for example different colors, were possible to produce special patterns where desired. Because of the moving around of the package on their auxiliary chain this device is known in the industry as the carousel type of feeding device, and this name will be used in much of the following specification to save awkward language.

Some problems arose because the carousel machines had to carry a tensioning device along with each package because unless the yarn is under suitable tension it will not be strung out between the carrier chains uniformly without sagging. Tension is actually only required when the thread is first attached to a pin on the first carrier chain and again as it approaches the pin on the second chain. However, when tension is maintained throughout the whole stringing there is considerable strain on the thread, and this raises various problems, such as lint formation and the like. Also, the friction may limit the speed of feeding, particularly with relatively fragile threads or yarns.

An improvement on the Carman carousel is described and claimed in the Jones U.S. Pat. No. 3,636,731, Jan. 25, 1972. In this improved machine tension to the yarn as it is strung from carrier chain to carrier chain is applied only for short periods adjacent each of the chains and the rest of the stringing is tension free. For example, this is effected by a cam on the frame of the machine which releases tension, for example if a preferred springpressed disc tension means is used, by raising a rod with a wedge-shaped end that separates the disc against spring pressure. The Jones intermittent tensioning represented a marked improvement which permitted feeding at maximum speed and minimizing strain on yarn, lint formation, and the like.

Although the Jones device represented an important practical improvement on the original Carman carousel, it was still only useful with yarns which did not stretch readily. Inserted-weft warp-knit fabrics are often desirable with elastic weft yarns, which can produce one-way stretch fabrics if only the weft is elastic or two-way stretch if the warp yarns which are actually knit are also elastic. Such fabrics were not practical on the Jones device, and this left elastic knit fabric to other less efficient and complex feeding configurations. One variant of the present invention deals with an improvement to the Jones knitting machine feed, which improvement permits the use of elastic wefts.

SUMMARY OF THE INVENTION The present invention has two variants which, while they have a common feature, are very different in their construction. The first variant is for a weft knitting machine of the single or double knit type, such as a circular knitting machine, which will be the form later on first specifically described, although it will be pointed out that the same features may be used in a weft knitting machine in which the needles are in a straight line and the feed of the weft is first in one direction across the needles and then reversed again across them in the opposite direction and so on. In the variant applying to weft knitting machines, a package of elastic yarn, or if multiple yarns are needed more than one package, is moved along the needles, for example around the periphery of a circular knitting machine. The knitting takes place with non-elastic yarns and may be either single or double, but, as will be pointed out below, the elastic weft yarn is laid out by the same means.

As the yarn package or packages move along the needles the package is turned by friction of a driving roller or face driven, which causes it to pay out the elastic weft yarn at a predetermined rate, i.e., a predetermined length of elastic yarn for each revolution of a circular knitting machine or movement of the package across the needles in the case of a straight knitting machine. The paying out of the yarn is not under tension because the surface of the package turns with the peripheral speed determined by the diameter of the driving roller.

It is often desired to have an accurate predetermined tension on the elastic yarn. This has been impractical in the past with extremely complicated and expensive mechanisms. In the variant of the present invention dealing with weft knitting machines, an exact predetermined tension may be imparted by having the roller pay out elastic yarn at a slower rate than the movement of the yarn package. While the amount of yarn paid out for a particular rotation of the drive roller is constant, if the roller pays out elastic yarn at a slower rate than the movement of the yarn package along the needles, an exactly determined stretch results. In many weft knitting machines where it is desired to have a certain stretch in the final fabric it is usually essential that this amount of stretch be uniform. If it is attempted to produce a stretch in the fabric by moving elastic yarn through tension devices, uniformity is impossible because there is no such thing as an elastic yarn of absolutely uniform stretchability throughout its whole length. The present invention produces the completely uniform desired degree of stretch with the simplest of mechanisms, which permit maximum speed of the knitting machine. This solves an important element of the stretch problem for high speed use because if tension is used and the yarn is pulled through the tension de vice very rapidly, the friction is high and variations in stretchability of the yarn become more serious. It has been stated above that very elaborate mechanisms would be required to provide uniform stretch. This is particularly true with elastic yarns such as Spandex, which is uncovered, a form of yarn which is desired in many knitted fabrics. Somewhat simpler operation has been effected with covered elastic yarns, where there is a covering of unelastic textile thread. This limits the amount of stretch irrespective of the stretchability of the elastic yarn itself; and therefore even if there are some differences in stretchability as the elastic yarn is fed to the knitting machine, it is practical to use covered elastic yarns. The present invention is useful with such yarns but does not have as great an advantage as the reduction in costs available is less, and of course there are great savings where uncovered elastic yarns are used in the fabrics where they are desired. This is applicable to many fabrics, some of which have not been produced with uncovered elastic yarns because of the excessive costs, and now this is feasible.

It has been stated above that the present invention in its variant for weft knitting machines is applicable to single knit or double knit. The actual mechanical situation in the fabric is, however, a little different. In the case of single knits, the non-elastic textile yarn which is knit is knit around the elastic weft. In the case of double knit fabrics, it is usually preferable to adjust the machine so that the elastic yam at constant, predeter mined stretch is sandwiched between the two layers of the double knit fabric. The operation of the weft knitting variant of the present invention performs essentially the same function. It should be noted that in the weft knitting machine predetermined stretch of elastic yarn is produced with only a single mechanical organi zation, that is to say, the driving of the yarn by a drive roller and the movement of the whole package. It should also be noted that as a package becomes used up some means must be provided to keep the roller in contact with the surface. This is extremely simple and can be affected by spring pressing the roller against the package. This involves relative movement of the package and the roller and it is theoretically immaterial which one is moved. However, as the roller has to be driven, simpler mechanisms are provided if the movement is of the yarn package rather than of the roller.

The second variant of the present invention deals with warp knitting machines. This is at present commercially the more important one. Here several additional functions are performed over the weft knitting machine, and the present invention finds its greatest commercial advantage in the warp knitting field. While, as will appear from the description below, both variants involve friction surface or face driven turning of the elastic yarn package, their mechanisms are very different; and therefore, as will be seen, the two variants are independently claimed in different sets of claims.

The preferred warp knitting variant of the present invention preferably uses a carousel type of warp knitting machine with the improvement of the Jones patent referred to above. The invention will be described in conjunction with a modified Jones machine in which the yarn packages are moved around by a chain on spindles, preferably extending horizontally as is described in the Jones machine rather than vertically as in the original Carman carousel, but the yarn packages are not of conventional construction, i.e., they are not packages which are mounted on spindles attached to the package carrier chains. If it is attempted to use the same design of standard yarn package that is illustrated in the Jones patent with elastic yarn packages, the yarn will stretch varying amounts because it is impossible to adjust tension so that with elastic yarn no stretch results or that a stretch of a predetermined amount results. Therefore, the Jones machine has not proven useful for feeding inserted wefts of elastic yarn or thread.

In the present invention there is provided one or more cams on the frame of the knitting machine, in addition to the cams which activate and deactivate the tension devices. These cams contact the yarn packages as they move past, causing the packages to turn and pay off a length of elastic yarn equal to the length of the cam. It is usually desirable to have more than one cam so that the paid-out lengths of elastic yarn are not too long. This is of importance as many warp knitting machines are very wide, for example up to inches. As a portion of the yarn is paid out, when it leaves the cam it is desirable to stop the rotation of the package for predetermined distances. This performs two functions. First, it catches up with any excessive slack produced by overshooting of the yarn paid off from the spinning packages and, more importantly, can impart a certain, exactly predetermined degree of stretch to the weft laid across from carrier chain to carrier chain of the knitting machine. While it is possible with a single cam surface to feed elastic yarn for the whole length of the weft in a completely relaxed form, it is often preferred to have this weft under a certain predetermined tension, and this is effected by braking the rotation of the package at predetermined points and for predetermined distances. This is best accomplished by having more than one cam.

The present invention in its broadest aspect contemplates any means of intermittent braking of the spinning packages at precisely predetermined points and for a precisely predetermined distance of package movement. This can be effected in many ways, for example by separate cams, solenoid operation, and the like. However, in a preferred embodiment the braking mechanism can be carried by each package itself. These braking mechanisms can be deactivated by the raising of the package as it mounts the entrance ramp of each cam and activated as it is lowered when it leaves the exit ramp. This is very simple, very economical of equipment, and is preferred. The description below, both in general summary and still further below in the description of preferred embodiments, will be in terms of such a modification.

In the preferred modification the package is of quite different design with a relatively large cross-section hollow core on which the yarn is wound. Inside this hollow core are means, preferably a spring attached to the yarn package carrying spindle and another shaft carrying a projecting brake shoe. When the packages are in their lowered position, that is to say not riding on a cam profile, the inner core cannot turn about the spindle and elastic yarn is strung in a stretched state and/or slack taken up. Then when each package encounters the cam or cams and is raised, this turns the shaft carry ing the brake shoe against spring pressure and allows the package to roll freely on the cam and to unwind its elastic yarn under substantially no pressure because, of

course, the cams are arranged so that the packages are raised when the intermittent tensioning means of the Jones machine is also released. By the choice of a particular length of cam or cams the elastic yarn can be strung from carrier into carrier chain at an accurately predetermined tension. Ordinarily when elastic fabrics are to be knit, the elastic weft is under some tension but the tension should be small so that the fabric does not pucker. The present invention permits stringing the elastic yarn at any desired very low tension, and this can be adjusted by the length of the package raising cam or cams and, therefore, permits stringing elastic yarn under the exact tension desired.

As has been described in the Jones patent, the intermittent tensioning can be effected by a number of .means. However, in the present case there will be described only the tensioning means actually set forth in the Jones patent because the particular tensioning means forms no part of the present invention. In referring to tensioning means it is, of course, not referring to the braking and relaxation of the elastic yarn packages but rather the spring-pressed discs with wedgeshaped rods shown in the Jones patent. The intermittent tensioning means of the Jones patent, which are used only for extremely short periods as the yarn is clamped onto the pins of each carrying chain, are in addition to the braking of the turning packages referred to above.

In the preferred variant of the present invention, i.e., with warp knitting machines, it is an advantage of the present invention that the knitting machine described in the Jones patent need not be extensively rebuilt since the modified yarn packages with hollow cores move over the frame of the knitting machine shown in the Jones patent and the additional cam or cams are readily attachable thereto and preferably should be detachably mounted, for example, by machine bolts, so that cams of various lengths can be provided depending on the particular elastic yarn which is to be fed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the weft feed transport and carousel in semi-diagrammatic form and illustrates the modification to the standard Jones machine;

FIG. 2 is a section along the line 22 of FIG. 1;

FIG. 3 is a section at right angles to FIG. 2;

FIG. 4 is a section along the line 4-4 of FIG. 2;

FIG. 5 is similar to FIG. 4 but illustrates a retracted cam follower;

FIG. 6 is a section through a yarn package, 91, showing the brake show in braking position;

FIG. 7 is a similar cross-section of package 9J with the package raised by the brake show releasing cam;

FIG. 8 is a diagrammatic illustration of a shaft and elements in FIGS. 6 and 7, the inner core of the yarn package being omitted for clarity;

FIG. 9 is a diagrammatic view of a variant for feeding elastic yarn in a weft knitting machine, and

FIGS. 10 and 11 are sections along the lines 10-10 and 11-11 of FIGS.-9 to 11 show only a part of the machine.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The variant of FIGS. 1 to 8, which deals with the application of the present invention to a warp knitting machine will first be described. FIG. 1 is a plan view modification made by the present invention. Being a plan view, the packages on the carousel are not all in one plane as the two weft carrier chains 1L and IR extend up at an angle from the plane of the carousel itself, these chains carry conventional clamping pins 2, which are opened on chain 1R as it is approached by the yarn, as will be described, and of course opened when the weft has been carried to the knitting line. The drawing does not extend this far and the knitting line is not shown as it is not changed by the present invention. The opening and closing of the clamping pins is by conventional cam means on the sprockets for the chains. It is not shown as it is not changed by the present invention any more than it was in the Jones machine. The operation is known and is illustrated in FIG. 5 of the above mentioned Carman patent, to which reference is hereby made for an illustration of this known mechanism. In other words, this portion of FIG. 1 is in purely diagrammatic form.

As in the Jones patent, this modified carousel portion is built on a frame 7 provided with an endless carrier in the form of two chains, a wider chain 5 on which the yarn packages are carried and a narrower chain 8 on which the tensioning devices for each package are carried. As can be seen from FIG. 1, the packages, which are numbered 9A to 9K, are horizontal; in other words in a modified carousel rather than the form in the original carousel patent mentioned above, in which the packages extend vertically. The Jones machine can be operated with vertical packages but the present invention, while not inoperative with vertical packages, is much less convenient and the horizontal package modification illustrated in the drawings and here described constitutes a definitely preferred form. The drive for the chains 1L and IR and for the

chains

5 and 8 is taken from the main drive for the knitting machine, as diagrammatically indicated at 6. The mechanical connections are not specifically illustrated as they would only confuse the drawings and are not changed by the present invention. Similarly, only the eleven packages which can be seen by looking down on the carousel are shown, but of course the

chains

5 and 8 are endless.

Each package has its own tensioning device, labelled 10A to 10K, the lettering corresponding with the packages. Yarn from the packages is numbered 11A to 1 1K and runs from each package to its tensioning device. Before describing the construction of the tensioning device and their auxiliary equipment, which are the preferred form of the Jones patent and also constitute the preferred but not limiting form for the present invention, the general operation will be described.

The

chains

5 and 8 move from right to left, as can be seen by the arrow around the shaft from the drive 6, and the chains 1L and IR move diagonally up. All the chains are, of course, endless and return, but in FIG. 1 the return is not shown. Packages 9A and 9K are turning around an end sprocket, (not shown), of chain 5. The mounting of the package on the chain includes a bracket 24 with a spindle 25 for each package. This spindle is not identical in design with the correspondingly numbered spindlein the Jones patent and, as can be seen in FIGS. 6 to 8, performs an additional function.

In the Jones patent the spindle is in the center of the yarn package, which is fixed on it in normal manner. In the present invention the spindle 25 is eccentric in the large hollow center of the inner package core, which is numbered 28 in FIGS. 6 to 8. This construction does not show in the plan view of FIG. 1. In order not to confuse FIG. 1, only one bracket 24 is shown at the right, and similarly only one bracket 26 for tensioning device 10A. The brackets 24 show the spindle 25 but, again, in order to avoid confusing the drawing this reference numeral is not repeated for each package.

It will be seen that only the tensioning device 10A is shown in section in FIG. 1. At this point it will be seen that yarn 11A from package 9A passes into and out of the tensioning device 10A through grommets 19, which have smooth ceramic surfaces. The passage of the yarn through the tensioning device is more clearly shown in FIG. 2 and wil be described in detail below. It will be seen that there are short tails 4 of the yarn extending from one of the grommets 19 in each tensioning device while similar tails are, of course, extending from the tensioning devices for the packages on the bottom or return of the chain 5. In FIG. 1 only three tails are shown.

Package 98 has moved to a point so that the tail is opposite a clamp or pin on the chain 1R. This pin has been temporarily opened by the well known cam, as is shown in FIG. 5 of the Carman patent. It is shown only diagrammatically in FIG. 1. There is a vacuum funnel 3 which pulls out the tail 4, and this is also conventional in all carousel machines and is shown only diagrammatically. As the chain 1R moves, the pin which has received the tail 4 moves off its sprocket and clamps the yarn. Of course, this has occurred with the tails of the preceding packages 9C to 90. As a result, yarns 12C to 120 are strung between the chains as the packages move. However, as will be described below, the yarn does not unwind from the packages throughout the whole of their travel as it does in the Jones machine. After package 90 has moved past chain 1L and has been clamped by the corresponding pin 2, which was opened and closed as has been described above in connection with the pin 2 which clamped onto the tail 4 on the right hand chain, a cutter 13 cuts the yarn, leaving a tail, which can be seen as 4 in the yarn from the package 90, which is getting ready to turn around the sprocket of the chain 5. Since the yarn in FIG. 1 is elastic yarn, a separate track extends beyond the cutter 13 to the left of where the packages move past the carrier chain IL. This somewhat shorter section of cam opens the clamping discs. Upon leaving the cam, the discs close and grip the yarn, after the slack has been taken up. This occurs just before severing by the cutter 13, which leaves a tail where the yarn is cut which is long enough to be sucked out by the funnel on package past the chain 1R, as has been described. If the yarn had been under tension at this point, it would have stretched and the tail would snap back into the package and so would not be available to be clamped by the pin on chain 2R as it goes past it. The mechanism of deactivating braking is described in detail below in conjunction with the description of FIGS. 6 to 8. The operation is exactly the same inthe short extent of cam 30 to the left of chain 2L.

As in the Jones machine, a cam 14 is mounted on the frame 7 with an entrance ramp just beyond the tensioning device C and an exit ramp just beyond the tensioning device ION. As FIG. 1 is a plan view, the gentle slope of these two ramps does not show. In addition to the cam 14, there are shown two cam sections 30 under the packages. Their operation will be described in more detail below. The length or lengths of the cams 30 can be varied, as has been mentioned, and it will be seen they are detachably mounted on the frame of the machine, being attachable at various points by bolts 33. These bolts fasten into a series of threaded holes in the frame but only two bolts are illustrated in FIG. 1 in order to avoid confusing the figure.

FIGS. 2 to 5 illustrate the intermittent tensioning devices of the Jones machine, which are present also in the present invention. They will first be described. It will be seen in FIG. 2 that the yarn enters through one grommet 19, passes around guiding rolls 23 and then between two discs 20. These discs are mounted on a bolt 21 and can move against the tension of the spring 22. This can best be seen in FIGS. 3, 4 and 5. FIG. 2 represents the position occupied by tensioning discs 10D in FIG. 1 and also in the same position for tensioning devices 10E to 100. A rod 15 can be seen to have been moved up by the cam 14. This rod moves in an extension 18 of the housing 10 against a spring 17 and is provided at its upper end with a wedge-shaped taper 16. The wedge shape can be seen more clearly in FIGS. 4 and 5. As the rod is forced up by the cam 14, it has separated the discs 20, as shown in FIG. 4, and therefore the yarn passing between the discs is not held by friction and can run freely. This is also the case with the yarn from tensioning devices 10E to 100, inclusive. As a result, yarns 12E to 120 are somewhat loose.

When a tensioning device reaches the exit ramp, which is the case with the tensioning device 10N, the rod 15 slides down the exit ramp 27 of the cam 14 under the urging of its spring 17. This is the position shown in FIG. 3 and in more detail for the discs in FIG. 5. The discs now grip the yarn 111 and there is sufficient tension so that it is straightened out until it is caught by the pin 2 on chain IL. The tension is sufficient so that yarn UN is pulled taut, and in the case of elastic yarns, as will be described below, usually somewhat stretched. It is caught by the clamping pin 2, and the chains 1L and IR then carry-these yarns in strict parallelism to the knitting line of the weft-insertion knitting machine. This line is not shown in FIG. I as it is not changed by the present invention or, as a matter of fact, by the Jones patent. As has been mentioned above, yarn is cut by the cutter 13, leaving a tail 4, which tail remains as package moves around to the position occuplied by package 9B, and the sequence of operation as far as stringing and intermittent tension is concerned is repeated as described above.

FIGS. 6 to 8 illustrate the new design of packages according to the present invention. This is quite different from the packages in the Jones patent, where the package holder is centrally located and does not rotate. On the contrary, as can be seen in FIGS. 6 and 7, the spindle 25 is eccentrically located. It is connected to an element 34 which turns on a shaft 29 on which a brake show 32 is mounted, which is best seen in FIG. 8. The element 34 is connected to the spindle 25 by a spring 31. When this spring is retracted, as can be seen in FIG. 6, it turns the shaft 29 and forces the brake shoe 32 into contact with the inside of the hollow core 28. This is the position shown in FIG. 6. In this position the package cannot turn, and so while in this position an elastic yarn is stretched. When the package moves on and climbs the ramp on the right hand cam 30, it is raised,

and this permits the spring 31 to elongate, which turns the shaft 29 in a direction to move the brake shoe 32 out of contact with the inside of the hollow core 28. This is the position shown in FIG. 7. FIGS. 6 and 7 are to relative scale and represent the relative height of the package in both positions.

In FIG. 7 the yarn package can turn freely, and the stretched elastic yarn then pulls out additional yarn until the yarn is substantially relaxed. As the packages move further on, they move off the exit ramp of the first cam section 30, which again applies the brake shoe 32, thus again locking the packages 9E and 9F against turning, and causes the elastic yarn to stretch again. When the packages then strike the somewhat longer cam section 30 at the left hand side, the entrance ramp 35, which is diagrammatically indicated in FIG. 5, again raised the package, releasing the brake shoe, and thereafter the yarn unwinds freely until the intermittent tensioning means 10I takes hold, whereupon it is pulled sufficiently taut so that it can be readily clamped by the pin 2 on chain IL. The position of the exit ramp 27 of cam 14 is shown a somewhat exaggerated distance from chain IL in order to make the drawing clearer. Depending on the particular elastic yarn which is to be strung, it may be considerably nearer to chain 1L. After the yarn is grasped by the pin 2, it, of course, stretches because the cam 30 does not extend further, and after cutting would retract to a shorter length. This might make for too short a tail 4, and that is the reason why the track on which cutter 13 is located is somewhat longer than in FIG. 1 of the Jones patent. Exact dimensions, of course, depend on positioning of the intermittent tensioning means and the nature of the elastic thread.

Theoretically it would be possible to have only a single cam 30. However, for smoothness of operation it is better to have two or more cams, which prevent excessive sagging while the packages are moving along the cam profile and hence unlocked and free to rotate. The number of sections of cam 30 can vary, and the present invention is not limited to there being a plurality and very definitely not limited to an exact number or length of cam section. However, as having a plurality of sections makes for smoother adjustment and operation, this is illustrated in FIG. 1. It will be noted as the packages climb the cams 30 they are raised somewhat against the tension of the springs 31. In FIGS. 6 and 7 for clarity the amount by which a package is raised is somewhat exaggerated since the brake shoe 32 needs to move only a short distance to set the core 28 free to rotate. It is desirable to have the cams 30 so adjusted as to give sufficient movement to reliably lock and unlock cores but not an excessive movement. It is also, of course, necessary that there be actual contact with the package. However, the weight of the package and its core is sufficient to provide this small amount of force.

FIGS. 9 to 11 illustrate the second variant, that is the application of the present invention to weft knitting. There may be weft knitting on a circular knitting machine or on a machine in which the needles are in a straight line. The circular machine operates with movement of the yarn feeding devices in continuous motion in one direction whereas, of course, if the needles are in a straight line the movement of feeding must be an oscillatory one first in one direction and then in the other. As has been mentioned above, this variant of the invention is applicable either to single or double knit fabrics. In each case the knitting is by one or two yarns which are not elastic. In the case of a single knit the non-elastic yarns knit around the laid-in elastic weft whereas in double knit the elastic weft may be laid as a sandwich between the two layers of double knitting. Since the present invention is concerned only with the feed of elastic yarn and not with the motion of the needles themselves, in order not to confuse the drawing only the feed mechanism is shown.

The drawings illustrate a yarn package with the large diameter core as in he first variant illustrated in FIGS. 1 to 8. The yarn package is numbered 9, which is the same reference numeral given in the other variant as, of course, the package itself is the same. As in FIGS. 1 to 8, the packages of elastic yarn have large central cores, which are also given the same reference numeral 28 as in the other figures.

FIG. 9 illustrates a stationary rim 52 on a circular knitting machine on which is mounted a chain 36 which is, therefore, stationary. The package is moved around the periphery in synchronism with the motion of the knitting needles 51, which motion is not changed by the present invention, and therefore the needles are not shown in detail in order not to confuse the drawing. This motion is effected by a drive from a pulley 53 turning in synchronism with the knitting machine drive, (not shown as it is not changed by the present invention). The pulley drives a shaft 54 journaled in a fork on the stationary part 52. At the other end of the shaft is a gear 55 which meshes with gear teeth on a movable rim 49 which turns around and inside the stationary rim portion 52. While the portions of the drive are shown in FIG. 10, the drive itself is best seen in FIGS. 9 and 11. In FIG. 11 the movable element 49 is shown broken away. It extends across to the needles and drives a conventional cam which successively moves the needles up and down. This drive is not changed at all in the present invention and is therefore not shown in detail on FIGS. 9 and 11 in order not to confuce the drawings.

The mo-vable element 49 carries a spindle or shaft 37 on which there is a pair of rollers 38 which contact the inner surface of the package form 28. Within the hollow form there is a second shaft 39 carrying a pair of rollers 40. The shaft 39 is connected to shaft 37 by two metal elements 41. FIG. 10 shows the two shafts clearly but the view of FIG. 9 is a plan view at right angles to FIG. 10. The

shafts

37 and 39 are shown in section rather than in elevation as in FIG. 10. However, FIG. 9 permits showing that the shaft 39 extends in a fork or slot 42. The shaft 39 is urged away from the shaft 37 by the spring 45.

A roller 43 is clamped to a spindle 44 by the set screws 46. This can be seen best in FIG. 10. Near the end of the spindle 44, which, as can be seen in FIG. 10, is journaled into the moving element 49, there is a gear 47 locked to the spindle with a set screw 48. This gear meshes with the stationary chain 36, as can best be seen in FIG. 9 since the chain does not show in FIG. 10. The spindle 44, to which roller 43 is locked, rotates as the gear 47 moves around the stationary chain 36. This also turns the roller 43, to which it is locked, and the roller in turn bears on the outside of the yarn package 9 causing the latter to rotate in a direction opposite to that of the spindle 44 and roller43. This is indicated by the arrows on FIG. 9. This causes elastic yarn to be paid out to the needles, as can be seen in the solid line on FIG. 9. This is the yarn which is laid in on the needles of the conventional circular knitting machine. As the paying out is to a predetermined length, which may be somewhat less than the peripheral travel of the element 49 along the knitting needles, the elastic yarn is always paid out a predetermined length, and if it is shorter than the peripheral motion of the element 49 along the knitting needles 51 it can provide a predetermined small amount of stretch where this is desired. In FIG. 9 only a single row of needles is shown, which would correspond to a single knit. If there is a double knit, involving another set of notches, as is conventional, there may be two supply yarn packages, which is also con ventional on double knit knitting machines. If both inlaid yarns are elastic, the second package may be the same as the first package shown in FIGS. 9 and 10 and the elements which cause paying out of the elastic yarn, i.e. drive of a movable element with gear and stationary chain, are repeated. They are not shown in drawings as they would confuse the drawings unnecessarily.

The surface of the package 9 is in contact with the roller 43 and is rotated by it. As can be seen on the drawing, the spring 45 urges the shaft 39 away from the shaft 37, which is for the purpose of maintaining firm contact with the roller 43 as the thickness of yarn in the package changes when it is unwound. As can be seen in FIG. 10, the roller 43 carries a shoulder 50 on which the yarn package turns. This permits turning but does not permit the package to slide down so that it is held in contact with the roller 43 at a predetermined level. When, however, a new package has to be supplied the old package can be slid up and a new package slid down. At all times when the machine is operating the spring 45 maintains the surface of the yarn in contact with the roller 43. Of course when a new package is mounted the shaft 39 slides back in the slot 42 comprises the spring 45.

The rate at which yarn is unwound from the package 9 is determined by the number of teeth on the gear 47 and of course by the diameter of the roller 43. This pays out a constant length of elastic yarn. For most circular knit fabrics it is desirable to have the elastic weft laid under small tension, which can be varied depending on the nature of the fabric desired. This is effected by the number of teeth on the gear 47 and diameter of roller 43. As can be seen rom FIG. 10, it is a very simple matter to mount gears of different diameters and teeth numbers to change the rate of paying out of the elastic yarn to produce the desired amount of tension. The slower the roller 43 turns the greater the tension on the elalstic yarn because it moves around the circular knitting machine at constant speed, and if it is paid out more slowly this results in the predetermined stretch. However, this is in no way affected by any nonuniformity of stretch of the elastic yarn but solely by relative peripheral speed of the roller 43. Therefore, the tension is always constant at the figure which is predetermined for a particular fabric. This is just as true with uncovered elastic yarns such as Spandex yarn as with covered yarns. As a matter of fact, the present invention presents much more advantage with uncovered yarans because, as has been generally described above, it is possible to use other mechanisms with covered yarns. This permits various decorative patterns because the Spandex yarn, which may be white or dyed a desired color, does not show in the knitted fabric, whether single knit or double knit, but if the fabric is stretched the elastic weft can be seen. This kind of effeet can be very atractive and is desired in many cases for knit stretch fabrics.

The drive of the packages is very simple and quite positive and the mechanism for maintaining constant contact with the roller 43 is also very simple and very reliable. This makes for a very economical structure for feeding elastic yarn in a weft knitting machine.

I claim:

1. In an elastic weft thread feeding device for warp knitting machines comprising a first and second endless carrier with yarn clamping means thereon for opening and closing to clamp on weft thread, a third endless carrier provided with a plurality of yarn packages, each package having associated with it and moving therewith a tensioning means which, with elastic yarn, act as gripping means for the yarn, the endless carriers being synchronously driven and positioned so that as a package comes adjacent to the clamping means on the first carrier the means opens, clamps the yarn from the package, and then strings out the yarn as the package continues to move, the tensioning or gripping means being provided with means for applying pressure to the yarn intermittently to hold the yarn as it is grasped by the clamping means on the first carrier, maintaining gripping for a short distance beyond, the pressure then being released until the package approaches the clamping means on the second carrier and reactuated for a short distance as the package transfers its yarn to said clamping means on the second carrier, the yarn being tension free during the major portion of the travel of each package between carriers, the impovement which comprises means for producing relative motion between packages having yarns that are elastic and a surface whereby the packages are rotated and yarn is unwound therefrom under substantially no tension, and means for intermittently braking the rotation of the yarn packages for sufficient periods to string the yarn from carrier to carrier in predetermined length when relaxed and at a predetermined tension, cutting means for cutting the elastic yarn after the package has passed the second carrier chain, and means for producing relative motion between the package and the surface, the package being free to turn, whereby a predetermined amount of yarn is wound off under substantially no tension and a tail is formed from the package of suitable length for clamping to the first carrier chain when the package passes across it.

2. A weft thread feeding device according to claim 1 in which the yarn packages are carried on hollow cores of relatively large internal diameter, each package having within the hollow core a spindle attached to the third endless carrier and a second shaft connected to the spindle by spring means and carrying a brake show adapted, when the spindle is in its lowest position, to turn the shaft and apply the brake shoe to the inside of the hollow core, thereby locking the package against rotation, and means actuated by movement of the packages for raising the packages sufficiently to turn the shaft carrying the brake shoe to a point at which the brake shoe no longer contacts the core and hence the yarn is free to unwind, whereby when the packages carry elastic yarn it is first stretched by the locked packages as and after clamping to the first carrier, then raised to unlock the packge and permit yarn to unwind freely, whereby the yarn first unwinds to the point where it takes up the stretch and means adjacent the second endless carrier to again lock the package core from turning, the device being provided with a cutting means beyond the second endless carrier for sufficient distance to permit relaxation of the slightly stretched yarn to form a tail of predetermined length.

3. A device according to claim 2 in which the carrier for the packages rotates in a vertical plane, the packages extend horizontally, and the means for raising lowering the packages are cam means attached to the knitting machine frame.

4. A device according to claim 1 in which the intermittent tensioning or gripping means for the yarn are a pair of discs spring urged against each other and a rod pressure on the yarn.

Claims

4. A device according to claim 1 in which the intermittent tensioning or gripping means for the yarn are a pair of discs spring urged against each other and a rod with a wedge-shaped end and cam means attached to the knitting machine frame to move the rod up and cause the wedge to move the disc apart thus relieving pressure on the yarn.

5. A device according to claim 2 in which the intermittent tensioning or gripping means for the yarn are a pair of discs spring urged against each other and a rod with a wedge-shaped end and a cam means attached to the knitting machine frame to move the rod up and cause the wedge to move the discs apart thus relieving pressure on the yarn.