US2949757A

US2949757A - Knitting machine magnetic controlled yarn tension

Info

Publication number: US2949757A
Application number: US743722A
Authority: US
Inventors: Frank R Page
Original assignee: Scott and Williams Inc
Current assignee: Scott and Williams Inc
Priority date: 1958-06-23
Filing date: 1958-06-23
Publication date: 1960-08-23
Anticipated expiration: 1977-08-23
Also published as: GB862149A; DE1215294B

Description

Aug. 23, 1960 I PAGE 2,949,757

KNITTING MACHINE MAGNETIC CONTROLLED YARN TENSION Filed June 23, 1958 2 Sheets-Sheet 1 g3 62 l ull ll;

mlgl lgl I F/G. 5 i'ilhi /m/e/7/0r Fran/r R Page 7 By Ms attorneys 1960 F. R. PAGE 2,949,757

KNITTING MACHINE MAGNETIC CONTROLLED YARN TENSION Filed June 23, 1958 2 Sheets-Sheet 2 mvenfor Fran/r R. Page By Ms af/ameys WWW United States Patentoffice Patented Aug. 23, 1960.

KNITTING MACHINE MAGNETIC CONTROLLED YARN TENSION Filed June '23, 1958, Ser. No. 743,722

9 Claims. (Cl. 66146) This invention relates to magnetic controlled yarn tension for knitting machines and more particularly to the obtaining of accurately controlled tension in' a knitting machineiwhere a very light tension is necessary for normal knitting. In the production of hosiery and other knitted fabric, particularly where the knitting of fine yarns off-nylon, rayon, silk or similar materials is involved, a uniform and usually very light tension on the running yarn is highly desirable. One of the difiiculties in feeding yarn under uniform tension is to prevent any irregularities in initial tension created by any irregu-' larities inoriginal winding of the yarn on the supply package or cone, from being transmitted to the point of knitting. In order to offset these variations in the tension on the yarn as it leaves the tensioning means, it isnecessary that the tensioning means provide offsetting variations which are extremely sensitive and rapid and at the same time accurate. Devices with this object in View have heretofore been known but their operation has generally been dependent on control established by springs and the devices havenot always given satisfactory results. It is particularly difficult to produce even tensioning at the yarn finger when using fine yarns of nylon, rayon, etc., because a very light tension on the running yarn is needed. I found that where the tensioning means involves the use of the phenomenon known as gravity, it is difiicult to produce a light even tension. One'object of the present invention is to provide a form of means which is adapted to produce accurate, even yarn tension in accordance with the needs of the machine when the normal running yarn tension is light It is characteristic of devices made in accordance' with the invention that magnetic repulsion is used to control the light tension under which the yarn is normally knit A comb tension is employed.

In knitting a fine yarn under minimum tension, which yarni must periodically be automatically exchanged. for another similar yarn, there is the problem of preventing a bow inthe yarn which might cause it to bridge the needles as its feed finger drops into action. This fault is usually due to more yarn being drawn from the supply than is required to extend in a straight line from the clamp, to the finger to permit proper seizure by the passingneedles. If this how occurs, the fabric will drop fronrthe needles when the previously fed yarn is removed from action and to eliminate such a possibility it is necessaryto retain excessive tension on the yarn being introduced until it has been seized by the needles. Immediately thereafter the tension must be instantly reduced or cutting in the fabric may result. Magnetic attraction is employed to produce the excess tension and avoidbows in theyarn. This excess tension is released by movement of the yarn itself.

The invention will be shown and described as applied to a circular stocking knitting machine such as referred to in the US. patent to Robert W. Scott, Nos 1,282,958, in whichmachineis'found a circle of independent latch needles mounted in a revolving needle cylinder with pivoted yarn fingers to supply the yarn. It should be understood, however, that the invention is applicable to any kniting machine adapted to use or interchange relatively fine or light yarn.

In the drawings Fig. 1 is a simplified view, partly in perspective and partly in elevation, of certain parts of a circular knit? ting machine containing the invention, the comb tension being turned to appear in side elevation and the parts being shown in their position while feeding yarn to the needles under the balanced light magnetic normal knitting tension.

Fig. 2 is a plan view of the comb tension of Fig. 1.

Fig. 3 is a view in end elevation of the comb tension of Figs. 1 and 2 showing, in the lower part, the two magnets adapted to repulse each other.

Fig. 4 is a diagram showing repulsion between the two lower magnets of Fig. 3 when they are near enough to affect each other.

Fig. 5 is a diagram similar to Fig. 4, showing the magnets so far apart that there is no repulsing action between them.

Fig. 6 is a view similar to Fig. 1 in which the yarn, out of action, is under excess or holding tension to give the delayed excess yarn tension release for a yarn being introduced.

Fig. 7 is a view in vertical section through the comb tension of Fig. 6 taken on the line 77 of that figure showing the magnetic structure used in producing the delayed tension release of Fig. 6, I

, Fig. 8 is a perspective view from the top of the comb tension of Figs. 1 to 7 with the yarn omitted but with the pivoted comb in its upper position as in Figs. 6 and 7.

In the drawings the latch needles N in the needle cylinder 260 are shown passing the throat plate 560. The

yarn fingers

6, 7 are pivoted as usual on a horizontal bar 12, and when down in operating position, feed yam at the throat plate to the needles. Two yarn fingers are shown in the drawings. The normal heel yarn is marked with the letter X and the yarn to be introduced when coming out of the heel is marked with the letter Y.- The yarn fingers are normally tensioned or urged into action by tension springs 14 attached between the upper ends of the fingers and to any stationary part-of the machine- The fingers are raised to non-feeding position by the usual thrust bars 16 through cams on the usual main pattern drum (not shown).

As already mentioned, when knitting a line yarn under minimum tension, which must periodically be automatically eXchan-gedfor another similar yarn, one of the problems which arises is the prevention of a bow forming in the yarn when the yarn finger is brought down into action. Such a how sometimes bridges the needles as the finger drops into action. This fault is usually due to more yarn being drawn from the yarn supply than is required; to extend in a straight line from the yarn clamp holding the idle yarn to the finger so that the yarn may be properly seize-d by the needles. There is a plate 10 inside the needle circle on which is mounted a spring clamp 8 to hold idle yarns. Thus in Fig. 6 the yarn Y which is tobe fed to the needles after knitting the heel has its free endv held under the clamp 8.. I

If such a bow forms, the yarn is not properly ted and the fabric may be dropped from the needles when: the previously fed yarn-is} removed from action. To elimi-j nate the possibility of such a bow forming, it is necess sary to retain excessive tension on the yarnbeing intro? duced until the yarn has been seized-by menswea- 1 However, it isnecessary to reduce the t'ens idii instalrifl'y thereafter to avoid cutting in the fabric. To overcome these difiiculties I provide a delayed tension release or breakaway pull. The desired breakaway pull is obtained by means which I will describe hereinafter.

II My invention will be described embodied in a machine having a so-called comb tension, The comb tension shown can be mounted on any desired part of the machine but in the illustration of the invention shown in the drawings, it is shown attached at a point 42 (see Fig. 2) well above the knitting point. At this point there is a bracket 24 attached to the machine by means of a clamp screw 4-4. While I have shown the comb tension attached in a horizontal position, it may, for convenience, be mounted with the left end lower than the right without interfering with its operation. The bracket 24 acts as a stationary comb or frame mounted on a horizontal axis. It is preferably made of non-magnetic material such as brass or aluminum. Underneath the bracket 24 is a pivoted comb or eye frame 22 which acts as a pivoted guide arm. The frame 22 has extending laterally from it three

eye arms

28, 28' and 28" located near the endsand the middle of the pivoted frame 22, respectively. These eye arms act as pivoted comb teeth in the comb tension, Located between the eye arms are two friction knobs or porcelains fixedly mounted on the fixed bracket 24 by screws 21. They are preferably made of an extremely hard ceramic material such, for instance, as the well known material used for this purpose known as Alsimag. On the end of each

eye arm

28, 28' and 28" is a porcelain eyelet 18 through which the yarn is adapted to be threaded. The yarn also passes under each friction knob 20. It will be seen from Figs. 1 and 6 that when the eye frame 22 and the eyelets 18 are in their uppermost position, the yarn follows a crooked or interlaced path through the comb tension, thereby causing drag on the yarn which provides the excess or holding tension needed in connection with the yarn change above referred to. The eye frame 22 is pivotally carried in the fixed bracket 24 by centers 26 at each end of the eye frame. These centers 26 are clamped in their proper position by screws 27 vertically mounted on either end of the bracket. In order to prevent magnetic leakage the'eye frame 22 may be made of non-magnetic material such as brass or aluminum.

In the drawings I have shown a lug made of iron or other metal subject to magnetic attraction attached to the center eye frame 28'. Located above this lug 30 is an extension 32 of the fixed bracket 24. Located directly above the lug 30 in this extension is an axially adjustable delay magnet 34 held by a set screw 36. Also mounted in the extension 32 is an adjustable stop screw 38 facing downwardly into the path of the eye arm 28'. This stop screw 38 may be locked in any desired position by a horizontal set screw 40 in the bracket extension 32. The adjustable stop screw 38 is adapted to be set to limit the upward movement of the eye frame 22 by having the lower end of the stop screw 38 meet the eye arm 28' as shown in Fig. 7 of the drawings. It might be noted that the are through which the eye frame 22 moves is such that the lug 30 does not actually come in contact with the magnet 34 above it even in the uppermost position of the eye arm 28' shown in Fig. 7. Thus it will be noted that the eye frame 22 can be held in its uppermost position by magnetic attraction between the lug 30 and the magnet 34 but not by actual contact therebetween.

Thus the eye frame or pivoted guide arm can be held up against gravity but I found it desirable to raise it to this position of Fig. 7 mechanically rather than by magnetic means. This upper or delay magnet 34 will attract and hold the eye frame 22 in its uppermost position after the eye frame has been raised mechanically. To do this mechanical raising, I provide the following mechanism. Pivotally attached to the thrust bar 16 underly-' ing the finger 6 carrying the yarn Y is a rod 46. This pivotal connection can be seen in Figs. 1 and 6 at a point 48 substantially opposite the throat plate where the bent end of the rod is located in the thrust rod. This rod 46 is bent upwardly at an intermediate point and is slidably guided in the machine frame by a small guide plate 50 where the bracket 24 is mounted on the machine frame as above described. Below the plate 50' a small connecting link 52 attaches the rod 46 and a vertical rod 54 extending upwardly and parallel to the main rod 46. The upper end 56 of this rod 54 is bent horizontally so as to underlie the eye arm 28". When the short rod Y 54 is pushed upwardly by the raising of the thrust bar 16 to the position shown in Fig. 6, the eye frame 22 is pivoted upwardly until the eye arm 28' rests against the stop screw 38 on the extension 32 of the bracket 24. Thus the raising of the yarn finger 6 to inactivity serves also to swing the eye frame 22 to its uppermost position shown in Figs. 6 and 7. Here the lug 30 being attracted by the delay magnet 34 will hold the

eye arms

28, 28' and 28" in their uppermost position, creating the excess 01' holding tension shown in Fig. 6 due to the increase in the yarn interlace.

In my device not only is magnetic attraction employed for the purpose of applying excess tension which is released by movement of the yarn itself, but I also employ magnetic repulsion acting opposite to the effect of gravity to control the light tension under which the running yarn is held while knitting. In connection with this aspectof my invention, attention is now directed to Figs. 1 to 4 and 7, 8 of the drawings. On the end of the eye frame 22 opposite to that where the bracket 24 for the'comb tension is mounted, there is provided what may be termed as adjustable lower magnet arm 64. On this arm is carried a permanent or lower repulsion magnet 70 whose vertical elevation, with relation to the arm, can be varied by means of a set screw 72 shown in Fig. 3. The fixed angle of the arm 64 with relation to the bracket 24 can be adjusted by pivoting same about the centers 26 in the eye frame 22 within the limits of an arcuate slot 66 in the arm 64. When the proper position has been determined, the arm can be clamped with relation to the centers '26 by means of a clamp screw 68 shown in Fig. 3. The lower pole magnet 70 just referred to is mounted with its south pole at the top and in approximate axial alignment with a pivoted eye magnet 62. This magnet 62 is mounted on the end eye arm 28 by means of a clamp 58 and screw 60 with its south pole facing toward the upper end of the lower or fixed repulsion magnet 70 previously referred to. Since like magnetic poles tend to repel one another when the

magnets

62 and 70 come close enough to have their fields meet, as shown in Fig. 4, magnetic repulsion occurs, tending to swing the eye frame 22 with its eyes 18 upwardly. However, as the two magnets separate, the repulsive force tends to diminish until the fields have no effect on each other as shown in Fig. 5. The parts are so spaced that the repulsion effect between

magnets

62 and 70 shown in Fig. 4 ceases as shown in Fig. 5 before the lug 30 on the eye arm 28' comes within the range of attraction of the magnetic field of delay magnet 34 associated with the fixed bracket 24. In this way the power of attraction between magnet 34 and lugs 30, and the repulsion between

magnets

62 and 70 can never be in action at the same time.

The construction of the mechanism having been set:

forth, sufficient of the operation will now be described to enable comprehension of the manner in which the invention operates. Let us assume that the machine is knitting in the heel using the yarn X as shown in Fig. 6. The yarn Y is threaded through the eyes 18 and around the undersides of the knobs 20 and goes from there in straight lines through any subsequent yarn guides and the yarn finger 6 to the clamp 8. This interlace is shown in Fig. 6. The yarn Y in yarn finger 6 has been raised but of action by the thrust bar 16 as shown in the uppc'r'part of the figure. If the knitting machine attempts to draw on yarn Y, the latter will be subjected to' the predetermined breakaway or excess pull. If desired, the yarn X can be made to pass through another comb tension in which case that second comb tension will be substantially in the position of the comb tension shown in Fig. 1. When, at the end of the heel the yarn finger 6 is to be swung into action, the thrust bar 16 drops down and the yarn Y is lowered to the needles N. The dropping of the thrust bar 16 lowers the upper end 56 of rod 54 out of contact with eye arm 28" but the magnetic attraction between lug 30 and magnet 34 keeps the eye frame up and the tension on the yarn. Because the yarn Y is thus taut, it enters cleanly between two of the needles and yarn demand is established. As this begins to accelerate, there is sufiicient downward pull set up on the eye frame 22 to overcome the attraction of magnet 34 and lug 30 and thus to give the desired breakaway pull. The eye frame 22 instantly drops down to the position of Fig. l where only the light tension is provided on yarn Y by the action of

magnets

62 and 70.

As shown in Figs. 1 and 3, the

magnets

62 and 70 are repelling each other by their opposed south poles to push the eyes 18 up and create some tension around the knobs 20. At times, which may be only momentary in duration, slight additional power is required to unwind the yarn from its supply package and when this occurs, Without some means of compensation, relatively shorter loops have heretofore been drawn by the needles resulting in tight groups of stitches or bands of tight courses depending on the time the yarn is under excess tension. According to my invention, it has been found that by replacing spring or other operating means with the magnetic repelling force, a soft resilient, cushioned, quick recovering action is provided. Thus a slight increase in the power required to unwind the yarn from its package will be instantly detected by the frame 22. As the eyes 18 are lowered by the attempted straightening of the yarn, the yarn has less surface contact with the fixed friction knobs 20, resulting in a lowering of the tension created by the comb tension. This offsets the increase originating at the package and evening that received by the needles. When the tension on the yarn supply lowers, the magnetic repulsion between

magnets

62 and 70 instantly raises the pivoted eye frame and thus continues uniformly the net tension at the needles. By adjusting the lower magnet varying degrees of tension may be applied to the running yarn and the action is much smoother than can be secured from a tension spring.

It will also be seen that the comb can be so built as not to be attested by gravity. In this case the normal pull of the yarn would be against the repelling force of the opposed magnets 62 and 70'.

What is claimed is:

l. A knitting machine yarn tension comprising a comb tension device having relatively movable elements between which the yarn is interlaced and so mounted that gravity tends to reduce the interlace and therefore the tension on the yarn, the device being such that when a yarn is demanded by a knitting machine the interlace tends to allow the yarn to straighten and the tension to be reduced, in combination with repulsion magnetic means associated with the comb tension device in opposition to gravity in such manner that as the yarn tension due to the interlace increases the effectiveness of the repulsion means in opposition to gravity decreases; whereby the yarn is held delicately suspended against gravity.

2.. A knitting machine yarn tension according to claim 1 in which the repulsion magnetic means comprises one or more pairs of magnets with like poles facing each other, one pole being movable with the comb teeth; whereby a repelling force to gravity is provided to help produce the light tension under which the yarn is knit.

3. A knitting machine yarn tension comprising a comb tension device having relatively moving elements between which the yarn is interlaced to provide adjustable tension according to the degree of the interlace, some of said movable elements being subject to the pull of gravity which tends to reduce the tension, in combination-with a magnetic means effective only at the highest tension position of the movable elements to hold the yarn with a predetermined breakaway pull, said position being beyond the normal tension range, and a second magnetic means working in opposition to the pull of gravity eifective in the normal tension range.

4. A knitting machine yarn tension comprising a comb tension device having relatively movable comb teeth and knobs between which the yarn is interlaced to provide adjustable tension, the teeth and knobs being so mounted that when the elements of the device are moved by gravity to more nearly straighten out the interlace the tension on the yarn in reduced, in combination with magnetic means effective only near the highest tension position of the device to give the device a predetermined breakaway pull when the yarn is being introduced to the needles; and a repulsion magnetic means in the device working in opposition to the pull of gravity on the device but effective only in the range below the breakaway position.

5. A knitting machine yarn tension according to claim 3 in which the second magnetic means contain magnetic poles opposing each other; whereby these means are of decreasing efiectiveness as the yarn tension, due to the degree of interlace, increases.

6. A knitting machine yarn tension comprising a comb tension device having relatively movable comb teeth and knobs between which the yarn is interlaced to provide adjustable tension according to the degree of interlace, some of said elements in the device being movable by the pull of gravity which tends to reduce the tension, at repulsion magnetic means associated with the said ele ments which are subject to the pull of gravity but working in opposition thereto and effective only in the normal working range of the device, the comb device being so mounted that when the teeth are lowered by the force of gravity, the tension on the yarn is reduced, in combination with magnetic attraction means tending to hold the teeth lightly in their uppermost position above the normal working range of the device and not affecting their lower positions; whereby when the yarn is being initially called for by the knitting machine from idle position there is a momentary delay in its release by the magnetic attraction means, the yarn being introduced to the needles thereby being given a momentary excess tension with a predetermined breakaway pull, and the yarn is properly fed to the first few needles.

7. A knitting machine, independent knitting needles, a yarn supply, a yarn finger to feed the yarn to the needles, a comb tension device between the supply and the finger; there being in said comb tension device a fixed frame and a pivoted frame, magnetic means on said two frames adapted to be attracted together when the comb tension device is in a position to feed yarn only with excess tension; whereby a yarn being introduced to the needles can be given a momentary excess tension with a predetermined breakaway pull which releases the yarn tension from the force of said magnetic attraction in combination with magnetic normal tensioning means in the comb tension device adapted to provide tension on the yarn when the latter is released from the excess tension.

8. A knitting machine yarn tension comprising a comb tension device having pivoted comb teeth and knobs between which a yarn is interlaced to provide tension adjustable according to the degree of interlace, the teeth being responsive to the pull of gravity which latter tends to reduce the tension, a repulsion magnetic means associated with said teeth but working in opposition to the pull of gravity and effective only below the highest tension position of the device, in combination with an attracting magnetic means elfective only near the highest tension position of the teeth to give the yarn a predetermined breakaway pull when the yarn is being introduced to the needles.

9. A knitting machine yarn tension according to claim 8 in which there is a pivoted yarn finger and mechanical means effective by movement of said finger out of action to place the teeth in their highest tension position where the attracting magnetic means are positioned to give the breakaway pull on the yarn.

References Cited in the file of this patent UNITED STATES PATENTS Raymond Apr. 28, 194-2 Berg July 28, 1959