GB2102455A - A yarn feeding apparatus for multi-feed knitting machines - Google Patents

Abstract

Yarn feeding apparatus for multi- feed knitting machines, particularly for circular knitting machines, comprising a rotatable roller or wheel 2, on which a belt 5 operates and presses thereon a yarn 8 passing between eyes carried by a yarn inserting arm 6 and a yarn outlet arm 9, such arms being movable between a position for holding the yarn between the belt and roller or wheel, and a position at which the yarn is thereby held out of contact with the belt. The apparatus comprises an eye 12, positioned between the belt and the outlet arm, which is always laterally displaced relative to the belt, and through which the yarn outletting from the apparatus passes before passing to the outlet arm. Thus, the time required for discontinuing the yarn supply by the apparatus is considerably shortened. <IMAGE>

Description

SPECIFICATION A yarn feeding apparatus for multi-fall knitting machines This invention relates to a yarn feeding apparatus for multi-fall knitting machines, particularly for circular knitting machines.

As well known, in multi-fall knitting machines, that is to say in those machines wherein a knitted fabric is formed through needles drawing a plurality of feeding yarns from a plurality of cops or the like, such yarns are drawn from the cops and fed to the needles through feeding apparatuses, each comprising a roller or wheel freely rotable about its own axis and having a substantially cylindrical shaped surface, on which a yarn can be pressed and held by a belt of lower height than that of the roller or wheel advanced by means of a drive member.

The belt advancement causes the roller or wheel to rotate and draws the yarn from the relative actuation cop, which yarn, when released from the belt and roller or wheel, is thus supplied to the respective needle at predetermined speed.

In case of circular knitting machines, rollers or wheels of this type are arranged according to a circule at the machine top and the belt rotably driving the same is single and loop closed.

The need often occurs to move one or more yarns out of the contact with the belt, displacing the involved yarn in the direction of the roller or wheel axis laterally of said belt. The yarn slips on the surface of the roller or wheel, which continues to be rotably driven by the belt, but with the latter no longer acting on the yarn. This occurs, for example, when the stitch length has to be changed on the knitting machine, or when the type of fabric being produced by the machine has to be changed, or again when a knitted fabric is produced having stripes of different colours and when desiring to leave out one or more yarns of a given colour from the fabric being formed.

Since knitting machines operate at high speed, when the necessity occurs of discontinuing the supply of a given yarn, steps must be taken for high speed removal of the involved yarn from the position at which such a yarn is pressed between the belt and relevant roller or wheel.

Each of the yarn feeding apparatus are provided with a movable outlet arm for the passage thereon of the yarn moving out of the apparatus, and which is responsive to the outlet yarn tension. The loosening of the outlet yarn tension decreases the pressure on said arm, which mechanically or otherwise acts upon a yarn insertion arm or a guiding slit, which it lifted and moves the yarn away out the pressure zone of the belt on the roller or wheel. The movable outlet arm is somewhat longer than the yarn insertion arm, and the yarn passing over the involved roller or wheel passes on two eyes, one integral with each of the two arms. As the yarn is withdrawn, both of the arms are displaced to the belt, so as to hold the yarn under the belt at a position substantially longitudinally of the belt.When the supply of the involved yarn has to be discontinued, the displacement of the two arms draws the yarn out of the contact with the belt and relevant roller or wheel.

Feeding apparatuses of this type are well known and described, for example in the German Patent No. 1 585298 and the published German Patent Application No. DOS 1635893, but have the disadvantage or requiring a relatively extended period of time between the time at which the movable outlet arm acts upon the movable inlet arm shifting the yarn laterally of the belt: such a time is determined by the required time that, following the side displacement of the inlet arm relative to the belt, the whole length of yarn, which is pressed between the belt and roller or wheel in parallel relationship to the belt, is withdrawn away from below the belt.In other words, for withdrawing the yarn away from the zone of contact between the belt and roller or wheel, the latter should rotate through an angle equal to the maximum angle according to which the contact between the belt and roller or wheel would occur.

Additionally, during the yarn feed the outlet arm takes a position that is determined by an .outlet eye integral with such an arm and by a location where the yarn leaves that zone at which it is pressed between the belt and roller or wheel.

As a result, when the outlet arm is moved or driven to control the arrest of the yarn feed, it is pulled towards the belt by the yarn which is substantially at intermediate position to the belt.

This will imply that the movement of the outlet arm is considerably hindered.

Along with the above mentioned factor, this factor means that a relatively extended time is required between the time at which the arrest for the supply of a yarn is given and the time at which such a supply effectively ceases, which makes the apparatus unusable when the yarn insertion and/or disconnection has to be rapidly carried out.

It is the primary object of the present invention to provide an improved yarn feeding apparatus, wherein the time for discontinuing the yarn feed is very short.

It is another object of the invention to provide an apparatus of the above mentioned type, which is of very simple structure and low cost of production.

These and still other objects are achieved by a yarn feeding apparatus for knitting machines comprising a roller or wheel freely rotably mounted on a rigid support which can be secured on a machine and having a plurality of spokes distributed on a cylindrical surface coaxial with said roller or wheel and on a surface arc of which a belt can be seated, the height of this belt being less than the height of said spokes, two rocking arms being mounted on said rigid support and having eyes for the yarn passage, a yarn inlet arm being adjacent to that zone at which said belt comes in contact with said roller or wheel, and a yarn outlet arm being adjacent to that zone at which said belt separates or moves away from said roller or wheel, such arms being rockable between a position, at which the respective eye is moved at the level of said belt, and a position at which said eye is displaced laterally of the belt, characterized in that at that side where the yarn outlet arm is provided, in close proximity to the roller or wheel an outlet eye is provided for the passage therein of the yarn that has passed on the roller or wheel, such an outlet eye being always displaced laterally of said belt at any operating condition of the apparatus.

In order that the structure and features of the yarn feeding apparatus according to the invention be more clearly understood, two embodiments thereof will now be described as given by mere way of unrestrictive example, with reference to the accompanying drawings, in which: Figure 1 is a front elevational view showing an apparatus provided with a fixed outlet eye, the apparatus being shown at operating conditions, when it draws the yarn to be supplied to the needles of the knitting machine; Figure 2 is a view fully similar to that of Figure 1, but showing the apparatus at inoperating conditions, that is at those conditions at which it does not withdraw any yarn and does not supply it to the needles of the knitting machine; Figure 3 is a side elevational view of the apparatus, according to arrow Ill of Figure 1;; Figure 4 is a fragmentary top view of said apparatus, according to arrow IV of Figure 1; Figure 5 is a front elevational view showing a portion of an apparatus similar to that of Figure 1, but provided with a movable outlet eye, also in this case such an apparatus being at the yarn feed conditions; and Figure 6 is a view similar to that of Figure 5, but showing the apparatus as it draws and supplies the yarn.

Referring first to Figures 1 to 4, in which a yarn feeding apparatus for knitting machines is shown as comprising a rigid support or casing 1, on which a roller or wheel 2 is mounted freely rotable about its own axis, the periphery of this roller or wheel 2 being defined by a plurality of metal spokes 3 distributed on a cylindrical surface.

On a short section arc of the cylindrical zone defined by said spokes 3 bears a closed continuous tape belt 5 (Figure 4), the height of which is considerably less than the length of spokes 3, as it will be seen from Figures 1 to 3.

When the roller or wheel 2 is rotating, also the belt 5 rotates without grazing on the roller or wheel.

The apparatus casing 1 has rockably mounted on a horizontal pin (as seen in Figures 1 to 3) a supply or inlet arm 6 having an eye 7 (comprising for example a small ring of ceramic material), in which the yarn 8 from a cop not shown on the drawing or other similar body passes and slides.

The supply or inlet arm 6 is oscillable between two positions of end of stroke, at one of which the eye 7 is at a lower level than the upper edge of the belt 5, and at the other position of which such an eye is displaced laterally of the belt. At the first position (Figure 1) the apparatus is operating, while at the second position it is inoperative or out of service. Additionally, it should be reminded that it is not strictly necessary that at working position the eye 7 is lower than the upper edge of the belt or tape 5, since expedients are also provided, such as fixed or adjustable rods inclined towards the belt, on which the yarn 8 grazes for being moved to a lower level than the upper edge of the belt, even if said eye 7 remains at raised condition relative to said upper edge.Such a structure is per se known and is disclosed both in the German Patent No. 1585298 and in the published German Patent Application No. DOS 1 635893.

Still on said casing 1, an oscillating outlet arm 9 is mounted, also rotable about a horizontal axis with respect to Figures 1 to 3, which arm 9 carries eyes (also usually housing small rings of ceramic material), respectively designated by reference numerals 10 and 1 having passing therein the yarn 8 from the eye 7.

The function of said outlet arm 9 will not be herein further described, because of being per se well known. It will suffice to note that such an arm is retained at lowered position, shown in Figures 1 to 3, by the yarn 8 maintained under tension during its withdrawal by the needles of the knitting machine. When such a tension gets loosened (for example, because the yarn is no longer withdrawn by the relative needles, or just because it is broken), the outlet arm 9 is automatically upward lifted by a spring (not shown) and causes the inlet arm 6 to be lifted from the operative position of Figure 1 to the inoperative position of Figure 2. This is done in order to move the yarn 8 out of the zone of contact between the belt or tape 5 and the surface portion of the spokes 3 on which said belt is pressed, holding and drawing the yarn when it is at lowered position. (Figures 1, 3 or 4).

The structure of the apparatus hitherto described is well known and accordingly no further details are required for showing the operation thereof.

However, it should be pointed out that a problem of outstanding importance is that of allowing the fastest passage of the yarn from the drawing position of Figure 1 to the inoperative position of Figure 2, in order to avoid to continue to draw and supply the yarn to the needles when the latter either do not any longer withdraw yarn, or withdraw yarn in a lower amount.

To this end, according to the invention, a fixed outlet eye 12 is provided on the apparatus and through a small bracket 13 is integral with the apparatus casing 1. As clearly shown in Figures 1 to 4, said eye 1 2 is positioned in close proximity to the roller or wheel and is laterally displaced (that is above, as seen in Figures 1 to 3) relative to the belt 5. As a result, after passing through the eye 7, the yarn 8 passes into the eye 12 before passing into the eyes 10 and 11 of the yarn outlet arm.

Owing to the position of the fixed eye 12, at the operative conditions (Figures 1 and 3) the yarn 8 which is pressed by the belt 5 against the spokes 3, does not have a fully horizontal attitude throughout along the zone of contact of the belt with the adjacent spokes, but said fixed eye 12 acts on the yarn by upwardly withdrawing it (and thus tending to move it out of the contact by said belt 5) also at the zone where the belt is still pressed on the roller or wheel spokes, as clearly shown in Figure 1. First, this causes the fact that the yarn length comprised and pressed between the belt or tape 5 and spokes 3 is less than the length or extension of the circle arc comprising the actual zone of contact of the belt on the spokes.

Moreover, the provision of said fixed eye 12 enables an easier and faster upward rotation of the outlet arm 9 where the yarn outletting from the apparatus should undergo a decrease in tension.

This is caused in that the fixed eye 12 moves to a higher level, that is closer to the pivot pin of the outlet arm 9 the location from which the yarn arrives that is directed to the eyes 10 and 11 of said arm. Thus, in the absence of said fixed eye 12, during the yarn feed, said yarn would be taut between the belt 5 and eye 10, and accordingly larger would be the distance or spacing between the pivot pin of arm 9 and yarn, which would constitute an increased brake against the upward movement of the arm.

Then it results that due to the two above mentioned factors the provision of said eye 12 at the position described with reference to Figures 1 to 4 causes a high increase in sensitivity and reaction speed of the apparatus as the outlet yarn tension varies, and enable to set the yarn out of service much more rapidly than obtainable by similar apparatuses of known type, but without the above described fixed eye 12.

A variant has been shown in Figures 5 and 6, in which the eye 12 of Figures 1 to 4 is replaced by an eye 22 which is integral with an arm 23, the latter being rotatable about a horizontal axis 24 having rotably mounted thereon a sleeve 25, on which the arms 6 and 9 are keyed. The axis 24 and sieeve 25 are interconnected (for simplicity not shown), so that they rotate relative to each other in opposite direction. When said arm 6 rotates, the arm 23 also rotates, but this embodiment is characterized in that said eye 22 remains always laterally displaced both at operating conditions (Figure 5) and mostly at the conditions of out of service, and more particularly above said belt 5, as seen in the drawings.

Therefore, the behaviour and effect of this movable eye 22 are the same as described with reference to the fixed eye 12, since in any case said movable eye 22 will substantially take the position of the fixed eye 1 2 at the operative conditions of the apparatus (Figure 5).

From the foregoing it will be readily understood that the structure of the improved yarn feeding apparatus according to the present invention is extremely simple and that easy are the modifications to be made to the existing similar apparatuses of known type.

Also the utilization of the apparatus does not present any kind of problem, as it is exactly used as the known apparatuses presently on commerce.

Claims (4)

Claims

1. A yarn feeding apparatus for multi-fall knitting machines, comprising a roller or wheel freely rotably mounted on a rigid support that can be secured onto a machine, and having a plurality of spokes distributed on a cylindrical surface coaxial with the roller or wheel and on a surface arc of which a belt can be seated, the height of the belt being less than the height of said spokes, two rocking arms being mounted on said rigid support and having eyes for the yarn passage, a yarn inlet arm being adjacent to that zone at which said belt comes in contact with said roller or wheel, and a yarn outlet arm being adjacent to that zone at which said belt separates or moves away from said roller or wheel, said arms being oscillable between a position where the respective eye is displaced at the level of said belt, and a position where said eye is displaced laterally of said belt, wherein at that side where the yarn outlet arm is provided, in close proximity to the roller or wheel, an outlet eye is provided on which the yarn passes after passing on the roller or wheel, said outlet eye being always displaced laterally of said belt at any operating condition of the apparatus.

2. A yarn feeding apparatus according to Claim 1, wherein said outlet eye is integral with said support for said roller or wheel.

3. A yarn feeding apparatus according to Claim 1, wherein said outlet eye is carried by a movable arm keyed on a rotable axis, to which said yarn inlet arm is also keyed, the outlet eye being displaceable between two positions of end of stroke, at each of which it is positioned laterally and out of said belt.

4. A yarn feeding apparatus as hereinbefore described with reference to and as shown in the accompanying drawings.