GB2177124A - Thread feeding device for circular knitting machine - Google Patents

Abstract

A device for feeding the thread to a circular knitting machine, comprises at least one thread guide 11 borne by a support structure and provided with at least one bore 18, 19 for feeding a respective stitch-forming thread, the thread guide being positioned substantially upstream of the end point of the up stroke of the needles and receives the thread from its radially inner side, to supply it towards the outer side relatively to the imaginary cylindrical surface defined by the circle of needles, the thread guide being moreover positioned in such a radial position that the needles in their up stroke step engage the stretched thread 12 between the hook top and the tip of the needle latch so as to open the latches 3C. The second bore 19 may be used for plating, its thread passing through the bore in an inward direction. A bevel 24 deflects needles in an incorrect raised position. <IMAGE>

Description

SPECIFICATION Thread feeding device for circular knitting machine The present invention relates to a thread feeding deviceforuseonacircularknitting machine.

It is known that the traditional thread guides which provideforthefeeding ofthethread on circular knitting machines comprise generally an eye or bore through which the thread runs towards the needles, coming from the outside ofthe machinetowardsthe inside thereof.

The same thread guides are so positioned that the needles which have been raised to theirthread taking-up position, take up this thread by their hook during their down stroketowards the stitch formation position, the thread being stretched between the last needle which isforming the stitch and the thread guide eye orbore. Duetothisreason,thethread guides are placed in a position of substantial vertical alignment with the needle raising cam, i.e. with the highest position reached by the needles in their up stroke.

This arrangement of the thread feeding hasthe drawback that the thread guides cover the upper portion of the zone of needles reciprocating motion for thethread taking-up, rendering this zone practically inaccessible and the thread taking-up movement by the needles practically invisible.

Furthermore, as the thread guides must be as close as possible to the needle path, they are frequently struck by the not completely open needle latches, which impact against the front side edge of the thread guide, suitably inclined to cause the not completely opened latches to be fully opened, but by so doing a considerable wear ofthe inclined surface ofthe thread guide occurs, with damaging ofthe same surface, which within a short time causes the damaging ofthe needle latches.

If then the latches are not even partially open, but they are still completely closed, they impact against the thread guides, damaging them and being damaged bythem, to the pointthat often it is not even possible to continue operating.

Furthermore, the mutual positioning ofthethread guides and of the needles favours the deposition of lint in the feed areas, with consequent possible improper operation of these components.

The purpose of the present invention is to overcome these problems, providing a thread feeding device for use on a circular knitting machine which, by securing the correct reciprocating motion ofthe needles and the correct th read taking-up by them, does not cause the wearing orthe damaging ofthethread guides and ofthe needle latches, and moreover allows the step of thread taking-up bythe needles to be immediately observed for a possible intervention in case of anomalies.

In view of such a purpose, a device is therefore proposed forfeeding the thread to a circular knitting machine, comprising at least one thread guide borne by a support structure and provided with at least one bore for feeding a respective stitch-forming thread, the thread guide being positioned in correspondence ofthe needle-raising zone ofthe machine,forthe taking-upofthethread bythesameneedles,characte- rized in thatthe thread guide is positioned substantial- ly upstream the end point of the up stroke of the needles and receives the thread from its inner side, to supply ittowards the outer side relatively to the imaginary cylindrical surface defined bv .ne circle of needles, the thread guide being moreover positioned in such a radial position that the needles in their up stroke step interfere with the stretched thread in a point ofthe hook curve being between the hook top and the needle latch.

Afeeding device ofthistype results hence positioned upstream the zone of highest needle raising, thus leaving this zone, as well as the immediately following zone, wherein the needles, in their down stroke step, take up inside their hookthe stitch- forming thread, free for inspection and intervention.

Moreover, the feed ofthe thread from the inside to the outside ofthe thread guide, on considering the imaginary cylinder defined by the circle ofthe needles, and the position of the thread guide relatively to said circle, cause the th read fed to come into such a position as to act it itself, thanks to its tension, as a device opening and not completely opened latches, without that a material contact of the latches with the thread guide,which may deteriorate either of or both ofthese elements, may occur.But also the latches completely closed, and hence apparently unable to secu re the co rrect taking-up of the th read bythe respective needles, are anyway opened by the same th read, which by sliding undertension on the outer curved portion ofthe needle hook, suitably adjusted, runs progressively downwards always remaining in contact with this portion during the up stroke ofthe needles, entering between the closed latches and the tip ofthe needle hooks, and opening the latches at least to an extent allowing the correct taking-up ofthe thread.

The shifting ofthe position ofthethread guide upstream the point of traditional positioning and the feed of the thread in the reverse way relatively to the prior art, allow therefore several advantageous results to be achieved, not only by securing the visibility of and accessilibityto the thread taking-up zone, butalso avoiding the mechanical components to be worn down.

It should be noted that by providing thethread guide with two feed bores, the device becomes also suitable to the manufacturing of plated knitted fabric, as it shall appear more clearly from the following.

For greater detail, the invention is disclosed in the following by referring to a preferred form of practical embodiment, illustrated to exemplifying and not limitative purposes by the attached drawings, wherein: Fig. lisa partial axial section of a feeding device according to the invention on a circular knitting machine in correspondence of a thread feed; Fig. 2 is a view of the device taken from the outside ofthe machine, wherein the pattern ofthe needles stroke in correspondence of the feeding zone is schematicallyshown; Fig. 3 is a partial view ofthe device of Fig. 2, taken along the machine circumferential direction, by view ing from the left hand side of Fig. 2; Fig. 4 is a sectional view taken along the path IV-IV of Fig. 2;; Fig. 5 and Fig. 6 are schematic enlarged-scale views of the step of opening of a latch remaining closed, beforethethreadtaking-up; Fig. 7 is a schematictop view of a portion of the device fitted to the manufacturing of plated knitted fabric.

Referring to the above figures, a feeding device 1 is associated to a circular knitting machine having a revolving cylinder 2, needles 3 sliding inside longitudinal slots 4 of cylinder2, sinkers 5 sliding inside radial slots 6 of a sinkers crown 7, and driven bythe cams 8 of a stationary part 9.

To the stationary part9 in correspondence of a machinethread feed, a structure 10 supporting a thread guide 11 extending in a substantial vertical direction is fastened. The thread 12 comes to the thread guide 11 through a bore 13 provided on a plate 14,fastended atop the structure 10, and preferably provided with a bore 15 at its opposite end, to accommodate a second thread.

Thethread guide 11 can be adjusted in a known way in the peripheral direction relatively to the support block 1 6which bears it, and which is in its turn adjustable in the radial direction ofthe machine, together with thethread guide 11. Forthe adjustment in elevation, spacers 17 are provided.

The thread guide 11 is preferably provided with two bores 18 and '19 for feeding a respectivethread, positioned in its lowermost portion close to the circle of needles 3. These latter are provided in a known way with butts3a,driven bycams20stationary relatively to the cylinder 2.

According to the invention, the thread guide 11, positioned in correspondence ofthe zone of raising of the needles 3, forthe taking-up ofthe thread, is positioned substantially upstream the end top point of the up stroke of the needles 3. The trajectory of the upper end of needles 3 is indicated by the continuous line Sand follows, in a known way, the pattern of the raising cams, not shown in detail. In otherterms,the thread guide 11 is positioned backwards (in the direction of relative motion ofthe needles 3 relatively to the thread guide 11), relatively to the traditional position of a corresponding thread guide, as schema tically shown by the broken line 21.

Such a positioning allows the zone of upwards motion ofthe needles 3, as well as the subsequent zone of down stroke ofthe same needles, to be perfectly visible and accessible.

Always according to the invention, the thread 12 is fed from the inner side outwards, relatively to the imaginary cylindrical surface defined by the circle of needles 3, as it can be seen from thefigu res. This occurrence, together with the relative positioning of the thread guide 11 relativelyto the path ofthe needles 3, causesthethread 12 to be positioned, under well-stretched conditions, in the same trajectory of the needles 3.In particular, itoccursthatthethread 12 runs from a radially outer side towards a radially inner side relatively to the circle ofthe needles 3,that secures a correct possibility oftaking-up ofthe thread 12 by the needles 3 during their down stroke step, as well as, bya correctadjustmentofthethread guide 11 relativelyto thetrajectory ofthe needles 3, the interference ofthe needles 3 with the thread 12 in a point ofthe curve of the hook 3b of the needles 3 between the hooktop andthe latch 3cofneedles3.

Advantageously, this interference allows the open ing to be obtained of not completely opened latches, as well as of completely closed latches, as it can be seen at Figs. 5 and 6. In fact, the stretched thread 12 which, during the up stroke ofthe needles 3 slides on the outer edge of the curved portion of the hook of needles3, moving awayfrom its initially rectilinear trajectory, maintains constantly its contact with the hook 3b and hence automatically enters between the hook3b and the latch 3c, opening iton continuing its movement.

Bythe invention therefore no mechanical contacts occur between the latches and the thread guide, and hence neitherwear of of such parts nor possible damaging or breakage ofthe same parts may occur.

Advantageously, the thread guide 11 can bevertically lined upwith the circle of needles 3, and have a beveling 22 on the downstream side of its lower edge, substantially fitting to the pattern of the up stroke portion of the trajectory S of needles 3, at a short distance from it.

Athread guide 11 having two vertically and horizontally staggered bores 18 and 19, in the nearby ofthe beveled portion 22 is suitable to be used for the manufacturing of plated knitted fabric, with the two threads 12 and 23 being fed from opposite sides, viz.

the one from the inside and the other one from the outside ofthe machine, as Fig. 7 shows. Of course, in this case the thread guide shall be suitably adjusted in radial direction relatively to the machine, in orderto achieve the correct taking-up ofthe two threads 12 and 23 by the needles 3.

In its lowerfront portion, the thread guide 11 can be provided with a beveling 24 so shaped as to cause the radial pushing outwards of needles 3 wrongly running along a high trajectory relatively to the working trajectory, for example because they have their butt 3a broken.

The wide free zone in correspondence on the up and down stroke ofthe needles prevents also lint from accumulating in this zone.

Hereinabove, the case has been disclosed of a circularmachinewith revolving cylinderand cams borne by a stationary structure, but it is understood that the invention is applicable as well to a circular machine with stationary cylinder, and cams borne by a revolving structure.

Claims (9)

1. Device forfeeding the th read to a circular knitting machine, comprising at least one thread guide borne by a support structure and provided with at least one bore for feeding a respective stitch-fo rming thread, the thread guide being positioned in correspondence ofthe needle-raising zone ofthe machine, forthetaking-up ofthethread by the same needles, characterized in that the thread guide is positioned substantially upstream the end point ofthe up stroke ofthe needles and receives the thread from its inner side, to supply it towards the outer side relatively to the imaginary cylindrical surface defined bythe circle of needles, the thread guide being moreover positioned in such a radial position that the needles in their up stroke step interfere with the stretched thread in a pointofthehookcurvebeing between the hooktop and the needle latch.

2. Device according to claim 1, characterized in thatthethread guide is substantially vertically aligned with the circle of needles.

3. Device according to claim 1 or2, characterized in that theth read guide has a beveling in its downstream lower edge, substantiallyfollowing the pattern ofthe needles up stroke trajectory.

4. Device according to claim 1, characterized in thatthethread guide is radially adjustable relatively to the circle of the needles.

5. Device according to claim 1, characterized in that the thread guide is provided with two feed bores mutually vertically and horizontally staggered, in the nearby of a beveled portion substantially fitting to the pattern ofthe up stroke trajectory ofthe needles.

6. Device according to claim 1 and 5, characterized in that the threads fed to the two bores are fed from opposite sides.

7. Device according to claim 1, characterized in that the th read guide is provided with a beveling in its lowerfrontedgeforthe radial expulsion of needles following a high trajectory relatively to the working trajectory.

8. A device forfeeding thread to a circular knitting machine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

9. Acircularknitting machine including a device according to any preceding claim.