EP0503216B1 - Needle selection device for circular knitting machine, specially for stockings - Google Patents

Description

The present invention relates to a method and a device for selecting needles for a circular knitting machine, in particular for the manufacture of stockings.

It is known that in circular knitting machines, one or more groups of selections are used, arranged around the cylinder of the needles before each feeding or falling, each group consisting of an electromagnet of maximum width equal to the pitch of the needles and interposed between two permanent magnets, and a pressure cam arranged in correspondence with the magnet which is located upstream of said electromagnet in the direction of movement of the cylinder and which has the function of pushing against the latter an oscillating selector which is housed in a corresponding groove of the cylinder and which is associated with a pusher jack. Notoriously, said electromagnet is controlled by pulses, according to an electronic program synchronized with the movement of the cylinder of the needles, by means of the passage, interruption or reversal of the direction of the current, to allow the permanent magnets to selectively attract the selector. oscillating and avoid the heel of the pusher jack from engaging a control cam and determining the deactivation of the needle corresponding, or by decreasing its magnetic field, to allow them to repel said oscillating selector by causing the lifting of the heel of the pusher jack by this same control cam and the putting into service of the corresponding needle.

It is known from EP-A-0 379 745 that in the attempt to overcome the speed and finesse limitations imposed today, it has been proposed to replace the selector jack oscillating in the vertical groove of the needle cylinder with a jack elastic selector disposed horizontally in a corresponding radial groove in a horizontal crown fixed around the needle cylinder and placing the electromagnet and the corresponding permanent magnets near the head of the horizontal selector jack, which is brought into contact with the magnet permanent matching by the foot of the same pusher jack.
However, this known system still presents the problems associated with the selection of selector jacks by means of a very small electromagnet and these problems increase with the increase in the speed of the cylinder and the fineness of the needles, due to the precariousness of the balance of the forces at play and the difficult-to-assess variation of the different factors such as friction, residual magnetism, induced magnetism, elastic forces which vary due to differences in heat treatments, dimensions or folding of the different rooms. As a result, and by way of example, in a circular machine with 400 needles, the theoretical balance between the weight of a selector jack and the force of attraction which can be obtained with an electromagnet is achieved for speeds not higher than 500 rpm, that is to say incompatible with the speeds, finesse and reliability demanded today by the industry which uses circular machines for socks, in particular for hosiery.

The object of the present invention is to eliminate the aforementioned drawbacks and limitations and to provide a safe and reliable actuation device for elastic horizontal selector jacks, even of very small dimensions, by allowing selection needle by needle, even for finesse. and very high speeds, as is necessary for the manufacture of stockings.

• un anneau magnétisé de manière permanente, fixé à la couronne des sélecteurs élastiques horizontaux à une distance telle qu'il n'agisse pas sur ces derniers lorsqu'ils se trouvent dans la position de repos et, respectivement, qu'il les retienne lorsque qu'ils se trouvent en position active, c'est-à-dire en phase de sélection des aiguilles; et pour chaque position de sélection:
• un aimant permanent, fixé à une partie fixe de la machine en correspondance de la came de pression des jacks pousseurs, immédiatement avant la position de sélection, avec pour fonction d'incliner vers le bas les jacks sélecteurs, en phase de sélection, de la position horizontale de repos, vers et jusqu'audit anneau de retenue;
• un poussoir vertical, positionné entre l'aimant de déplacement des jacks sélecteurs et la zone active de la came de soulèvement des jacks pousseurs et monté sur des moyens de déplacement vertical qui sont commandés de manière à imprimer ou non au poussoir un mouvement vibratoire vertical dont l'amplitude est suffisante pour, respectivement, de décoller ou non les jacks sélecteurs dudit anneau de retenue et ainsi de permettre de ne pas activer ou respectivement d'activer le jack pousseur correspondant juste après le passage de son talon inférieur devant la came de pression.

This result was achieved in accordance with the invention with a circular knitting machine comprising push jacks housed in the vertical grooves of the needle cylinder, horizontal elastic selector jacks, housed in corresponding radial grooves of a circular crown made of material non-magnetic, fixed around the needle cylinder, and having its head which projects into the corresponding groove of the needle cylinder, by equipping said machine with a device for selecting needle by needle composed of:

• a permanently magnetized ring, fixed to the crown of the horizontal elastic selectors at a distance such that it does not act on the latter when they are in the rest position and, respectively, that it retains them when qu 'they are in the active position, that is to say in the needle selection phase; and for each selection position:
• a permanent magnet, fixed to a fixed part of the machine in correspondence with the pressure cam of the pusher jacks, immediately before the selection position, with the function of tilting down the selector jacks, during the selection phase, of the horizontal rest position, towards and up to said retaining ring;
• a vertical pusher, positioned between the displacement magnet of the selector jacks and the active area of the lifting cam of the pusher jacks and mounted on vertical displacement means which are controlled so as to impart or not to the pusher a vertical vibratory movement of which the amplitude is sufficient for, respectively, to take off or not the selector jacks of said retaining ring and thus to allow not to activate or respectively to activate the corresponding pusher jack just after the passage of its lower heel in front of the pressure cam .

Advantageously, said retaining ring for the selector jacks consists of a magnetic ring interposed between two rings, which constitute the pole pieces and are profiled so as to concentrate the flow lines in a short distance.
Said permanent magnet for elastic bending of the selector jacks towards the retaining ring is advantageously positioned astride said retaining ring and with the pole pieces slightly set back relative to those of the retaining ring to prevent contact and therefore the friction of the selector jacks.

According to a preferred embodiment, the means for actuating said pusher consist of a coil which is held in position, elastically, inside a magnetic field generated by a permanent magnet and which is supplied with current. modulated to transmit to the pusher an appropriate vibratory movement, of predetermined amplitude, frequency and phase.

The advantages obtained thanks to the present invention essentially consist in the fact that it is possible to use very light selector jacks, to drastically reduce friction, since the retaining ring of the selector jacks is integral with the cylinder needles and the duration of contact between the selector jacks and the lift-off plunger is reduced to a minimum; that it is possible to keep all the needles in the working position without no selection; that it is possible to operate with electronic control and thus with reliability and security, at higher speeds and finer points compared to those achieved so far; that the device according to the invention is easily and simply adaptable even on circular machines of the reciprocating type, that is to say with double selection or of the type with three-position needles or with a vertical offset of the upper heel pusher jacks.

These advantages and characteristics of the invention as well as others will be more and better understood by each person skilled in the art in the light of the description which will follow and with the aid of the appended drawings given by way of practical example of the invention, but not to be considered in the limiting sense; drawings in which: FIG. 1 shows a developed view of the cam coat with the various selection elements for a circular machine, in accordance with the invention; FIG. 2 shows the sectional view along line AA of FIG. 1; FIG. 3 shows the sectional view along line BB of FIG. 1; FIG. 4 shows the sectional view along the line CC of FIG. 1; FIG. 5 shows the detailed view of the pusher for deactivating the selector jacks of the machine of FIG. 1 with a selector jack in the retaining phase; and FIG. 6 shows the detailed view of the means for retaining the selector jacks of the machine of FIG. 1.

Referring to the Figures of the accompanying drawings, a device for selecting needles, in accordance with the invention, for a circular knitting machine, in particular for the manufacture of stockings, comprising a vertical cylinder 1 with the needles 2 housed in corresponding grooves 3 of the outer wall of the cylinder 1 and the pusher jacks 4, located below, housed and sliding vertically in the grooves 3 of the cylinder, and, moreover, oscillating elastically in the radial direction relative to the cylinder 1 between two positions, a for selection and the other for disabling the needles, depending on which the back of the pusher jacks 4 is respectively raised or adherent to the bottom of the groove 3 of the cylinder 1: each pusher jack being provided with two heels 7,8 directed outwards, an upper 7 cooperating with a cam 9 for lowering the needle position in service to that of selection, the other lower 8 cooper ant with a first cam 10 of centripetal pressure for pushing against the bottom of the groove 3 before each selection group, and with a second cam 11 for lifting to put the corresponding needle 2 in the working position; with the horizontal elastic selector jacks 12, housed in corresponding radial grooves 13 provided in the lower base of a horizontal crown 14, made of non-magnetic material and fixed to the cylinder of the needles, and aligned with those 3 of cylinder 1: each jack horizontal 12 having its foot 16 bent at a right angle and locked against the shoulder of the crown by means of a ring 17 of non-magnetic material and so that in the rest position, it has its back in contact with the bottom of the groove 13 and its head 18 which projects into the corresponding groove 3 of the cylinder 1 of the needles 2.

• un anneau 20 magnétisé de manière permanente, fixé à ladite couronne 14 dans une position au-dessous des jacks sélecteurs 12 horizontaux, à proximité de leur tête 18, et dont la distance verticale est telle qu'il n'agisse pas sur ceux-ci lorsqu'ils sont en position de repos, c'est-à-dire avec le dos en contact avec le fond des rainures correspondantes, et respectivement pour obtenir leur déformation élastique avec pliage vers le bas et leur retenue.

The selection device proper, in accordance with the invention, comprises:

• a permanently magnetized ring 20 fixed to said crown 14 in a position below the horizontal selector jacks 12, close to their head 18, and the vertical distance of which is such that it does not act on them when in the rest position, that is to say with the back in contact with the bottom of the corresponding grooves, and respectively to obtain their elastic deformation with folding down and their retention.

• un aimant permanent 25, fixé à une partie fixe de la machine en correspondance de la came de pression 10 et immédiatement avant la position de sélection, qui exerce un champ d'attraction de puissance et d'amplitude angulaire suffisantes pour éloigner, c'est-à-dire plier vers le bas, les jacks sélecteurs 12 de la position de repos jusqu'à celle de retenue par ledit anneau de retenue 20. Avantageusement, ledit aimant permanent 25 a ses pièces polaires disposées à cheval sur ledit anneau de retenue 20 et avec les extrémités libres se trouvant dans un plan légèrement en retrait, c'est-à-dire plus bas, par rapport à celui des pièces polaires de l'anneau de retenue 20 de manière à attirer les jacks sélecteurs 12 sans qu'ils viennent en contact et donc en évitant toute résistance par frottement de glissement;
• un poussoir 30 sortant d'une plaque 30' fixée à l'extrémité d'une bobine annulaire 31 qui est mobile axialement et élastiquement sur un aimant permanent 32 supporté, à son tour, par une partie fixe de la machine, entre l'aimant d'éloignement 25 et la rampe de la came de soulèvement 11: l'extrémité libre dudit poussoir 30 se trouvant juste au-dessous du plan des jacks sélecteurs 12 et à l'extérieur (en direction centrifuge par rapport au cylindre 1) de l'aimant d'attraction 25, de sorte qu'en alimentant ladite bobine 31 avec un courant modulé, le poussoir 30 est soumis à un mouvement oscillatoire vertical qui est fonction du courant modulé d'alimentation de la bobine. De cette manière, la course vers le haut du poussoir peut être réglée de manière à décoller ou non les jacks sélecteurs 12 qui sont retenus par ledit anneau de retenue 20 et ainsi à maintenir ou à modifier la position de sélection des jacks pousseurs 4 correspondants à leur passage sur la came de pression 10.

Advantageously, this ring 20 for retaining the selector jacks 12 is interposed between two concentric circular rings 21 made of magnetizable material and the upper faces of which constitute its pole pieces are profiled so as to concentrate the flow lines in a short distance;

• a permanent magnet 25, fixed to a fixed part of the machine in correspondence with the pressure cam 10 and immediately before the selection position, which exerts a field of attraction of power and of sufficient angular amplitude to distance, that is to say fold down, the selector jacks 12 from the rest position to that of retention by said retaining ring 20. Advantageously, said permanent magnet 25 has its pole pieces arranged astride said retaining ring 20 and with the free ends lying in a plane slightly recessed, that is to say lower, relative to that of the pole pieces of retaining ring 20 of so as to attract the selector jacks 12 without them coming into contact and therefore avoiding any resistance by sliding friction;
• a pusher 30 emerging from a plate 30 'fixed to the end of an annular coil 31 which is axially and elastically movable on a permanent magnet 32 supported, in turn, by a fixed part of the machine, between the magnet 25 and the ramp of the lifting cam 11: the free end of said pusher 30 being located just below the plane of the selector jacks 12 and outside (in the centrifugal direction relative to the cylinder 1) of the 'attraction magnet 25, so that by supplying said coil 31 with a modulated current, the pusher 30 is subjected to a vertical oscillatory movement which is a function of the modulated supply current of the coil. In this way, the upward stroke of the pusher can be adjusted so as to take off or not the selector jacks 12 which are retained by said retaining ring 20 and thus to maintain or modify the position of selection of pusher jacks 4 corresponding to their passage on the pressure cam 10.

• (a) pour une aiguille en service: en n'alimentant pas en courant la bobine 31 du poussoir 30. De cette manière le jack sélecteur 12 correspondant reste abaissé car il est retenu par l'anneau de retenue 20 situé au-dessous et le pied 6 du jack pousseur 4 est libre de se placer dans la position de repos, c'est-à-dire avec le dos soulevé du fond de la rainure 3 du cylindre 1 des aiguilles, de sorte que son talon inférieur 8 coopère avec la came de soulèvement 11 et l'aiguille 2 correspondante est mise en position de travail;
• (b) pour une aiguille hors service: en alimentant la bobine 31 du poussoir 30, avec un courant modulé en fréquence et en phase. De cette manière le poussoir 30, en vibrant verticalement, heurte le jack sélecteur 12 correspondant qui, en se décollant de l'anneau de retenue 20, se soulève dans la rainure 13 correspondante de la couronne 14 en revenant dans la position horizontale de repos et sa tête 18 bloque le jack pousseur 4 correspondant contre le fond de la rainure 3 de manière que son talon inférieur 8 passe sans coopérer avec la came de soulèvement 11 et que l'aiguille 2 correspondante reste hors service.

The operation is as follows. While the cylinder 1 of the needles moves in the direction of the arrow F, when each needle 2, with a corresponding pusher jack 4 and a corresponding elastic selector 12, arrives in correspondence with the selection group, the pusher jack 4 is located, depending on the previous selection, in raised or lowered position. In the first case, the needle is in the working position and the selector jack 12 is retained by the retaining ring 20. In the second case, the needle is out of work and the pusher jack 4 is with the back in contact on the bottom of the groove 3, forced by the head of the selector jack 12 which is in the rest position, that is to say raised in the groove 13 of the crown 14. In the first case, the pusher jacks 4 which are raised, in contact with the lowering cam 9, are lowered in the selection position while those which are already lowered thus remain. In the second case, the selector jacks 12 which are raised, when passing over the magnet 25 are attracted downwards and retained by the retaining ring 20, and simultaneously, the pusher jacks 4 which are not still in contact with the bottom of their grooves 3 are pushed against it by the active profile of the pressure cam 10. In conclusion, before each new selection and after each previous selection, all of the pusher jacks 4 are with their backs in contact with the bottom of the corresponding grooves 3 and all of the selector jacks 12 are folded down and retained by the retaining ring 20.
At this stage, the new selection is obtained as follows:

• (a) for a needle in service: by not supplying the coil 31 of the plunger 30 with current. In this way the corresponding selector jack 12 remains lowered because it is retained by the retaining ring 20 situated below and the foot 6 of the pusher jack 4 is free to place itself in the rest position, that is to say with the back raised from the bottom of the groove 3 of the cylinder 1 of the needles, so that its lower heel 8 cooperates with the lifting cam 11 and the corresponding needle 2 is put into the working position;
• (b) for an out-of-service needle: by supplying the coil 31 of the plunger 30, with a current modulated in frequency and in phase. In this way the pusher 30, vibrating vertically, strikes the corresponding selector jack 12 which, by detaching from the retaining ring 20, lifts up in the corresponding groove 13 of the crown 14 while returning to the horizontal position of rest and its head 18 blocks the corresponding pusher jack 4 against the bottom of the groove 3 so that its lower heel 8 passes without cooperating with the lifting cam 11 and that the corresponding needle 2 remains out of service.

Claims (4)

1. Device for selecting the needles of a circular knitting machine, in particular for the hose, and including for each needle (2) of an oscillating pushing jack (4) with two claws, an upper one (7) co-operating with a lowering cam (9) in the selection position, and the other lower one (8) co-operating with a pressure cam (10) in the selection position, in a centripetal position relative to the cylinder and with a raising cam (11) and a horizontal elastic selector jack (12), situated in a radial groove (13) of a horizontal ring (14), made of non-magnetic material, fixed around the needle cylinder (1) and with its foot (16) fixed of the said ring (14) and its head (18) which projects into the groove (3) of the corresponding pusher jack (4) and below the latter's foot (6) in the rest position, characterized by the fact that it includes:

   - a permanent magnet ring (20) fixed below the ring (14) and in front of the selector jacks (12) and spaced so that the latter are only carried over when they are situated in their horizontal rest position, ie: folded downwards;

   - a permanent magnet (25) fixed to the fixed structure of the machine corresponding to each pressure cam (10) and immediately in front of the selection position, to enable one to space the selector jacks (12) from one rest position, ie: to fold them downwards and to the retaining ring (20);

   - a vertical pusher (30) which is mounted on a means of actuation (31-33) with vertical oscillation placed between the spacer magnet (25) and the ramp of the said lifting magnet (11) and in a position below the plane of the selector jacks (12) and at distance such that the latter during the upward movement of the pusher cause the release or not of the selector jacks (12) of the retaining ring (20) and thus enable one to maintain or to modify the position of the corresponding pusher jacks (4) in their passage on the pressure cam (10), which corresponds to the non-working and the working position respectively of the corresponding needles.
2. Device according to Claim 1, characterized by the fact that the said spacing permanent magnet (25) of the selector jacks (12) in their rest position has its pole pieces arranged situated on the said retaining ring (20) and with the free ends in a slightly retracted plane, ie: lower relative to the pole pieces of the retaining ring (20).
3. Device according to Claims 1 and 2, characterized by the fact that the said retaining ring (20) is interposed between two rings (21) made of magnetic material and with the free ends profiled so as to concentrate the flux lines in a small distance.
4. Device according to Claim 3, characterized by the fact that the said means of control of the oscillation of the pusher (30) consist of a bobbin (31) which is maintained in position, in an elastic manner, inside the magnetic field produced by a permanent magnet (32) and which is fed by a modulated current to transmit a vibrating movement of predetermined amplitude, frequency and phase to the pusher.

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