EP0343123A2 - Numerically controlled electro-magnetical needle selection device for three positions on circular-knitting machines with alternating movement - Google Patents

Abstract

To make the numerically controlled electromagnetic selection of needles with three positions, that is to say "floating" point, "retaining" point and "cast-off" point, in each of the directions of rotation of the needle cylinder of a circular knitting machine with alternating movement for producing socks with a "marquetry" design, there are used: - a cylinder 1 with needles 2 and keys 4 and with pusher jacks 6 equipped with a heel 7, 8 at the two ends and subject to a rear centrifugal spring 10; - two oscillating selectors 11, 12 superposed vertically and arranged symmetrically relative to the horizontal separating line, each with a convexity towards the corresponding pusher jack 6 and with three outwardly directed heels, two of these 15, 17, corresponding to the ends, being juxtaposed respectively with a pressure cam 25, 26 and with a spacing ring 18, and the third, which is intermediate, forming the anchorage by magnetic attraction; and for each supply: - two electromagnets 21, 22 arranged superposed vertically for the selection of the said oscillating selectors 11, 12, the simultaneous deactivation of which determines the lower position of the needle for the floating point; - a ring 18 for spacing the oscillating selectors 11, 12 in relation to the said electromagnets 21, 22 in the attracted position and rotating in conformity with the needle cylinder; - a cam 31 for controlling the pusher jacks 6 when the lower oscillating selector 11 is deactivated in order to obtain the intermediate position of the needle for the retaining point; - a cam 30 for controlling the keys 4 when the two oscillating selectors 11, 12 are activated, to obtain the upper position of the needle for the cast-off point. <??>With such a selection device, it is possible to reduce the diameter of the needle cylinder to less than 4" with a fineness higher than 120 needles, and to work at a speed higher than that allowed at the present time. <IMAGE>

Description

The present invention relates to an electromagnetic selection device with numerical control of the needles with three positions for meturon circular knitting machine with reciprocating movement, in particular for the manufacture of socks with design of "marquetry" or "mosaic".

It is known that in circular knitting machines, groups of selections are used arranged around the needle cylinder before each feeding or dropping, each group consisting of an electromagnet interposed between two permanent magnets and a pressure cam arranged in correspondence of the magnet, which is located upstream of the electromagnet, in the direction of movement of the cylinder, to push against the latter the oscillating selector associated with an elastic pusher jack.

The electromagnet is controlled, according to an electronic program synchronized with the movement of the cylinder of the needles, by means of a modulated passage, an interruption or a reversal of the direction of the current, for, selectively, maintaining attracted and adhering to the magnets the oscillating selector and avoid the heel of the elastic jack from engaging a control cam and determine the deactivation of the corresponding needle, or release, that is to say push back, the said oscillating selector causing the heel of the elastic jack to be raised by the same control cam and the commissioning of the corresponding needle.

Therefore, for each supply, as many selection groups as there are control cams are required; in the case of three needle selection positions (that is to say for the "floated" point, the "retained" point and the "discharged" point) two selection groups are required for each feed and, for a machine with reciprocating movement, four selection groups are required as described for example in USA patent n. 3,972,206 and in Italy patent application no. 9472-A / 84.

By using so-called "memory" systems, for example electromechanical, it is possible to arrive at a solution with three selection groups, the central one of which cooperates alternately with one of the lateral ones, but as far as sock machines are concerned. small diameter, there are problems of space, reliability and mechanical which make this solution unacceptable. When using electromagnetic selection, the problem arises of pressure cams intended to push the oscillating selector against the magnet which is located upstream of the selection electromagnet for each selection and in both directions of rotation, said cams, if they are fixed, are incompatible with the path of the needles, otherwise they require complex synchronization devices. In addition, the electromagnet must have a maximum width equal to the distance between one needle and the next to be able to act, each time, on a single selector without interfering with those adjacent.

The main problems inherent in known electromagnetic systems are therefore related to the space available and the force of attraction provided by the selection electromagnets. Indeed, the space required to select three needle positions in the two directions of movement of the needle cylinder, for example on a machine with four feeds for men's socks with marquetry design ", is such that it does not allow the use of cylinders with a diameter of less than four inches, when a diameter of 3 3/4 "or even 3 1/2" is required when a fineness greater than 120 needles is required. And the force of attraction or repulsion of the selection electromagnet, being linked to the passage section of the magnetic flux, depends directly on the pitch of the needles as mentioned above, and therefore, in the case of great fineness, it is very low and once reached the saturation level, cannot be further increased, even by increasing the number of turns or current intensity. Insufficient magnetic force makes the balance between the elastic reaction of the selector, the inertia of moving parts, centrifugal force, friction, etc. very precarious, and therefore negatively limits the maximum attainable speed and operating safety. .

To reduce the wear of the magnets, a surface of non-magnetic material has been adopted on which the selection members slide attracted by the magnets, but this exerts a tangential force which pushes the said selection members against the walls of the grooves, increasing thus friction and preventing the free movement of the organs themselves in proportion to the operating speed. Finally, to obtain the elastic reaction of the selector stressed at one end, it is necessary to maintain an embedding pressure at the other end and this sliding reaction is undesirably high taking into account the length of the selector.

The present invention aims to eliminate the aforementioned drawbacks.

This result was achieved in accordance with the invention by adopting the idea of using, for each needle: a pusher jack with two heels, that is to say one for each end, which are pressed, separately, towards the outside of the cylinder, by at least one spring; two corresponding oscillating selectors, superimposed vertically and placed opposite the pusher jack; and, for each power supply: two electromagnets, vertically superimposed for the separate selection of said oscillating selectors, each interposed between two permanent retaining magnets and cooperating with the corresponding oscillating selector pushed against it by a symmetrically shaped pressure cam, to select or not the corresponding heel of the pusher jack; two cams, one lower and the other upper, for lifting the selected corresponding push jacks, in the position of the retained point or the discharged point, respectively.

According to other characteristics of the invention, each oscillating selector oscillates about a median axis to allow that one of its ends cooperates with the pusher jack and with the corresponding pressure cam, and that the other end cooperates with a peripheral ring intended to keep the oscillating selectors attracted by the electromagnet, slightly separated from the magnets and electromagnets, so as to reduce the wear of the magnets and the resistive forces of friction.

The solution proposed by the present invention allows the realization of a circular knitting loom with reciprocating movement, with a cylinder of reduced dimensions, with the electromagnets of selection provided with poles of larger section and therefore with a higher force of attraction and at the same time, using pressure cams with ridges of length less than that of said poles to push the oscillating selectors directly against the electromagnets. This solution also makes it possible to prevent the pusher jacks from being elastic and therefore to suppress the corresponding high elastic reaction forces which are difficult to control and the cantilever type embedding reactions. But above all, we get a circular knitting machine with high operating reliability even at very high speeds, low cost, easy adjustment, control and maintenance, even for the production of socks with a "marquetry" design.

• - la FIG. 1 représente une vue en coupe radiale du cylindre des aiguilles avec un groupe d'électroaimants de sélection, en conformité avec l'invention, dans la position du point "flotté ;
• - la FIG. 2 représente une vue développée du manteau des cames avec les différents groupes de sélection en conformité avec l'invention;
• - la FIG. 3 représente la vue détaillée du groupe de sélection de la Fig. 1 dans la position du point "retenue"; et
• - la FIG. 4 représente la vue détaillée du groupe de sélection de la Fig. 1 dans la position du point "déchargé";
• - la FIG. 5 représente la section suivant la ligne A-A de la Fig. 1 afin de mettre en évidence la fonction de l'électroaimant de sélection et d'une came de pression;
• - la FIG. 6 représente la vue en coupe dans un plan horizontal d'un électroaimant avec les aimants permanents correspondants;
• - la FIG. 7 représente la vue en coupe suivant la ligne B-B de la Fig. 6;
• - la FIG. 8 représente la vue en coupe suivant la ligne C-C de la Fig. 6.

These advantages and characteristics as well as others will be more and better understood by each person skilled in the art in the light of the description which follows and with the aid of the appended drawings given by way of practical example of the invention, but to do not consider in the limiting sense; drawings in which:

• - FIG. 1 shows a view in radial section of the needle cylinder with a group of selection electromagnets, in accordance with the invention, in the position of the "float"point;
• - FIG. 2 shows a developed view of the cam coat with the various selection groups in accordance with the invention;
• - FIG. 3 shows the detailed view of the selection group of FIG. 1 in the position of the "hold"point; and
• - FIG. 4 shows the detailed view of the selection group of Fig. 1 in the position of the "unloaded"point;
• - FIG. 5 shows the section along line AA in FIG. 1 in order to highlight the function of the selection electromagnet and of a pressure cam;
• - FIG. 6 shows the sectional view in a horizontal plane of an electromagnet with the corresponding permanent magnets;
• - FIG. 7 shows the sectional view along line BB of FIG. 6;
• - FIG. 8 shows the sectional view along the line CC of FIG. 6.

Reduced to its essential structure and with reference to Figures 1 and 2 of the accompanying drawings, a selection device, needle by needle, in a circular knitting machine with reciprocating movement, in accordance with the present invention, comprises:
- a cylinder 1 with needles 2 and sub needles on keys 4;
- a pusher or pusher jack 6, associated with each key 4, which is rigid and has ends 7,8 in the shape of a heel and which is further pushed towards the outside of the cylinder 1 by a spring 9 which is fixed to a end 10 to cylinder 1 and which has a corrugated profile with two convexities 10a and 10b for contact, respectively, with the upper and lower zones of said pusher jack 6;
- two oscillating selectors 11,12 made of ferromagnetic material, superimposed vertically, of the same shape, but symmetrical with respect to a horizontal line of separation, which are oscillating around a respective support point 13 median and with their respective back part oriented against the face of the pusher jack 6 so as to maintain the latter in its housing.

Each of said selectors 11, 12 has a mixtilinear profile, with a convexity 14 for contact with the pusher jack 6, with a first end heel 15 for contact with a pressure cam 25, 26, with a second median heel 16 which constitutes the anchor of attraction of the electromagnetic selection system and with a third heel 17 for contact with a spacer ring 18, made of non-magnetic material and rotating in accordance with the cylinder of the needles, and whose role will be specified thereafter;
several electromagnetic selection groups, each positioned between two consecutive power supplies 27 and comprising:
- Two electromagnets 21, 22, one upper and the other lower, which are intended to act on the middle heels 16 of the above-mentioned oscillating selectors, upper 11 and lower 12, respectively; and each of the electromagnets 21,22 being interposed between two permanent retaining magnets 23a, 23b and 24a, 24b, respectively;
two pressure cams 25, 26, one upper and the other lower, arranged on the same vertical passing through the axis of each group of electromagnets 21, 22, and whose symmetrical profiles 25a, 25b and 26a, 26b are intended to cooperate with the heel 15 of the oscillating selector corresponding, upper 11 and lower 12, respectively.

Such an arrangement of the electromagnets 21, 22 and the pressure cams 25, 26 makes it possible to use electromagnets having poles 28 of considerably increased cross-section compared to those used today for electromagnetic selection and to position said cams, with the vertex 29 which has a length less than that of the poles, directly in correspondence with the selection electromagnets 21, 22 without any risk of interference from the adjacent permanent magnets;
- A fixed coat of cams and comprising: two cams 30, 31, one upper and the other lower, intended to act on the heel respectively, upper and lower of the pusher jacks 6 selected; each of said cams 30,31 is arranged angularly equidistant between two consecutive selection groups and with the two symmetrical profiles 30a, 31a and 30b, 31b, respectively on the vertical of the respective permanent magnets 23a, 24a and 23b, 24b.

The cam 31 has a height such as to raise the lower heel 8 of the jacks 6 selected by the corresponding oscillating selector 12 not attracted, from the lower position A of floating point, to the intermediate position B of retained point (see Fig. 3); and the cam 30 has a height capable of lifting the upper heel 7 of the jacks 6 selected by the corresponding oscillating selector 11 not attracted, the lower position A of the floating point, to the upper position C of the discharged point (see Fig. 4). The cam coat also includes traditional cams 34 for lowering the heels 5 of the wedge 4 and those 35 for lowering the heel 3 of the needles 2 during the formation of the mesh.

The operation is as follows. With the cylinder 1 of the needles rotating in the direction of the arrow F, in correspondence with the selection group 21, 22, the oscillating selectors 11 and 12 are actuated by the profiles 25a and 26a of the respective pressure cams 25 and 26, likewise the heels 17 of said selectors come into contact with the ring 18 and the convexities 14 push the pusher jack 6 towards the inside of the cylinder, overcoming the elastic resistance of the spring 10. Thanks to the presence of the ring 18, the heels 16 selectors 11,12 are kept slightly away from the respective electromagnets 21,22 even when they are attracted by them, so as to avoid wear of the electromagnets and magnets and to reduce friction, but keeping in the at the same time all the magnetic attraction of the electromagnets themselves, also thanks to the larger cross section of the poles.

Under these conditions, there are three selection possibilities:

1st selection (for the "float" point).

The two electromagnets 21 and 22 are excited, and the oscillating selectors 11, 12, after having left the pressure cams 25 and 26, remain attracted by the electromagnets and, then by the permanent magnets 23b and 24b, that is to say tell those which are downstream of the electromagnets, in the direction of movement, so that the heels, upper 7 and lower 8, of the pusher jack 6 are retracted; in this position (see Fig. 1) they pass behind the cams 30 and 31, continuing in the lower position A until the next selection group, while the needle 2 remains out of service.

2nd selection (for the "retained" point).

The lower electromagnet 22 is de-energized and abandons the heel 16 of the lower oscillating selector 12 so that the lower heel 8 of the pusher jack 6, pushed by the spring 10, engages the cam 31 (see FIG. 3), thereby cooperating the thrust of the spring 10 and the pressure cam 25, while the permanent magnet 23b located downstream of the electromagnet remains without effect. In this position the lower selector 12 is attracted by the permanent magnet 24b located downstream of the electromagnet 22 and the lower heel 8 of the pusher jack 6 cooperates with the profile 31b of the cam 31 and is raised in the intermediate position B , while the upper heel passes behind the cam 30. Meanwhile the cam 35 guides the heel 3 of the needle 2 for the formation of the retained point.

Then the cam 34 is responsible for bringing the key 4 and the pusher jack 6 to the lower position A for the following selection.

3rd selection (for the "unloaded" point).

None of the electromagnets 21 and 22 is excited; the two oscillating selectors 11,12 guided by the pressure cams 25 and 26 and under the pressure of the spring 10, return to the selection position (see Fig. 4). In this position, the profile 30b of the cam 30 which is located slightly upstream, in the direction of movement of the cylinder, that 31b of the cam 31, cooperates with the heel 7 of the pusher jack 6 and lifts it up into the upper position C, while the needle 2, thanks to the mesh forming cam 35, performs an unloaded stitch. Then the key 4 and the pusher jack 6 are lowered by the cam 34 in the lower position A for the next selection.

In the opposite direction of movement of the cylinder of the needles 1, that is to say according to the arrow S, the operation and the selection are carried out in exactly the same way, but the permanent magnets used and the active profiles of the cams 30 , 31 are those 23a, 24a and 30a, 31a because located upstream in the direction of movement of the electromagnets 21, 22.

Claims (6)

1) Electromagnetic selection device with electronic control of needles with three positions for circular knitting machine with reciprocating movement, comprising a cylinder (1) with needles (2), key (4), pusher jacks (6) and oscillating selectors (11 , 12) and corresponding pressure cams (25,26) and, for each supply, comprising two electromagnets (21,22) interposed between two permanent magnets (23a, 23b) (24a, 24b) for the selection of oscillating selectors (11 , 12), a first cam (31) for controlling the push jacks (6) in the lower position for the retained point, a second cam (30) for controlling the keys (4) in the upper position for the unloaded point and a third cam (35) for controlling the needles (2) for forming the mesh, characterized in that said pusher jacks (6) consist of a rectilinear body with the two ends, lower and upper, in shape heel (7.8) and to which is associated with at least one posterior spring (10) with centrifugal action; in that said ocular selectors (11,12) are arranged superimposed vertically and symmetrically with respect to the horizontal line of separation, with a convexity (14) towards the corresponding pusher jack (6) and with three heels oriented towards the outside of the cylinder (1), two end (15,17) for contact with a pressure cam (25,26) and a spacer ring (18) respectively, and an intermediary (16) for magnetic attraction; in that said electromagnets (21,22) for selecting the oscillating selectors (11,12) are arranged superimposed on the same vertical and each with the poles juxtaposed at the intermediate heel (16) of the corresponding selector (11,12); in that said pressure cams (25,26) are arranged on the same vertical and in axis with said electromagnets (21,22); in that said cam (30) is provided for the excursion of the upper heel (7) of the pusher jacks (6) and of the superimposed heel (5) of the key (4). 2) Selection device according to claim 1, characterized in that said pusher jacks (6) are rigid. 3) Selection device according to claim 1, characterized in that said spring (10) has a curvilinear profile with two convexities towards the corresponding pusher jack (6), which are symmetrical with respect to three convexities towards the cylinder (1) needles and so as to act at two symmetrical and diametrically opposite points of the pusher jack (6). 4) Selection device according to claim 1, characterized in that said pressure cams (25,26) have an apex (29) of development less than the width of the poles (28) of said electromagnets (21,22). 5) Selection device according to claim 1, characterized in that said spacer ring (18) is in a position such that it prevents friction of the heel (16) of the oscillating selectors (11,12) on the poles (28) of the electromagnets (21,22) and in that it rotates in accordance with the cylinder (1) of the needles. 6) Circular knitting machine with reciprocating movement provided with a selection device according to one or more of Claims 1 to 5.

Images