A DRIVE CHAIN FOR STITCH FORMATION MEMBERS OF A CIRCULAR KNITTING MACHINE AND A CIRCULAR KNITTING MACHINE COMPRISING SUCH DRIVE CHAIN

Abstract

A drive chain for stitch formation members of a circular knitting machine includes an element coupled or to be coupled with a stitch formation member, and an oscillating lever connected to said element on a junction area. The oscillating lever is configured for interacting with selecting devices so as to oscillate with respect to said element. The element comprises a first portion carrying a first butt and a second portion configured for slidingly coupling with a bottom of a respective groove. The first portion is elastically coupled with the second portion so as to keep the first butt in an operating position in which the first butt protrudes from the groove and to allow the first butt to get back into the groove in case of interference with one of the first actuating cams.

Claims

1. A drive chain for stitch formation members of a circular knitting machine, comprising: an element (6) incorporating a stitch formation member or operatively coupled or to be coupled with a stitch formation member; wherein said element (6) has a first butt (18) configured for engaging into first paths (26) defined by first actuating cams (25) of a circular knitting machine; an oscillating lever (7) connected to said element (6) on a junction area and extending, with respect to said element (6), on the opposed side to said stitch formation member; the oscillating lever (7) exhibiting a second butt (22); wherein the oscillating lever (7) is configured for interacting with at least one selecting device (23) of the circular knitting machine so as to oscillate with respect to said element (6) between an extracted position, in which the second butt (22) is taken out of a respective groove (5) of a support of the circular knitting machine and is engaged with second paths (28) defined by second actuating cams (27), and a retracted position, in which the second butt (22) is retracted into the respective groove (5) so as not to engage into said second paths (28); wherein the element (6) exhibiting the first butt (18) comprises a first portion (9) carrying the first butt (18) and a second portion (10) configured for slidingly coupling with a bottom of the respective groove (5); wherein the first portion (9) is elastically coupled with the second portion (10) so as to keep the first butt (18) in an operating position in which said butt (18) protrudes from the groove (5) and to allow the first butt (18) to get back into the groove (5) in case of interference with one of the first actuating cams (25).

2. The drive chain according to claim 1, wherein the element (6) exhibiting the first butt (18) comprises an elastic joint (11) connecting the first portion (9) to the second portion (10) so that the first portion (9) can elastically rotate with respect to the second portion (10); optionally wherein the elastic joint (11) is a torsion spring.

3. The drive chain according to claim 2, wherein the elastic joint (11) is placed in correspondence of the junction area.

4. The drive chain according to claim 2, wherein the oscillating lever (7) is hinged to said element (6) on a rotation pivot (8) placed at the junction area; wherein the elastic joint (11) delimits the rotation pivot (8); optionally wherein the rotation pivot (8) basically coincides with a center of rotation of the first portion (9) with respect to the second portion (10).

5. The drive chain according to claim 2, wherein the elastic joint (11) exhibits a C or open ring shape.

6. The drive chain according to claim 1, wherein, along a main direction of development of the drive chain (3), the junction area is placed between the stitch formation member and the first butt (18).

7. The drive chain according to claim 1, wherein the first portion (9) mainly develops from the junction area to the second butt (22) and exhibits an edge (19) facing the oscillating lever (7); wherein the edge (19) is configured for engaging with the oscillating lever (7) and shifting said oscillating lever (7) to the retracted position, when the first butt (18) gets back into the groove (5).

8. The drive chain according to claim 2, wherein the first portion (9) comprises a stroke end (15) arranged, along a main direction of development of the drive chain (3), between the elastic joint (11) and the stitch formation member; wherein, when the first butt (18) is in the operating position, the stroke end (15) rests against the bottom of the respective groove (5) and, when the first butt (18) gets back into the groove (5), the stroke end (15) gets away from the bottom of the respective groove (5).

9. The drive chain according to claim 2, wherein the first portion (9) comprises a part (14) arranged, along a main direction of development of the drive chain (3), between the elastic joint (11) and the stitch formation member; said part (14) exhibiting a height basically corresponding to a depth of the groove (5); wherein said part (14) has a radially outer edge (16) that is rounded so as to never protrude from the groove (5) even when the first portion (9) rotates with respect to the second portion (10); optionally wherein said part (14) exhibits an arc shape and is arranged partially around the elastic joint (11).

10. The drive chain according to claim 9, wherein said part (14) comprises the stroke end (15).

11. The drive chain according to claim 1, wherein the oscillating lever (7) exhibits at least one selecting tooth (21) configured for interacting with at least one arm (24) of a selecting device (23) of arm type; or wherein the oscillating lever (7) exhibits a distal segment (33) configured for interacting with a selecting device (31) of magnetic type.

12. A circular knitting machine, comprising: a support having a plurality of grooves (5) arranged around a central axis (X-X) of said support; a plurality of stitch formation members, each being housed at least partially in a respective groove (5); first actuating cams (25) and second actuating cams (27) facing the grooves (5); wherein the support is movable with respect to the first actuating cams (25) and second actuating cams (27) around the central axis (X-X) so as to determine or enable the movement of the stitch formation members along the grooves (5) for stitch formation by said stitch formation members; a plurality of drive chains (3), each being carried out according to claim 1, housed in a respective groove (5) and integrating a stitch formation member or operatively coupled or to be coupled with a stitch formation member; at least one selecting device (23; 31) interacting with the drive chains (3).

13. The machine according to claim 12, wherein the first actuating cams (25) comprise at least one deviating cam (29) configured for interacting with the first butt (18) and directing it into one of the first paths (26) or in another one of the first paths (26); wherein said deviating cam (29) exhibits a ramp (30) configured for progressively pushing the first butt (18) into the groove (5) in case of interference with said deviating cam (29).

14. The machine according to claim 12, 13, wherein said at least one selecting device (23) is of arm type and interacts with a selecting tooth (21) carried by the oscillating lever (7) of the drive chain (3); or wherein said at least one selecting device (31) is of magnetic type and interacts with a distal segment (33) of the oscillating lever (7) of the drive chain (3) configured for elastically bending.

15. The machine according to claim 12, wherein the stitch formation member integrated into or operatively coupled or to be coupled with the drive chain (3) is a needle (2) or a sinker or a punch or a reed or a hook.

16. The drive chain according to claim 2, wherein the first portion (9) comprises a stroke end (15) arranged, along a main direction of development of the drive chain (3), between the elastic joint (11) and the stitch formation member; wherein, when the first butt (18) is in the operating position, the stroke end (15) rests against the bottom of the respective groove (5) and, when the first butt (18) gets back into the groove (5), the stroke end (15) gets away from the bottom of the respective groove (5), and wherein the first portion (9) comprises a part (14) arranged, along a main direction of development of the drive chain (3), between the elastic joint (11) and the stitch formation member; said part (14) exhibiting a height basically corresponding to a depth of the groove (5); wherein said part (14) has a radially outer edge (16) that is rounded so as to never protrude from the groove (5) even when the first portion (9) rotates with respect to the second portion (10); optionally wherein said part (14) exhibits an arc shape and is arranged partially around the elastic joint (11).

Description

DESCRIPTION OF THE DRAWINGS

[0108] This description shall be made below with reference to the accompanying drawings, provided to a merely indicative and therefore non-limiting purpose, in which:

[0109] FIG. 1 shows a magnified portion of a detail of a circular knitting machine, in which drive chains according to the present invention are shown schematically, and needles paired with actuating cams;

[0110] FIGS. 2, 3, 4 and 5 show one of the drive chains of FIG. 1 housed in a groove, in respective side views and in respective operating configurations;

[0111] FIGS. 6, 7 and 8 show a variant of the drive chain as in the previous figures in respective operating configurations;

[0112] FIG. 8A shows the variant of FIGS. 6, 7 and 8 with a distal segment modified;

[0113] FIGS. 9A and 9B show a different embodiment of the drive chain according to the present invention;

[0114] FIG. 10 is a magnified view of a part of the cams of FIG. 1;

[0115] FIG. 11 is a sectioned view according to plane XI-XI of FIG. 10;

[0116] FIG. 12 is a sectioned view according to plane XII-XII of FIG. 10;

[0117] FIGS. 13 and 14 show the cams of FIG. 1 with the drive chains in respective operating conditions;

[0118] FIGS. 15 to 17 show the cams of FIGS. 13 and 14 with the drive chains during a fault condition; and

[0119] FIGS. 18 to 29 show further variants of the drive chain according to the present invention.

DETAILED DESCRIPTION

[0120] With reference to the figures mentioned above, the drive chain according to the present invention is described in an exemplary and non-limiting manner with reference to its application in a needle-holding plate associated with respective actuating cams of a circular knitting machine for manufacturing fabrics, which is not shown as a whole.

[0121] As is known, the circular knitting machine comprises a basement constituting the supporting structure of the machine. A needle-holding cylinder is mounted vertically to the basement and has a plurality of longitudinal grooves obtained on a radially outer surface thereof. The longitudinal grooves are arranged around a central axis X-X of the needle-holding cylinder and usually develop parallel to said central axis X-X. Each longitudinal groove houses respective drive chain, comprising a plurality of flat parts and, at least partially, a respective needle. Actuating cams are arranged as a casing around the needle-holding cylinder and lie facing the radially outer surface of the cylinder and thus the longitudinal grooves and the drive chains. These actuating cams delimit tracks/paths arranged on an inner surface of the casing. The machine here described by way of example further comprises a needle-holding plate exhibiting a plurality of grooves developing radially with respect to the central axis X-X. Each radial groove houses a respective needle and a respective drive chain comprising a plurality of flat parts. Actuating cams supported by a disc face the needle-holding plate and the radial grooves and delimit respective tracks/paths. The needle-holding cylinder and the needle-holding plate are rotated (arrow R of FIG. 1) around the central axis X-X by a motor, while the casing and the disc with the actuating cams are fixed. The needles and/or drive chains are provided with butts engaged/to be engaged into the tracks/paths, so that the relative rotation between the needle-holding cylinder and the casing and between the needle-holding plate and the disc causes the needles to shift in the respective longitudinal and radial grooves. Selecting devices interact with the drive chains arranged in the longitudinal grooves and in the radial grooves so as to selectively actuate the needles so that they go along given tracks/paths and enable stitch formation, i.e. fabric production.

[0122] FIG. 1 shows a lower portion of the disc associated with the needle-holding plate and referred to with numeral 1. The disc 1 exhibits the actuating cams delimiting tracks/paths which develop circumferentially around the central axis X-X. FIG. 1 further shows schematically needles 2 and drive chains 3 according to the present invention, which are associated with the cams/tracks/paths and are housed in the radial grooves of the needle-holding plate, not shown in FIG. 1, which lies facing the disc 1.

[0123] FIGS. 2, 3, 4 and 5 show, in a section according to a radial plane containing the central axis X-X, a portion of the needle-holding plate 4 and of the disc 1 and one of the drive chains 3 according to the present invention associated with the respective needle 2. The drive chain 3 is housed in a respective radial groove 5 of the needle-holding plate 4 and is open upwards. The disc 1 with the actuating cams is arranged above the needle-holding plate 4 and the tracks/paths delimited by the actuating cams face the radial grooves 5.

[0124] The drive chain 3 shown in FIGS. 2-5 comprises an element 6 (referred to as sub-needle in the specific case) to be operatively coupled with the respective needle 2, and an oscillating lever 7 hinged to said element 6 on a rotation pivot 8 defining an axis of rotation of the oscillating lever 7 which is orthogonal to the radial plane containing the central axis X-X. The rotation pivot 8 defines a junction area between the oscillating lever 7 and the element 6.

[0125] In the example shown here, the needle 2 is at a distance from the drive chain 3 and is configured for contacting said element 6 and being pushed by the drive chain 3 during the operation of the circular knitting machine. The oscillating lever 7 extends, with respect to said element 6, on the opposite side of the needle 2. The element 6 comprises a first portion 9 and a second portion 10 connected to one another by means of an elastic joint 11. The first portion 9, the second portion 10 and the elastic joint 11 are made as one piece.

[0126] The second portion 10 comprises a segmented shaped like a flattened rod resting upon and sliding against a bottom of the groove 5. The elastic joint 11 is located at an end of the segment shaped like a flattened rod and exhibits a C or open ring shape. The C shape develops continuously from the segment shaped like a flattened rod and ends joining the first portion 9. In other words, and end of the C shape is connected to the segment shaped like a flattened rod and an opposite end of the C shape is connected to the first portion 9. In the embodiment shown, an elastically deformable distal segment 12 develops from an end of the segment shaped like a flattened rod in an opposite direction to the one carrying the elastic joint 11. Also the elastically deformable distal segment 12 has a thin shape and exhibits its own distal end 13 at a distance from the bottom of the groove 5.

[0127] The first portion 9 comprises an arc shaped part 14, e.g. a sickle shape part, developing mainly between the elastic joint 11 and the needle 2 and arranged partially around said elastic joint 11, so that said part 14 and said elastic joint 11 delimit an arc shaped slot between them. This arc shaped slot extends from the bottom of the groove 5 and for about 220-230 around the ring shape constituting the elastic joint 11. The arc shaped part 14 exhibits a height basically corresponding to a depth of the groove 5. An edge of said part 14 faces the bottom of the groove 5 and, as better shown below, defined a stroke end 15. The stroke end 15 is arranged, along a main direction of development of the drive chain 3, between the elastic joint 11 and the needle 2.

[0128] A radially outer edge 16, with respect to the arc shaped slot and to the open ring, of the arc shaped part 14 is rounded.

[0129] The first portion 9 develops mainly from the rotation pivot 8 towards the distal end 13 of the elastically deformable distal segment 12. In particular, the first portion 9 comprises a tapered shape part 17 which is made as one piece with the arc shaped part 14 and extends from the elastic joint 11 towards the distal end 13. This tapered shape part 17 exhibits an outer edge, with respect to the groove 5, on which a first butt 18 is obtained and which has an edge 19 facing the inside of the groove 5.

[0130] The elastic joint 11 is basically a torsion spring allowing the first portion 9 to rotate elastically, within certain limits, with respect to the second portion 10.

[0131] The oscillating lever 7 exhibits a proximal end 20 with a partially circular shape, which is housed inside the elastic joint 11. The C shaped elastic joint 11 partially surrounds the proximal end 20 of the oscillating lever 7, so that said proximal end 20 can rotate inside the elastic joint 11. Therefore, the elastic joint 11 also delimits, together with the proximal end 20, the rotation pivot 8 of the oscillating lever 7 as described above.

[0132] The oscillating lever 7 extends beyond the distal end 13 of the elastically deformable distal segment 12 of the second portion 10 and exhibits an outer edge, with respect to the groove 5, on which at least one selecting tooth 21 and a second butt 22 are obtained. The second butt 22 is located at a distal end of the oscillating lever 7 and the selecting tooth 21 is located between the tapered shape part 17 and said second butt 22.

[0133] Along a main direction of development of the drive chain 3, i.e. along a direction of development of the groove 5, the rotation pivot 8 of the drive chain 3 is located between the needle 2 and the first butt 18 and is closer to said needle 2 than to the first butt 18 and to the second butt 22. For instance, given Y a distance between an area of interaction of the needle 2 with the drive chain 3 and the rotation pivot 8 (which coincides with the elastic joint 11), and given X a distance between the elastic joint 11 and the first butt 18, a ration X/Y is greater than 1, e.g. this ratio X/Y is between 2 and 5. Moreover, given Z a distance between the rotation pivot 8 and the second butt 22, a ratio Z/X is greater than 1, e.g. this ratio Z/X is between 2 and 6.

[0134] As can be seen in FIG. 2-5, the distal end 13 of the elastically deformable distal segment 12 of the second portion 10 rests against the oscillating lever 7 and is configured for pushing the oscillating lever 7, in particular the selecting tooth 21 and the second butt 22, out of the groove 5, i.e. for pushing and keeping said oscillating lever 7 in the extracted position.

[0135] The selecting tooth 21 is configured for interacting with at least one arm 24 of a piezoelectric selecting device 23 of arm type. FIG. 1 shows four piezoelectric selecting devices 23 of arm type which are mounted integrally to the disc 1 and to the actuating cams. The piezoelectric selecting device 23 of arm type is known per se and comprises an array of arms 24 protruding from a front face of the piezoelectric selecting device 23 and facing the needle-holding plate, the radial grooves 5 and the selecting teeth 21 of the oscillating levers 7. One of these arms 24 is also represented in FIG. 3.

[0136] As can be seen in FIG. 1, the array of arms 24 of each piezoelectric selecting device 23 comprises a plurality of arms 24 aligned along a respective common radial direction. Each of the arms 24 can be oscillated, e.g. by means of a piezoelectric control managed by the control unit of the machine, around a respective axis orthogonal to the common radial direction, between a first position and a second position. By means of said oscillation, the arm 24 is moved so as to interact or not with the selecting tooth 21 of the oscillating lever 7. The actuating cams supported by the disc 1 comprise first actuating cams 25 delimiting first paths 26 and configured for interacting with the first butt 18, and second actuating cams 27 delimiting second paths 28 and configured for interacting with the second butt 22.

[0137] The oscillating lever 7 with the second butt 22 rotates around the rotation pivot 8 and oscillates as a result of the combined action: of the distal end 13 of the elastically deformable distal segment 12, which pushes the oscillating lever 7 towards the outside of the groove 5; of the piezoelectric selecting devices 23, which with the arms 24 push the oscillating lever 7 into the groove 5; of the second actuating cams 27, which have ramps also shaped for pushing and keeping the oscillating lever 7 inside the groove 5. As a result of these actions, the oscillating lever 7 oscillates between an extracted position, in which the second butt 22 is taken out of the respective groove 5 and is engaged with the second paths 28 defined by the second actuating cams 27, and a non-operating position, in which the second butt 22 is retracted into the respective groove 5 so as not to engage into said second paths 28.

[0138] The first portion 9 of the element 6 rotates with respect to the second portion 10 on the elastic joint 11 as a result of the combined action of the elastic force exerted by the elastic joint 11, which moves the tapered shape part 17 with the first butt 18 in a direction pointing out of the groove 5, and of the first actuating cams 25. The elastic joint 11 is configured for leaving a minimal clearance at the proximal end 20 of the oscillating lever 7 even when said elastic joint 11 is in a configuration of maximum torsion. Thus, the minimum operating clearance allows the rotation pivot 8 to rotate even when the elastic joint 11 reaches its maximum torsion.

[0139] FIG. 2 (drive chain 3 operating-O condition/configuration) shows the drive chain 3 with the oscillating lever 7 in the extracted position. A surface of the second actuating cam 27 facing the groove 5 prevents the oscillating lever 7 from getting out further from said groove 5, and the elastically deformable distal segment 12 keeps the oscillating lever 7 in this position by pushing the distal end of the oscillating lever 7 against said surface of the second actuating cam 27 facing the groove 5. Said distal end of the oscillating lever 7 slides against the second actuating cam 27 due to the relative rotational motion of the needle-holding plate 4 with respect to the second actuating cams 27. The first butt 18 is in an operating position in which it protrudes from the groove 5 and is housed in one of the first paths 26. The elastic joint 11 is in a basically unloaded torsion condition or is pre-loaded, i.e. it tends to push in a counter-clockwise direction (looking at FIG. 2) the tapered shape part 17, which thus rests and slides (due to the relative rotational motion of the needle-holding plate 4 with respect to the first actuating cams 25) against a surface of the first actuating cams 25 facing the groove 5, whereas the stroke end 15 rests against the bottom of said groove 5.

[0140] FIG. 3 (drive chain 3 with piezoelectric selecting device 23 under selection-S condition/configuration) shows the drive chain 3 with the oscillating lever 7 in the retracted position due to the interaction of one of the arms 24 of the piezoelectric selecting device 23 with the selecting tooth 21 of the oscillating lever 7. The first butt 18 is in the same operating position as in FIG. 2.

[0141] FIG. 4 (drive chain 3 with oscillating lever 7 embedded-A condition/configuration) shows the drive chain 3 with the oscillating lever 7 in the retracted position due to the interaction with one of the second actuating cams 27. The oscillating lever 7, moved to the retracted position by the piezoelectric selecting device 23 (as shown in FIG. 2) or as a result of engaging a ramp of one of the second actuating cams 27, is retained in this retracted position by the second butt 22 which rests and slides against the surface of the second actuating cam 27 facing the groove 5. The first butt 18 is still in the same operating position as in FIG. 2.

[0142] FIGS. 13 and 14 show by way of example the paths followed by the drive chains 3 (which are shown schematically with the respective first butt 18 and second butt 22) only, for loop formation (FIG. 13, withdrawn path) and for stitch formation (FIG. 14, operating path), respectively. In these FIGS. 13 and 14, the letters O, S, A associated with each position of the drive chains 3 indicate the condition/configuration of the drive chain 3 among those described above and shown in FIGS. 2, 3 and 4.

[0143] FIG. 5 (contact of first butt 18-C condition/configuration) shows the drive chain 3 in case of interference with one of the first actuating cams 25, i.e. if the first butt 18, instead of correctly taking a first path 26 delimited by the first actuating cams 25, by touching or sliding over a first actuating cam 25, hits the first actuating cam 25 itself.

[0144] For instance, as shown in FIG. 15, if due to a fault the second butt 22 of the oscillating lever 7 leaves the respective second (lifting) actuating cam 27 at about half of its lifting path, the first butt 18, instead of correctly taking one of the first paths 26 delimited above and below a deviating cam 29 (the deviating cam 29 placed below in FIG. 10) belonging to the first actuating cams 25, hits said deviating cam 29. This deviating cam 29 (shown more clearly in FIGS. 10 and 11) exhibits a ramp 30 developing from a bottom surface of the first paths 26. The first path 18 engages the ramp 30 and slides over the ramp 30 (FIG. 11) and thus the ramp 30 progressively pushes the first butt 18 into the respective groove 5, as shown in FIG. 5.

[0145] The presence of the ramp 30 therefore avoids a violent contact of the first butt 18 with the deviating cam 29, though instead this ramp 30 engages and supports the first butt 18 while getting back into the groove 5. The interaction between the ramp 30 and the first butt 18 causes a rotation of the first portion 9 of the element 6 operatively coupled or to be coupled with the respective needle 2 around the center of rotation coinciding with the rotation pivot 8 (in clockwise direction in FIG. 5). The stroke end 15 gets away from the bottom of the respective groove 5 and the edge 19 of the tapered shape part 17 contacts the oscillating lever 7 and pushes and retains it in the non-operating position, thus contrasting the elastic action exerted by the elastically deformable distal segment 12. The radially outer, rounded edge 16 does not protrude from the groove 5 even when the first portion 9 rotates with respect to the second portion 10.

[0146] In FIG. 15, the letter C indicates the position of the drive chains 3 in C condition/configuration of FIG. 5. In the first useful space, i.e. when it finds one of the first paths 26, the first butt 18, pushed by the elastic joint 11, gets out again of the groove 5 and resumes one of the first programmed paths 26 without damage to the drive chain 3.

[0147] In FIG. 16, the second butt 22 of the oscillating lever 7 follows the whole of the second actuating cam 27 placed more to the left, but then leaves the second actuating cam 27 placed more the right at about half of its lifting path. The first butt 18, instead of correctly taking one of the first paths 26 delimited above or below a deviating cam 29 (the deviating cam 29 placed higher in FIG. 10) belonging to the first actuating cams 25, hits said deviating cam 29. Also this deviating cam 29 (shown more clearly in FIGS. 10 and 11) exhibits a ramp 30 developing from a bottom surface of the first paths 26. The first path 18 engages the ramp 30 and slides over the ramp 30 (FIG. 12) and thus the ramp 30 progressively pushes the first butt 18 into the respective groove 5, as shown in FIG. 5.

[0148] Here again, in the first useful space, i.e. when it finds one of the first paths 26, the first butt 18, pushed by the elastic joint 11, gets out again of the groove 5 and resumes one of the first programmed paths 26 without damage to the drive chain 3.

[0149] FIG. 17 shows a situation like the one in FIG. 16, but here the first butt 18 gets again out of the groove 5 and resumes one of the first paths 26 in a different place.

[0150] FIGS. 6, 7 and 8 show a variant of the drive chain 3 of FIGS. 2, 3, 4 and 5. This variant is structured so as to operate with selecting devices of magnetic type instead of piezoelectric selecting devices 23 of arm type as described above. The magnetic selecting device 31 shown in FIGS. 6, 7 and 8 comprises two magnets 32. The drive chain 3 of FIGS. 6, 7 and 8 differs from the one of FIGS. 2, 3, 4 and 5 in that the oscillating lever 7 is without the selecting tooth 21 and comprises instead a distal segment 33 extending beyond the second butt 22 and configured for bending elastically and interacting with the two magnets 32.

[0151] FIG. 6 shows the O condition/configuration, corresponding to the one in FIG. 2, in which the two magnets 32 are deactivated and do not attract said distal segment 33. FIG. 7 shows the S condition/configuration, corresponding to the one in FIG. 3, in which the two magnets 32 are active and retain the distal segment 33 so as to bend it elastically and to pre-load said distal segment 33 against the magnets 32. FIG. 8 shows the C condition/configuration, corresponding to the one in FIG. 5, in which the distal segment 33 is pre-loaded against the magnets 32, like in FIG. 7, and the first butt 18 is inserted into the groove 5.

[0152] The drive chain 3 of FIG. 8A is basically the same as the one shown in FIGS. 6, 7 and 8, except for the fact that the distal segment 33 is stiff, i.e. it does not bend when it is pushed against the magnets 32.

[0153] FIGS. 9A and 9B show a different embodiment of the drive chain 3, which mainly differs from the drive chain of FIGS. 2, 3, 4 and 5 in that the elastic joint 11 is at a distance from the rotation pivot 8. As can be observed, this embodiment exhibits the selecting tooth 21 and is thus structured so as to operate with the piezoelectric selecting devices 23 as described above.

[0154] The elastic joint 11 is located near the needle 2, i.e. at an end of the drive chain 3 positioned on an opposite side with respect to a distal end of the oscillating lever 7 supporting the second butt 22. The elastic joint 11 connects the first portion 9 to the second portion 10 of the element 6 by means of a first curved segment 34 directly connected to the first portion 9, a second curved segment 35 directly connected to the second portion 10 and a rectilinear segment 36 connecting the first curved segment 34 to the second curved segment 35. The first portion 9 extends projecting from the first curved segment 34, is basically parallel to a segment shaped like a flattened rod 37 of the second portion 10 and protrudes towards the rotation pivot 8. The rotation pivot 8 is located between the segment shaped like a flattened rod 37 and the elastically deformable distal segment 12 of the second portion 10. The rotation pivot 8 is positioned at about half a length of the drive chain 3.

[0155] The drive chains 3 according to the present invention have been described so far in detail together with respective needles 2 and with reference to a needle-holding plate, though the present invention may be applied to any stitch formation member (e.g. needles, sinkers, punches, reeds or hooks). For instance, FIGS. 18, 21 and 22 show a sinker 38, FIG. 19 shows a hook 39.

[0156] The present invention may also be applied to any support (e.g. plate or cylinder or crown) of a circular knitting machine having grooves 5 which house the drive chains 3 and the stitch formation members. The grooves 5 of the cylinder are usually parallel to the central axis X-X of the machine, whereas the grooves in the plate or crown are radial with respect to the central axis X-X. Instead of the cylinder with the axial grooves, the support may also be defined by a drum with inclined grooves 5.

[0157] In the embodiment here described in detail, the actuating cams are fixed, i.e. they belong to the fixed disc while the needle-holding plate rotates thanks to the motor. In variants of embodiment falling within the present invention, the support provided with grooves 5 is fixed while the actuating cams are rotated around the central axis by a motor.

[0158] Moreover, the stitch formation member, i.e. the needle 2, has been disclosed so far as a separate member to be coupled with the element 6 of the drive chain 3. Also the sinker of FIG. 18 and the hook of FIG. 19 are separate from the drive chain 3.

[0159] In variants of embodiment, the stitch formation member (needle, sinker, hook, punch, etc.) can also be made as one piece with said element 6, in other words the drive chain 3 incorporates the stitch formation member.

[0160] For instance, a needle 2 integrated in the drive chain 3 is shown in FIG. 20. The needle 2 is made as one piece with the element 6 exhibiting the first butt 18 and develops continuously from the arc shaped part 14. The needle 2 and the first portion 9 are stiffly connected. In case of interference with one of the first actuating cams 25 and of rotation of the first portion 9, also the needle 2 rotates together with the first portion 9. The angle of rotation is however limited and such that the needle 2 does not interfere with other parts of the machine.

[0161] The sinker 38 of FIGS. 21 and 22, conversely, is connected to the element 6 exhibiting the first butt 18 by means of a yielding, elastic connection 40, i.e. a thin, flattened portion which is made again as one piece with the sinker 2 and the drive chain 3. The connection 40 extends along the groove 5, between the arc shaped part 14 and the sinker 38.

[0162] The yielding connection 40 can transmit axial forces, i.e. pointing in the same direction as the groove 5, without deforming, so that the drive chain 3 and the sinker 38 can move axially as one piece.

[0163] The yielding connection 40 is further configured for allowing the rotation of the first portion 9 with respect to the second portion 10 while the sinker 38 is still aligned with the respective groove, i.e. it is not inclined. As shown in FIG. 22, when the first portion 9 rotates, the yielding connection 40 is bent in a radial plane and forms a sort of wave, while the sinker 38 remains where it is, i.e. it is not inclined.

[0164] In variants of embodiment, the stitch formation member exhibits a hook so as to be hooked to the drive chain 3 and, if required, unhooked. For instance, the variant of embodiment shown in FIGS. 23 and 24 is similar to the embodiment shown in FIGS. 2-5, but the arc shaped part 14 is at a greater distance from the elastic joint 11 than the embodiment shown in FIGS. 2-5 and is sized so that the stroke end 15 defines a hook to be engaged into a seat 41 defined by a respective hook obtained in the needle 2. In FIG. 24 the needle 2 is hooked to the drive chain 3. As can be seen in FIG. 23, in case of contact of the first butt 18 and of rotation of the first portion 9 of the element 6, the needle 2 is unhooked from the drive chain 3 and does not rotate (differently from the needle 2 in FIG. 20).

[0165] In variants of embodiment, the oscillating lever 7 is not hinged to the element 6 exhibiting the first butt 18, but it is elastically connected to said element 6 on an auxiliary elastic joint 42 so as to be able to oscillate in any case. For instance, the drive chain 3 of the example of embodiment of FIGS. 25-28 is similar to the one shown in FIGS. 2-5, but differently from the latter, the oscillating lever 7 is connected to the second portion 10 instead of the elastically deformable distal segment 12 and said elastically deformable distal segment 12 is not present. The second portion 10, the auxiliary elastic joint 42 and the oscillating lever 7 are made as one piece. A proximal segment of the oscillating lever 7 ending in the auxiliary elastic joint 42 is inclined with respect to the second portion 10. The auxiliary elastic joint 42 connects said oscillating lever 7 to an end of the second portion 10 and the oscillating lever 7 oscillates between the operating position (FIGS. 25 and 26) and the non-operating position (FIGS. 27 and 28) thank to the auxiliary elastic joint 42 elastically bending. In this exemplary embodiment, differently from the one in FIGS. 2-5, the drive chain 3 can take a configuration in which the first butt 18 is back into the groove 5 and the second butt 22 is in its operating position (FIG. 26), since even when the first portion 9 rotates, the edge 19 does not contact the oscillating lever 7 and cannot push and retain it in the non-operating position.

[0166] FIG. 29 shows a further embodiment of the drive chain 3 which differs from the drive chain in FIGS. 2, 3, 4 and 5 in that the oscillating lever 7 is connected to the element 6 by means of an auxiliary elastic joint 42 located on the elastic joint 11. The proximal end of the oscillating lever 7 is made as one piece with the elastic joint 11 or, in other words, the elastic joint 11 and the auxiliary elastic joint 42 are integrated with each other and the oscillation of the oscillating lever 7 is allowed by an elastic deformation of said auxiliary elastic joint 42. In FIG. 29 a proximal end of the oscillating lever 7 is located inside the C or open ring shape.

[0167] List of elements [0168] 1 Disc [0169] 2 Needle [0170] 3 Drive chain [0171] 4 Needle-holding plate [0172] 5 Radial grooves [0173] 6 Element exhibiting the first butt [0174] 7 Oscillating lever [0175] 8 Rotation pivot [0176] 9 First portion [0177] 10 Second portion [0178] 11 Elastic joint [0179] 12 Elastically deformable distal segment [0180] 13 Distal end of the elastically deformable distal segment [0181] 14 Arc shaped part [0182] 15 Stroke end [0183] 16 Radially outer edge [0184] 17 Tapered shaped part [0185] 18 First butt [0186] 19 Edge [0187] 20 Proximal end of the oscillating lever [0188] 21 Selecting tooth [0189] 22 Second butt [0190] 23 Piezoelectric selecting device [0191] 24 Arm [0192] 25 First actuating cams [0193] 26 First paths [0194] 27 Second actuating cams [0195] 28 Second paths [0196] 29 Deviating cam [0197] 30 Ramp [0198] 31 Magnetic selecting device [0199] 32 Magnets [0200] 33 Distal segment of the oscillating lever [0201] 34 First curved segment [0202] 35 Second curved segment [0203] 36 Rectilinear segment [0204] 37 Segment shaped like a flattened rod [0205] 38 Sinker [0206] 39 Hook [0207] 40 Yielding connection [0208] 41 Seat [0209] 42 Auxiliary elastic joint [0210] X-X Central axis