Classifications

• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B15/00—Details of, or auxiliary devices incorporated in, weft knitting machines, restricted to machines of this kind
  • D04B15/32—Cam systems or assemblies for operating knitting instruments
• • D—TEXTILES; PAPER
  • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
  • D04B—KNITTING
  • D04B15/00—Details of, or auxiliary devices incorporated in, weft knitting machines, restricted to machines of this kind
  • D04B15/66—Devices for determining or controlling patterns ; Program-control arrangements
  • D04B15/80—Devices for determining or controlling patterns ; Program-control arrangements characterised by the thread guides used

Definitions

• the present invention refers to the field of circular knitting machines.
• the loop forming process occurs by means of needles arranged in respective small guiding channels uniformly distributed on the periphery of a rotating cylinder.
• the needles move in the channels with an alternating motion, drawn through a respective "butt” actuated by a series of stationary cams mounted on specific cam-holders surrounding the cylinder.
• These cams present one or more channels, inside which the needle butts move and which define the work path of the needles.
• various types of needles are used, distributed on the cylinder periphery and differing from each other in length, i.e. presenting the butt at different distances from the hook.
• a respective cam channel (P1 , P2, figure 2) is provided, suitable to define different work paths for the various types according to the knit pattern requirements or other.
• FIG 1 two types of needle are shown by way of example: a first needle type A1 provided with a butt T1 suitable to be controlled with the cams of the track P1 (figure 2); and a second needle type A2, provided with a butt T2 suitable to be controlled with the cams of the track P2, these cam tracks being mounted on the cam-holders S fixed to the bearing structure B of the machine.
• the number of needle types can be greater than two and, for this type of machines, can also be five.
• Figure 3 shows the looping in a known machine at any of the yarn feedings of the machine.
• the arrow F indicates the direction of rotation of the needle cylinder
• C indicates the upper edge of the cylinder
• A indicates the needles
• G a thread guide suitable to put a thread H towards the needles.
• Figure 5 shows in enlarged scale the situation of figures 3 and 4.
• the needles in the descending phase have been indicated with numbers 1 to 4.
• Number 2 indicates the needle going below the cylinder edge to form a new loop of stitch and casting off the previously formed stitch.
• the needle 3 in its phase of forming the stitch loop, is still going down, as shown in figure 5 by the arrow FA arranged above it. This needle therefore takes further thread H from the thread guide to complete the formation of the new loop, as shown by the arrow F1.
• the thread H is not free to run as it is tightened by the previous stitch M that is passing over the head of the adjacent needle (the needle number 2) that is in the casting off phase.
• a tension peak therefore occurs in the segment of thread H arranged between the needles number 2 and 3, and the needle number 2 is therefore pulled towards the left in the drawing (as indicated by the arrow FB over it), bends and moves towards a wall of the cylinder channel inside which it is arranged.
• the needle does not work in a position centered in the corresponding channel, and it can come into contact (as in W) with the wall of the channel (or with the sinker, in machines using it), being therefore subjected, with the use, to wear.
• the object of the present invention is to substantially reduce the above described problems and to allow producing particular knitted structures in a simple manner.
• each type of needle being actuated by a different stitch cam track and - for each feed - the stitch cams of one track present at least the lower part of downward movement of the needles offset in the direction of the rotation movement of the cylinder with respect to the corresponding part of the corresponding cams of the other track, so as in each feed to delay by a given angle the downward movement of the needles of one type with respect to the downward movement of the needles of the other type.
• This delay can be in the order of some needle passes, and is chosen according to the fineness of the machine and/or the characteristics of the fabric to be produced in a range of values generally comprised between 2 and 5 needle passes.
• figure 1 shows a perspective view of two types of needle generally used in the circular knitting machines
• figure 2 shows a partial perspective of the control cams for the needles mounted on adequate cam-holders, the set being shown from the side facing the needle cylinder;
• figure 3 shows a perspective view of the needle path in correspondence of a feed, in a circular knitting machine of the known type;
• figure 4 shows an enlarged perspective view of the detail IV of figure
• figure 5 shows a schematic plan view of the detail IV of figure 3;
• figure 6 shows a front view of three cams in an improved machine according to the present invention
• FIGS. 7, 8A and 8B show respective schematic plan views of the needle path in the area of loop formation of a feed with respective different arrangements of the needles in a machine according to the invention
• figure 9 shows a view analogous to that of figure 6 for other types of cams used in the machines according to the present invention.
• figure 10 shows a front view of a cam-holder group of a feed of an improved circular knitting machine according to the present invention, provided with needle control cams for two tracks;
• figures 11 and 12 show a cam-holder group in a side view according to XI-XI of figure 10 and in an exploded view respectively.
• FIG. 6 shows frontally the cams used in a machine according to the invention instead of the traditional cams. More in particular, the cams according to the invention are of different types: cams hereinafter called “cam of type A” (figure 6) define a first track P1 (figure 2) and cams hereinafter called “cams of type R” define the second track P2. In figure 6 a third type of cam is also shown, called “cam of type N", used in the known machines both for the track P1 and for the track P2.
• the needles A1 - provided with butt T1 to follow the track P1 - are therefore guided by "type A” cams and, in each feed, they meet the tip (called “stitch formation tip") of the respective "type A” cam in advance relative to what occurs if they would be guided by a “type N” cam.
• the needles A2 - provided with butt T2 to follow the track P2 - are guided by "type R" cams and, in this feed, they meet the tip of the respective "type R” cam delayed relative to what occurs if they would be guided by a "type N” cam.
• needles A1 in the cylinder channels in odd position needles A1 are inserted with the butt T1 and in the channels in even position needles A2 with the butt T2 are inserted.
• the needles of even position make a path different than that of the needles of odd position as they are guided by respective cam tracks P1 , P2 having different profiles. In this way a situation occurs that is able to prevent the yarn from being tightened on the needle forming a new stitch, thus eliminating the lateral bending of the needles that damages prematurely needles and sinkers, if any.
• Figure 7 represents the loop formation with this "one-to-one" arrangement of needles and with two tracks P1 , P2, of control cams for the needles respectively with “type A” and “type R” cams. It is clearly apparent that the needles A1 with the butt T1 form loop in the point indicated with M1 and the needles A2 with the butt T2 form loop in the point indicated with M2.
• the needle indicated with A1 * in figure 7, engaged in the track P1 and forming the loop in the point M1 is preceded by the needle indicated with A2* engaged in the track P2 and, differently from the common case of figure 5 described above, it is not into contact with the yarn Z being knitted and therefore it does not cause the tightening of the yarn and the bending of the needle A2*.
• the feeding yarn Z is free from obstacles and can be freely pulled by the needle A1 * to form loop without being subjected to a peak of tension in the branch between the needles A1 * and A2* and therefore without bending these needles.
• the needle A2 forming loop in the point M2 is preceded by the needle A1 ** that is going upwards. This latter "releases" yarn to the needle that is in the point M2 thus facilitating it in the loop formation.
• control cams for the needles described above it is possible to use the arrangement of the control cams for the needles described above to make particular knitted fabrics by feeding to the needles two yarns in at least one feed so that - in at least one feed - a yarn is taken only by the needles lowered in advance, whilst the other yarn is taken by all the needles.
• Figure 8A shows a first example of this use of the invention, wherein on the cylinder periphery two types of needles A1 , A2 have been used, distributed mutually alternate according to a so-called "one-to-one" arrangement and at each feed a thread guide G is used with two holes G1 , G2 for the pass of respective yarns X and Y, these holes being adequately arranged so that the descending segment X1 of the yarn X is displaced with respect to the descending segment Y1 of the yarn Y according to the direction F of rotation of the needle cylinder and to an extent so that it cannot be taken by the A1-type needles, that move downwards in advance along the cam track P1 , but only by the needles A2 - that follow the cam track P2 - together with the other yarn Y.
• the needles A2 of the track P2 take both the yarn X and the yarn Y on the respective descending segments X1 , Y1 , the needles A1 - being lowered by cams of the track P1 having the advanced downward movement - take only the yarn Y in the descending segment Y1 and refuse the yarn X, whose descending segment X1 is adequately displaced in the direction of the arrow F.
• the needles of the track P1 in this arrangement cannot take the yarn X but only the yarn Y and all the needles take the yarn Y.
• a fabric is obtained characterized by an optimum elasticity both in longitudinal and transverse direction, with a 30-40% save in elastomer relative to a knitted fabric formed by means of traditional cams working on each feed with two yarns (elastomeric and non-elastic thread).
• a fabric is obtained characterized by a lower weight relative to the fabric produced with elastomer on all the feed and presenting an aspect similar to that of the rib knitting that can be produced only on more complex double needle bed machines.
• Figure 8B shows a different arrangement of the needles in a machine according to the present invention wherein, along the cylinder periphery, now are alternatively inserted pairs of needles A1 with the butt T1 and pairs of needles A2 with the butt T2, in a usually called "two-to-two" configuration.
• the machine is fed at each feed with two respective yarns X, Y passing through respective holes G1 , G2 of a thread guide G.
• the holes G1 and G2 are arranged so that the descending segment X1 of the yarn X is displaced with respect to the descending segment Y1 of the yarn Y according to the direction F of the movement of rotation of the needle cylinder, so that it cannot be taken by the type A1 needles, that move downward in advance along the track P1 , but only by the type A2 needles following the track P2.
• a circular knitting machine according to the present invention can be therefore adapted to perform all the various known knit patterns that can be usually performed on similar machines and containing tuck and/or floated stitches.

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• Engineering & Computer Science (AREA)
• Textile Engineering (AREA)
• Knitting Machines (AREA)

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Applications Claiming Priority (3)

Publications (1)

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Family Applications (1)

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Cited By (1)

Family Cites Families (9)

• 2010
  • 2010-03-09 IT ITFI2010A000031A patent/IT1398722B1/it active
• 2011
  • 2011-02-21 WO PCT/IT2011/000047 patent/WO2011101884A2/en not_active Ceased
  • 2011-02-21 BR BR112012021126A patent/BR112012021126A2/pt not_active Application Discontinuation
  • 2011-02-21 CN CN2011800104293A patent/CN102770591A/zh active Pending
  • 2011-02-21 EP EP11714856A patent/EP2539494A2/de not_active Withdrawn

Non-Patent Citations (1)

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