Patent Publication Number: US-6220061-B1

Title: Slider for double-cylinder circular knitting machines

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a slider for double-cylinder circular knitting machines, particularly for hosiery knitting. 
     It is known that double-cylinder circular hosiery knitting machines generally comprise a lower needle cylinder and an upper needle cylinder which are mutually coaxial and can be actuated rigidly together with a rotary motion about their common axis. 
     In the skirt or curved surface of the lower needle cylinder and in the skirt or curved surface of the upper needle cylinder a plurality of axial slots are provided. The axial slots of the upper needle cylinder are aligned with the slots formed in the curved surface of the lower needle cylinder. Each one of the axial slots of the lower needle cylinder generally accommodates, starting from below, a selector and a slider, whereas each one of the axial slots of the upper needle cylinder accommodates a slider. Between the two needle cylinders, i.e., in the knitting region, in each one of the axial slots there is a needle which has two tips, respectively an upper tip and a lower tip; depending on whether plain stitches or purl stitches are to be produced, said needle is moved into the lower needle cylinder so that it knits with its upper tip or into the lower needle cylinder so that it knits with its lower tip. 
     Since the needle does not have a heel, it is actuated by means of the slider located in the lower needle cylinder or by means of the slider arranged in the upper needle cylinder depending on whether it is meant to form plain or purl stitches. 
     The sliders currently used in double-cylinder circular hosiery knitting machines are generally constituted by an elongated laminar body which has a first longitudinal side which is meant to rest on the bottom of the axial slot formed in the curved surface of the lower needle cylinder or in the curved surface of the upper needle cylinder. 
     Said sliders are further provided with two heels which are mutually spaced along the longitudinal extension of the slider and protrude transversely from a second longitudinal side of the slider which lies opposite the first side. 
     Said heels are used to move the slider along the corresponding axial slot of the lower needle cylinder or upper needle cylinder, so as to produce the actuation of the needle that is associated with said slider in the various knitting processes of the machine. 
     The slider furthermore has on its first longitudinal side, i.e., on its side directed toward the bottom of the axial slot inside which it is accommodated, a hook which engages the lower or upper tip of the needle, depending on whether the slider is in the lower needle cylinder or in the upper needle cylinder. 
     A plurality of cams are arranged around the curved surface of the lower needle cylinder and around the curved surface of the upper needle cylinder and form a series of paths with which the heels of the sliders engage when the needle cylinders are actuated so as to rotate about their axis with respect to said cams. The paths formed by the cams are shaped so as to produce the movement of the sliders along the axial slots of the needle cylinders in which they are accommodated and accordingly produce the actuation of the needles associated therewith. 
     In currently commercially available double-cylinder circular hosiery knitting machines, many of the cams that determine the paths for the heels of the sliders are provided so that they can move in a radial direction with respect to the needle cylinders, so that they can be transferred from an active position, in which they are close to the needle cylinders so that they can be engaged by the heels of the sliders, to an inactive position, in which they are spaced from the needle cylinders so as to avoid interfering with the heels of the sliders, or viceversa, so as to allow to produce different kinds of knitting. 
     The presence of these movable cams, which is required in order to perform the different kinds of knitting, entails the problem that it considerably increases the complexity of the structure of the entire machine. 
     Furthermore, the presence of these movable cams forces the provision, on board the machine, of a specific actuation program which intervenes if an accidental stoppage of the machine occurs due to a power failure; said program restores the correct position of the movable cams before knitting resumes, because if the machine were to restart without first restoring the correct position of the movable cams, the heels of the sliders might break. 
     In practice, the presence of these movable cams makes it necessary to provide the machine with electronic programs which store the position of the movable cams when the power failure occurred, and this constitutes a further complication in the execution of the machine. 
     SUMMARY OF THE INVENTION 
     The aim of the present invention is to solve the above problems, providing a slider for double-cylinder circular hosiery knitting machines which allows to significantly reduce the number of movable cams required for its actuation. 
     Within the scope of this aim, an object of the invention is to provide a slider which allows to considerably simplify the set of cams required for its actuation. 
     Another object of the invention is to provide a slider which, despite a simplification of the cams required for its actuation, nonetheless allows to perform the usual knitting processes that are possible in conventional types of double-cylinder circular hosiery knitting machine. 
     This aim, these objects and others which will become apparent hereinafter are achieved by a slider for double-cylinder circular hosiery knitting machines, comprising an elongated laminar body which has a first longitudinal side which is meant to be rested on the bottom of an axial slot formed in the curved surface of the lower needle cylinder or in the curved surface of the upper needle cylinder and at least two heels which protrude transversely to the longitudinal extension of said laminar body on a second longitudinal side of the laminar body which lies opposite said first side; said laminar body having, proximate to one of its longitudinal ends, means for engagement with a needle, characterized in that a first one of said two heels is arranged on a portion of said laminar body which can move with respect to the remaining part of said laminar body in a direction which has a component which is transverse with respect to the longitudinal extension of said laminar body for the transfer of said first heel from an inactive position to an active position, or viceversa; said first heel being spaced from said first side more in said active position than in said inactive position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further characteristics and advantages of the present invention will become apparent from the following detailed description of two preferred but not exclusive embodiments of the slider according to the invention, illustrated only by way of non-imitative example in the accompanying drawings, wherein: 
     FIG. 1 is a view of the slider according to the invention, in the first embodiment, with the first heel in the active position and inserted in the lower needle cylinder; 
     FIG. 2 is a view of the slider according to the invention in the first embodiment, with the first heel in the inactive position and inserted in the lower needle cylinder; 
     FIG. 3 is a view of the slider according to the invention in the second embodiment, with the first heel in the active position and inserted in the lower needle cylinder; 
     FIG. 4 is a view of the slider according to the invention in the second embodiment, with the first heel in the inactive position and inserted in the lower needle cylinder; 
     FIG. 5 is a schematic view, projected onto a plane, of the set of slider actuation cams in the second embodiment, illustrating the path of the heels of the slider when the corresponding needle must be prevented from knitting; 
     FIG. 6 is a schematic view, projected onto a plane, of the set of slider actuation cams in the second embodiment, illustrating the path of the heels of the slider during the transfer of the corresponding needle from the lower needle cylinder to the upper needle cylinder; 
     FIG. 7 is a schematic view, projected onto a plane, of the set of slider actuation cams in the second embodiment, illustrating the path of the heels of the slider in the actuation of the corresponding needle for producing drop stitches at two feeds of the machine. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to FIGS. 1 and 2, the slider according to the invention, in the first embodiment, generally designated by the reference numeral  1 , comprises an elongated laminar body  2  which has a first longitudinal side  3 , meant to rest on the bottom  80   a  of the axial slot  80  of the needle cylinder  81  in which it is inserted, and a second longitudinal side  4 , which lies opposite with respect to the first longitudinal side  3 . 
     The slider is provided with a first heel  5  and with a second heel  6  which are mutually spaced along the longitudinal extension of the laminar body  2  and run transversely to the longitudinal extension of the laminar body  2  on the second side  4 . 
     According to the invention, the first heel  5  is arranged on a portion of the laminar body  2  which can move with respect to the remaining part of the laminar body  2  in a direction which has a component which is transverse with respect to the longitudinal extension of the laminar body in order to allow the transfer of the first heel  5  from an inactive position to an active position or viceversa. In the active position, the first heel  5  is spaced from the first side  3  of the laminar body  2  more than in the inactive position. 
     Proximate to one of its longitudinal ends, the laminar body  2  is provided, on its first longitudinal side  3 , with means  7  for engaging the needle  8  that is located in the same slot  80  of the lower or upper needle cylinder  81 . 
     Said engagement means  7  are constituted by a hook which is provided at a suitable seat  3 a which is formed starting from a longitudinal end of the laminar body  2  and in which it is possible to accommodate the lower or upper portion of the needle  8  depending on whether the slider is in the lower needle cylinder or in the upper needle cylinder. 
     The first heel  5  is preferably constituted by the heel that lies closest to the longitudinal end of the laminar body  2  which can engage the needle  8 . 
     In the first embodiment, shown in FIGS. 1 and 2, the first heel  5  is associated, preferably monolithically, with a portion  9  of the laminar body  2  which can flex elastically on the plane of arrangement of the laminar body  2  with respect to the remaining part of the laminar body  2 . 
     More particularly, the portion  9  is preferably formed monolithically with the remaining part of the laminar body  2  and extends from it starting from a region which is proximate to the longitudinal end of the laminar body  2  that lies opposite with respect to the end of said body that can engage the needle  8 . 
     The second heel  6 , located proximate to the longitudinal end of the laminar body  2  that lies opposite the end that can engage the needle  8 , is preferably rigidly coupled to the remaining part of the laminar body  2 . 
     The portion  9  has, on the opposite side with respect to the first heel  5 , a resting region  10  which can be engaged against the remaining part of the laminar body  2  in the flexing of the portion  9 , so as to delimit the movement of the first heel  5  transversely to the longitudinal extension of the laminar body  2  in its transfer from the active position to the inactive position, as shown in particular in FIG.  2 . 
     The slider according to the invention, in the second embodiment, shown in particular in FIGS. 3 and 4 and generally designated by the reference numeral  11 , also comprises an elongated laminar body  12  which has a first longitudinal side  13  which is meant to rest against the bottom  80   a  of the axial slot  80  of the lower or upper needle cylinder  81 , in which it is to be accommodated, and a second longitudinal side  14  which lies opposite the first longitudinal side  13 . 
     In this embodiment also, the slider  11  is provided, proximate to one of its longitudinal ends, with means  17  for engagement with a needle  8 . 
     Said engagement means  17  are constituted, as in the first embodiment, by a hook which can engage the lower or upper tip of the needle  8  and is formed in a suitable seat  13 a which is provided on the side  13  of the laminar body  12  starting from its longitudinal end which is meant to be directed toward the needle  8 . The seat  13 a is meant to receive the lower portion or the upper portion of the needle  8 , depending on whether the slider is accommodated in the lower needle cylinder or in the upper needle cylinder. 
     The laminar body  12  is provided with a first heel  15  and with a second heel  16  which run transversely to the longitudinal extension of the laminar body  2  on the second longitudinal side  14 . 
     The second heel  16 , located proximate to the longitudinal end of the laminar body  12  that lies opposite the end that can engage the needle  8 , is preferably rigidly coupled to the remaining part of the laminar body  12 . 
     In this embodiment, the first heel  15  is fitted on a portion  19  which can oscillate with respect to the remaining part of the laminar body  12  in order to allow the transfer of the first heel  15  from an inactive position, in which it is close to the second side  13 , to an active position, in which it is further spaced from the first longitudinal side  13  than in the inactive position, or viceversa. 
     Preferably, in this embodiment also the first heel  15  of the two heels  15  and  16 , is the one nearest to the end of the laminar body  12  that can engage the needle  8 . 
     The oscillating portion  19  is pivoted to the remaining part of the laminar body  12  at an intermediate portion. The pivoting can be achieved, as shown, by means of a particular geometric configuration of the sides of the portion  19  and of the remaining part of the laminar body  12  which are in mutual contact. 
     The first heel  15  is located proximate to the end of the oscillating portion  19  that lies closest to the end of the laminar body  12  that can engage the needle  8 , and proximate to the other end of the oscillating portion  19 , which lies proximate to the second heel  16 , an actuation lug  20  is provided which can be contacted to produce the oscillation of the oscillating portion  19  in the transfer of the first heel  15  from the inactive position to the active position, as will become apparent hereinafter. 
     The laminar body  12  of the slider, in the second embodiment, is provided with means for delimiting the oscillation angle of the oscillating portion  19  with respect to the remaining part of the laminar body  12 . 
     Said delimiting means comprise a seat  21  which is formed on the second longitudinal side  14  of the laminar body  12 ; the oscillating portion  19  is arranged in said seat  21 . The seat  21  is delimited, along a direction which is parallel to the longitudinal extension of the laminar body  12 , by two sides located proximate to the ends of the oscillating portion  19 . On these two sides there are shoulders  22  and  23  which are engaged respectively by one end of the oscillating portion  19  when the heel  15  is moved into the active position and by the other end of the oscillating portion  19  when the first heel  15  is moved into the inactive position, thus limiting the breadth of the oscillation allowed to the oscillating portion  19 . 
     In the first embodiment and in the second embodiment, when the first heel  15  is in the active position it protrudes from the slot  80  of the needle cylinder  81  and can engage at least some of the slider actuation cams that surround the needle cylinder and will be described in greater detail hereinafter, whereas when it is in the inactive position it is recessed in the slot  80  of the needle cylinder so as to avoid engaging said cams. 
     When the first heel  15  is in the active position, the actuation lug  20  is located inside the slot  80 , whereas when the first heel  15  is in the inactive position said lug protrudes from the slot  80  and can engage at least some of the slider actuation cams that face the needle cylinder and will be described in greater detail hereinafter. 
     The operation of the slider according to the invention is now described with reference to FIGS. 5,  6  and  7 , which illustrate, merely by way of example, a possible configuration of the slider actuation cam set as regards the lower needle cylinder  81 . 
     As shown in these figures, the cams comprise a fixed upper cam  30  which has, along its lower edge, regions designated by the reference numerals  31  to  36  which are shaped like an inclined plane and can be contacted by the first heel  15 . Said regions  31 - 36  produce the transfer of said heel  15  from the active position to the inactive position or allow its transfer from the inactive position to the active position. 
     The actuation cams for the first heel  15  further comprise a first lifting cam  37 , two mutually opposite lowering cams, designated by the reference numerals  38  and  39  respectively, which are provided at a first feed or drop of the machine, and a lowering cam  40 , which is provided at a second feed or drop of the machine. The actuation cams for the first heel  15  are completed by two lifting cams  41  and  42  which are arranged consecutively with respect to each other at the feed or drop proximate to the lowering cam  40 . 
     The actuation cams for the second heel  16  comprise a fixed cam  50  which runs entirely around the needle cylinder and further cams which are designated by the reference numerals  51  to  54 . 
     In addition to the cams, around the needle cylinders there are suitable guiding elements which are arranged at a level which is adapted to make contact with the actuation lug  20  in order to produce the oscillation of the oscillating portion  19  and therefore produce the transfer of the first heel  15  from the inactive position to the active position. In FIGS. 5,  6  and  7 , said guiding element have been designated by the reference numerals  71 ,  72 ,  73  and  74 . 
     In FIGS. 5,  6  and  7 , the first heel  15  is represented by a rectangle which is black when the first heel  15  is in the active position and is instead white when said heel  15  is in the inactive position. The same rule has been adopted for the actuation lug  20 , which is represented by a black rectangle when it protrudes from the needle cylinder and by a white rectangle when it is instead recessed in the slot  80  of the needle cylinder. 
     FIG. 5 illustrates the path followed by the heels  15  and  16  and by the actuation lug  20  of the slider  11  when the corresponding needle  8  must be excluded from knitting at the two feeds of the machine; the movement of the slider  11  with respect to the set of cams for its actuation is designated by the arrow  60 . 
     In this operating condition, the first heel  15  is in the inactive position. In this condition, the slider  11  is not moved along the corresponding slot  80  of the needle cylinder  81  in which it is inserted and the first heel  15  can move without interference beyond the cams  37 ,  38 ,  39 ,  41 ,  42  and  40  since it is in the inactive position. 
     It should be observed that due to this fact the cam  38 , which can usually move in a radial direction with respect to the needle cylinder, can be provided as a fixed cam and the lowering cams  39  and  40  also can be provided as fixed cams except, of course, for the possibility to move said cams, in a per se known manner, in a direction which is parallel to the axis of the needle cylinders in order to allow to vary the length of the loops of knitting. 
     It should also be observed that directly ahead of the cam  40  and of the cam  39  in the direction  60  is not necessary to provide lowering cams in order to move the first heel  15  below the lower edge of said lowering cams  39  and  40 , as instead required by conventional machines, wherein the presence of said lowering cams applies unwanted stress to any loops of knitting engaged by the needle  8  associated with the slider. In the transfer of the needle from the lower cylinder to the upper cylinder, shown in FIG. 6, in which the direction of the movement of the slider with respect to the cams has been indicated by the arrow  61 , the first heel  15  is initially, i.e., starting from the right side of FIG. 6, in the active position. The slider is lifted by other elements, constituted for example by selectors which are present in the same slot  80  below said slider, and is then lowered by the cam  30 . 
     The slider is then raised by means of the selector or of other underlying elements and the first heel  15  engages the inclined-plane region  31  of the cam  30  that produces the transfer of the heel  16  from the active position to the inactive position. In this position, the slider, by means of other cams of a known type which are not described further for the sake of simplicity, disengages with its hook  7  from the lower tip of the needle which is engaged by the slider arranged in the upper cylinder. Then the actuation lug  20  engages against the guiding element  72 , which produces the transfer of the first heel to the active position. The first heel  15  then engages a descending portion of the cam  30  which produces the lowering of the slider. The first heel  15  engages the portion  34  of the cam  30  that returns the first heel  15  to the inactive position. Said FIG. 6 illustrates the further lifting of the slider in the lower cylinder, directly ahead of the feed served by the lowering cam  40 , in the direction indicated by the arrow  61 , in order to open the tab of the needle that has been transferred into the upper needle cylinder. After this further lifting, the actuation lug  20  is contacted by the guiding element  74 , which again causes the transfer of the first heel  15  into the active position, so that by engaging another descending portion of the cam  30  it produces the lowering of the slider. 
     FIG. 7 illustrates the path of the heels of the slider during the production of drop stitches with the needle associated therewith at the two feeds of the machine. 
     Ahead of the feed proximate to which the lowering cams  38  and  39  are provided, along the direction of motion of the slider with respect to the cams, designated by the arrow  62 , the slider is lifted by the corresponding selector or other underlying element, whereas the first heel  15  is in the inactive position due to the contact of said heel with the cam  37 . 
     As a consequence of the engagement of the actuation lug  20  with the cam  54 , the first heel  15  is moved into the active position and, after the needle associated with the slider has engaged the thread at the feed being considered, the first heel  15  engages the lowering cam  39 , which produces the lowering of the slider and therefore the retraction of the associated needle  8  into the lower needle cylinder in order to form new loops, lowering the previously formed loops. 
     The slider is then lifted again by the selector or other underlying element and is moved to a level which allows the needle  8  associated therewith to engage the thread at the next feed. Due to this lifting, the previously formed loops are lowered onto the shank of the needle. 
     Then the first heel  15 , which is still in the active position, engages the lowering cam  40 , which forms new loops and lowers the previously formed loops. 
     Downstream of the feed served by the lowering cam  40 , the first heel  15  again engages the cam  37 , which produces the transfer of the first heel  15  into the inactive position, and the cycle resumes as already described. 
     It should be observed that in this knitting process also the first heel  15  passes without any problem beyond the lowering cam  38 , since said heel  15  is in the inactive position. 
     Although the operation of the slider according to the invention has been described with reference to its use in the lower needle cylinder of a two-feed machine, it is understood that the slider according to the invention can also be used in the upper needle cylinder and in machines having a different number of feeds. 
     In practice it has been observed that the slider according to the invention fully achieves the intended aim, since it allows to considerably simplify the slider actuation cams and to significantly reduce the number of cams that can move in a radial direction with respect to the needle cylinders. 
     The slider thus conceived is susceptible of numerous modifications and variations, all of which are within the scope of the inventive concept; all the details may also be replaced with other technically equivalent elements. 
     In practice, the materials employed, as well as the dimensions, may be any according to requirements and to the state of the art. 
     The disclosures in Italian Patent Application No. MI98A002645 from which this application claims priority are incorporated herein by reference.