Abstract:
The linking device ( 9 ) includes a first bowed needle ( 17 ) mounted on a first shaft ( 13 ) and a second bowed needle ( 19 ) mounted on a second shaft ( 15 ). The first shaft ( 13 ) and the second shaft ( 15 ) are mutually inclined to each other and are controlled in order to pivot alternatingly around a pivot axis (A-A) of the first shaft ( 13 ) and a pivot axis (B-B) of the second shaft ( 15 ), respectively. The first shaft ( 13 ) is rigidly coupled to a first pin ( 27 ) pivoting therewith; the second shaft ( 15 ) is rigidly coupled to a second pin ( 31 ) pivoting therewith; and a slider ( 35 ) is slidingly mounted on the first pin ( 27 ) and on the second pin ( 31 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a linking device for sewing or linking edges of fabric, for example for sewing or linking the toes of stockings or other tubular knitted articles. 
       BACKGROUND ART 
       [0002]    In the textile field, and especially in the hosiery and knitting industry, the production is well known of tubular knitted articles, for example stockings, socks and tights, using circular knitting machines. In some cases, the toe of the tubular knitted article shall be closed by linking or sewing. There are circular knitting machines producing tubular knitted articles with closed toe. These machines are however complex and expensive. 
         [0003]    In many cases, the tubular knitted article exits from the circular knitting machine with the open toe, and shall be transferred to a sewing or a linking machine. To this end, there are devices taking the tubular knitted article from the needle cylinder of the circular knitting machine and transferring it to the sewing machine or the linking machine. Examples of this type of devices are disclosed in WO2004/035894, WO2010/086708, US20160024695. 
         [0004]    Usually, the linking devices comprise two bowed needles provided with reciprocating rotary motion for linking by means of two yarns. A critical aspect of these devices is the adjustment of the needle position with respect to the members on which the tubular knitted article is engaged, constituted for example by spikes of a linking machine, or by pick-up hooks that are also used to take the tubular knitted article from the needle cylinder of the circular knitting machine (see US20160024695). 
         [0005]    There is therefore a need for a simpler linking device wherein the adjustment of the needle position is easier. 
       SUMMARY OF THE INVENTION 
       [0006]    According to a first aspect, the invention relates to a linking device comprising a first bowed needle mounted on a first shaft and a second bowed needle mounted on a second shaft. The first shaft and the second shaft are mutually inclined to each other, i.e. they are so arranged that their axes are not parallel to each other. They are controlled in order to pivot reciprocatingly around a pivoting axis of the first shaft and a pivoting axis of the second shaft, respectively. The linking device also comprises a first pin rigidly coupled to the first shaft and pivoting therewith, and a second pin rigidly coupled to the second shaft and pivoting therewith. A slider connects the first pin and the second pin, being slidingly mounted on both the pins. By driving one of the two shafts into reciprocating pivoting motion, for example by means of an electric motor, said one shaft can transfer the motion to the other shaft through the coupling provided by means of the two pins and the slider mounted slidingly on them. 
         [0007]    In this way a particularly simple device is provided, easy to be maintained and adjusted, of limited costs and very efficient and accurate. 
         [0008]    Further advantageous features and embodiments of the linking device will be described below with reference to the drawing, and in the attached claims. 
         [0009]    The first pin may be, for instance, parallel to the first shaft and spaced therefrom. Analogously, the second pin may be parallel to the second shaft and spaced therefrom. 
         [0010]    In advantageous embodiments, the two shafts are oriented at 90° to each other, i.e. their axes are spaced from each other and lie on different planes, but are orthogonal to each other in a plan view. The slider may have two sliding seats, wherein the two pins are slidingly engaged. The two seats may be rigidly connected to each other, i.e. the slider may comprise a single rigid component where the two sliding seats for the pins are provided. The distance between the two seats, i.e. the distance between two parallel axes, containing the axes of the sliding seats, may be equal to the distance between parallel planes containing the pivoting axes of the two shafts. 
         [0011]    For at least one of the two bowed needles, the distance between the respective pin and the pivot shaft can be adjusted. It can also be envisaged to provide this adjustment capability for both the bowed needles. 
         [0012]    In some embodiments, at least one of the bowed needles, and preferably both needles, are adjustable, with respect to a supporting structure, in a direction parallel to the pivoting axis of the respective shaft. 
         [0013]    In practical embodiments, one or both the bowed needles lie in a plane orthogonal to the pivoting axis of the respective shaft. 
         [0014]    According to a further aspect, the invention relates to a linking machine for linking edges of a knitted article comprising engagement members for engaging loops of the knitted article, and a linking device according to the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    A more complete understanding of the illustrated embodiments of the invention and the many advantages achieved will be obtained with reference to the detailed description below in combination with the appended drawings, wherein: 
           [0016]      FIG. 1  shows a side view of the linking device in combination with a support member for supporting the tubular knitted article to be linked; 
           [0017]      FIG. 2  shows a view according to II-II in  FIG. 1 ; 
           [0018]      FIG. 3  shows a view according to in  FIG. 2 ; 
           [0019]      FIG. 4  shows a view according to II in  FIG. 1 , with the needles in a different angular position; 
           [0020]      FIG. 5  shows a view according to V-V in  FIG. 4 ; 
           [0021]      FIG. 6  shows a view analogous to that of  FIG. 5 , with the needles in a different axial position; 
           [0022]      FIG. 6A  shows an axonometric view of the slider connecting the two bowed needles of the linking device; 
           [0023]      FIGS. 7A-7C  show a movement sequence of the linking device; 
           [0024]      FIGS. 8A and 8B  show a front view of an adjustment mechanism for adjusting the distance between one of the needles and the respective pin for the connection to the slider. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0025]    The following detailed description of the exemplary embodiments refers to the accompanying drawings. The same reference numbers in different drawings identify the same or similar elements. Additionally, the drawings are not necessarily drawn to scale. Also, the following detailed description does not limit the invention. Instead, the scope of the invention is defined by the appended claims. 
         [0026]    Reference throughout the specification to “one embodiment” or “an embodiment” or “some embodiments” means that the particular feature, structure or characteristic described in connection with an embodiment is included in at least one embodiment of the subject matter disclosed. Thus, the appearance of the phrase “in one embodiment” or “in an embodiment” or “in some embodiments” in various places throughout the specification is not necessarily referring to the same embodiment(s). Further, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments. 
         [0027]    In  FIGS. 1-5  the linking device is shown in combination with a support system  1  for an article to be linked, for example a sock. Number  3  generically indicates engagement members for engaging the knitted article, not shown, that are part of the support system  1 . The engagement member  3  may comprise hooks  5  and latches  7 . It should be understood that, while in the attached figures only some engagement members  3  have been shown just by way of example, actually a full arc of engagement members may be provided, for example an approximately 180° arc of engagement members. The system  1  with the engagement members  3  may be designed as disclosed for instance in US20160024695. In other embodiments, the system  1  may be constituted by spikes of a linking machine, as described for example in WO2004/035894. 
         [0028]    Reference number  9  indicates the linking device as a whole. It comprises a supporting structure  10 , on which a first shaft  13  and a second shaft  15  are mounted. The first shaft  13  is provided with a pivoting, i.e. reciprocating, angular motion around a pivoting axis A-A, while the second shaft  15  is provided with a pivoting, i.e. reciprocating, angular motion around a pivoting axis B-B. In the illustrated embodiments, the two shafts  13  and  15 , and therefore the two axes A-A and B-B, are directed at 90° with respect to each other, but they lie on two distinct parallel planes arranged at a distance D 3 , as shown in  FIGS. 1 and 8B . 
         [0029]    A first bowed needle  17  is integral with the first shaft  13 , and a second bowed needle  19 , below also called “crochet needle”, is integral with the second shaft  15 . The first bowed needle  17  moves on a plane orthogonal to the axis A-A when the first shaft  13  reciprocatingly pivots around the axis A-A, while the second bowed needle, or crochet needle,  19  moves on a plane orthogonal to the axis B-B when the second shaft  15  reciprocatingly pivots around the axis B-B. 
         [0030]    In the illustrated embodiment, the first bowed needle  17  is integral with the first shaft  13  by means of a first arm  21 , while the second bowed needle  19  is integral with the second shaft  15  by means of a second arm  23  (see also the sequence in  FIGS. 7A-7C ). 
         [0031]    A first yarn Y 1  is fed to the first bowed needle  17 , while a second yarn Y 2  is fed to the second bowed needle  19 . The first bowed needle  17  and the second bowed needle  19  cooperate with each other and with a stationary finger  25 , that may be supported by the supporting structure  10  in a way not shown for the sake of drawing simplicity. 
         [0032]    The pivoting motion of the first bowed needle  17  and of the second bowed needle  19 , cooperating with each other and with the finger  25 , allows to form a series of chain stitches for linking edges of fabric held adjacent to each other by means of the members  3 ,  5 . The way for making the sewing or linking stitches is known to those skilled in the art and does not require to be described herein. The pivoting motion of the first bowed needle  17  is synchronized with the motion of the second bowed needle, or crochet needle,  19 , and these motions are represented in the sequence of  FIGS. 7A-7C . This sequence shows a portion of the sequence of motion of the bowed needles  17 ,  19 , and precisely the sequence when the first bowed needle  17  and the second bowed needle, or crochet needle,  19  pivot from respective positions of maximum lifting ( FIG. 7A ) to respective positions of maximum lowering ( FIG. 7C ). The complete cycle of motion of the bowed needles  17 ,  19  comprises the reverse sequence (from  FIG. 7C  to  FIG. 7A ), when both the bowed needles  17 ,  19  move upwards from the position of maximum lowering to the position of maximum lifting. 
         [0033]    The movement may be imparted by means of an actuator, for example an electronically controlled electric motor, schematically indicated with M only in  FIG. 2 , which can be connected to the second shaft  15  by means of a suitable mechanical transmission, for example by means of a rod-crank system  30 . The rod-crank system  30  changes the continuous rotation motion of the motor M into a reciprocating pivoting motion of the second shaft  15  and of the second bowed needle, or crochet needle,  19  around the axis B-B. The motion is transmitted to the first shaft  13  and to the first bowed needle  17  by means of a mechanism described below. 
         [0034]    In other embodiments, not shown, the motor M may be connected, by means of a suitable mechanical transmission, to the first shaft  13  instead of being connected to the second shaft  15 . 
         [0035]    In order to transmit the motion from one to the other of the two shafts  13 ,  15 , a first pin  27  is integral with the first shaft  13 , the pin being carried by a first auxiliary arm  29 . The first auxiliary arm  29  is rotatingly coupled to the first shaft  13 , i.e. it pivots integrally therewith. The two arms  29  and  21  are angularly spaced from each other. In the illustrated embodiment, the first pin  27  is parallel to the first shaft  13 . 
         [0036]    A second pin  31  is integral with the second shaft  15 . The second pin may be carried by a second auxiliary arm  33 , rotatingly constrained with the second shaft  15 , i.e. the second pin  31  pivots integrally with the second shaft  15 . The second auxiliary arm  33  is angularly spaced from the second arm  23  constraining the second bowed needle  19  to the second shaft  15 . The second pin  31  is parallel to the second shaft  15 . 
         [0037]    The first pin  27  and the second pin  31  are mechanically coupled to each other by means of a slider  35 . The slider  35  may comprise two sliding seats  36 ,  38  ( FIG. 6A ), oriented at 90° with respect to each other but lying on two distinct planes. The first pin  27  is inserted in the sliding seat  36 , while the second pin  31  is inserted in the seat  38 . The distance between two parallel planes containing the axes of the sliding seats (and therefore the axes of the first pin  27  and of the second pin  31 ) is indicated with D 4  in  FIGS. 2 and 8B . 
         [0038]    Advantageously, the distance D 4  between the parallel planes containing the axis of the first pin  27  and the axis of the second pin  31 , corresponding to the distance between the axis of the seats  36  and the axis of the seat  38 , is equal to the distance D 3  between the parallel planes containing the pivoting axis A-A of the first shaft  13  and the pivoting axis B-B of the second shaft  15 . In this way, the two bowed needles  17  and  19  perform the same movements. 
         [0039]    As it is clearly apparent from the sequence of  FIGS. 7A-7C , when the second shaft  15  is driven into reciprocating pivoting motion according to the arrow f 15  by means of the motor M, the reciprocating pivoting motion is transmitted to the first shaft  13 , and thus to the first bowed needle  17 , through the pins  31  and  27  and through the slider  35 . During the motion, each of the two pins  27 ,  31  slides and pivots in the respective seat provided in the slider  35 , and the slider is substantially moved by means of the pins  27 ,  31  to which it is constrained. 
         [0040]    Thanks to this mechanical transmission between the two bowed needles  17  and  19 , provided by means of the slider  35  and of the pins  27 ,  31 , it is possible to have a simpler adjustment of the position of each bowed needle  17 ,  19  with respect to the supporting structure  10 , and therefore with respect to the system  1 , independently of the other bowed needle. For example, it is possible to adjust the position of the first bowed needle  17  parallel to the axis A-A without changing the position of the second bowed needle  19 . Similarly, the axial position of the second bowed needle  19  parallel to the axis B-B may be adjusted independently of the first bowed needle  17 . 
         [0041]    The possibility of adjusting the position of the bowed needles  17 ,  19  with respect to the reciprocating pivoting axis A-A and to the reciprocating pivoting axis 
         [0042]    B-B is shown in detail in  FIGS. 5 and 6 . In  FIGS. 5 and 6 , each of the two bowed needles  17 ,  19  is shown in two different axial positions. The adjustment of the position of the bowed needles  17  is performed according to the arrow fA, while the adjustment of the position of the bowed needle  19  is performed according to the arrow fB, in each case in a direction parallel to the respective pivoting axis A-A and B-B. 
         [0043]    An adjustment arrangement may be provided for independently adjusting the position of each bowed needle  17 ,  19  in the direction of the axis A-A and of the axis B-B respectively.  FIGS. 5 and 6  show a possible embodiment of this adjustment arrangement. The first shaft  13  may be pivotingly supported in a first sleeve  41  housed in the supporting structure  10 . The first sleeve  41  has a helical groove  43  where a fastening screw engages. By tightening the fastening screw  45 , the first sleeve  41  is axially and torsionally blocked in the supporting structure  10 . By loosening the fastening screw  45 , it is possible to rotate the first sleeve  41  around the axis A-A. As the fastening screw  45  remains engaged in the helical groove  43 , the rotation of the first sleeve  41  around the axis A-A causes a corresponding axial movement of the first sleeve  41  according to the arrow fA in the housing seat of the supporting structure  10 . As the first shaft  13  is rotatable supported in the first sleeve  41 , but it is axially blocked with respect thereto, the translation of the first sleeve  41  according to fA causes a corresponding translation of the first shaft  13  and of the first bowed needle  17  according to the arrow fA. 
         [0044]    The adjustment of the position of the first bowed needle  17  according to the direction of the axis A-A is performed as follows: the fastening screw  45  is loosed, while keeping it engaged in the helical groove  43 . The first sleeve  41  rotates around the axis A-A until the first bowed needle  17  achieves the desired position, and lastly the fastening screw  45  is tightening again until the first sleeve  41  is blocked in the selected axial position. 
         [0045]    The adjustment of the position of the second bowed needle, or crochet needle,  19  in the direction of the axis B-B is performed with substantially the same arrangement. To this end, a second sleeve  47  is provided, housed in a seat of the supporting structure  10  and provided with a helical groove  49 . A fastening screw  51  engages the helical groove  49 . The adjustment of the position of the second bowed needle  19  according to the arrow fB is performed similarly to what has been already described with reference to the first bowed needle  17 . 
         [0046]    In some embodiments, a further adjustment possibility may be provided for the linking device  9 . This further adjustment possibility is clearly shown in  FIGS. 8A and 8B , showing a view of the two bowed needles  17 ,  19 , of the respective shafts  13 ,  15 , of the slider  35  and of the pins  27 ,  31 , according to the axis A-A. In  FIGS. 8A and 8B  the supporting structure  10  and the sleeves  41  and  47  have been omitted. 
         [0047]    As it is shown in  FIGS. 8A and 8B , the distance between the first pin  27  and the axis A-A of the first shaft  13  is adjustable. This distance is indicated with D 1  in  FIG. 8A  and with D 2  in  FIG. 8B , wherein D 1  is shorter than D 2 . In order to adjust the distance between the first pin  27  and the axis A-A of the first shaft  13 , it is possible to block the first pin  27 , and the first auxiliary arm  29  carrying it, by means of a plate  53  fastened to the head of the first shaft  13  through fastening screws  55 . By loosening the fastening screws  55  the position of the first auxiliary arm  29 , and therefore the distance of the first pin  27 ,can be adjusted with respect to the axis A-A. Once the required distance between the first pin  27  and the axis A-A has been achieved, the fastening screws  55  may be tightened again. 
         [0048]    In order to simplify the adjustment, an adjustment screw  57  and a pre-load spring  59  may be provided. The pre-load spring  59  pushes the first auxiliary arm  28  towards the position of minimum distance of the first pin  27  with respect to the axis A-A. Through the adjustment screw  57  the position of the pin  27  with respect to the axis A-A can be adjusted by pressing or releasing the pre-load spring  59 , as it is visible by comparing  FIGS. 8A and 8B . This adjustment allows to modify the pivoting angle of one bowed needle with respect to the other bowed needle. 
         [0049]    Also the distance between the second pin  31  and the axis B-B can be adjusted, in combination with or as an alternative to the adjustment of the distance between the first pin  27  and the axis A-A.