Patent Publication Number: US-11384454-B2

Title: Drawing and spinning apparatus and method of mixed yarns for air spinning machines with multiple feeds

Description:
FIELD OF APPLICATION 
     The present invention relates to an apparatus and a method for drawing and spinning mixed yarns for air spinning machines, for example of the air-jet type, with multiple feeds. 
     BACKGROUND OF THE INVENTION 
     As is known, air-jet spinning apparatuses produce the yarn production starting from a single fibre web. The specific area of development of the present invention is that of the yarns obtained from several fibre webs which can be of different materials, of different colours (mélange), of different quality or even of the same material. These multiple feed belts must be appropriately stretched and mixed so as to produce a yarn with the desired features, in a controllable and repeatable manner. 
     To date, the process for obtaining yarns starting from multiple webs (double web) with different colouring or material has some drawbacks and limitations. 
     In fact, there are often barring phenomena which consist in the creation of grooves or strips which can typically be due to irregularities in the yarn count or twist. 
     In summary, typically the bars are due to incorrect couplings, irregular tensions and irregular twists between threads/fibres. 
     In the case of use of double webs in the feed of air spinning apparatuses, in order to limit this defect, it is known, by the same applicant, to carry out the complete separation of the path of the two webs, in such a way as to keep them separated until entry to the introducer nozzle. This separation is also, and mainly, used in order to strengthen the mechanical properties of the thread. 
     In any case, the mere separation of the webs is not sufficient to solve the problem of the bars in the event that one tries to obtain mixed yarns by means of air spinning machines. 
     Furthermore, the ‘extreme’ separation of the webs so as to separate the fibres up to the direct exposure to the air flows in the chamber, if on the one hand limits the phenomenon of the bars, on the other it introduces problems on the colorimetric yield of the final yarn. 
     For example, taking as a reference a melange made with 50% of black tape and 50% of white tape in a known type of apparatus, depending on the side of insertion of the black tape (right or left) the colorimetry of the final yarn is different, that is darker or lighter. 
     Obviously, the variability of the result as a function of the direction of insertion of the yarns constitutes a further complication in the setup of the machine because it would require greater attention in laying the webs being fed. 
     In summary, these bars can occur not only when two different coloured webs are used, but also when using webs of the same colour, of the same material and of mixed material (for example cotton/polyester or viscose/polyester). In other words, the problem of the bars and of the non-uniformity of the colour can occur every time at least two webs are used, even equal to each other, due to the possible non-uniformities that occur at the moment of joining the same webs in the spinning chamber. 
     The need of solving the drawbacks and limitations mentioned with reference to the prior art is therefore felt. 
     BRIEF SUMMARY OF THE INVENTION 
     Such a need is met by a drawing and spinning apparatus of mixed yarns for air spinning machines with multiple feeds according to the invention as disclosed and described herein and by a drawing apparatus for air-spinning machines according to the invention as disclosed and described herein. 
     According to one embodiment, the invention comprises a drawing and spinning apparatus of mixed yarns for air spinning machines with multiple feeds. The drawing and spinning apparatus comprises at least a first and a second introducer element, independent of each other, so as to be able to feed simultaneously at least two separate webs of textile fibre. The drawing and spinning apparatus comprises an air spinning device suitable to spin said webs of textile fibre and an air spinning device chamber for interweaving said webs of textile fibres. The drawing and spinning apparatus comprises an introducer nozzle shaped to receive the webs from a drawing device, placed between the introducer nozzle and the air spinning device, inside respective insertion channels and to introduce the webs inside the spinning chamber in a longitudinal feed direction. In one embodiment, the spinning chamber comprises a plurality of jets of air oriented in a direction substantially tangential to the webs in input to the spinning chamber, so as to interweave the webs and obtain a single yarn in output from the spinning chamber. With respect to a cross-section plane perpendicular to the longitudinal feed direction, in one embodiment, groove bottoms of each of the two insertion channels of the webs into the spinning chamber are aligned along a segment which is offset by an eccentricity with respect to a geometric centre of the spinning chamber, through which a symmetry axis of the spinning chamber passes, the eccentricity being less than 5% of a maximum diameter of the spinning chamber. In a further embodiment, with respect to a cross-section plane perpendicular to the longitudinal feed direction, the cross-section of the insertion channels, at the spinning chamber, has a triangular profile converging and rounded at the groove bottoms. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       Further features and advantages of the present invention will appear more clearly from the following description of preferred non-limiting embodiments thereof, in which: 
         FIGS. 1-2  show a perspective view and a side view of a drawing apparatus for air-spinning machines for mixed yarns, according to an embodiment of the present invention; 
         FIG. 3  shows a schematic view of the introducer nozzle at the inlet section of the spinning chamber; 
         FIGS. 4-5  show perspective views, from the inlet side and from the outlet side, of an introducer nozzle according to a possible embodiment of the present invention; 
         FIGS. 6-7  show perspective views, from the inlet side and from the outlet side, of an introducer nozzle according to a further possible embodiment of the present invention; 
         FIGS. 8-9  show perspective views, from the inlet side and from the outlet side, of an introducer nozzle according to a further possible embodiment of the present invention; 
         FIG. 10  shows a perspective view of an introducer nozzle according to a further possible embodiment of the present invention; 
         FIGS. 11-13  show perspective views of dual channel condensers according to possible embodiments of the present invention. 
     
    
    
     Elements or parts of elements in common to the embodiments described below are referred to with the same reference numerals. 
     DETAILED DESCRIPTION OF THE INVENTION 
     With reference to the aforesaid figures, reference numeral  4  indicates a drawing and spinning apparatus for air spinning machines with multiple feeds. 
     Said apparatus  4  comprises at least a first and a second introducer element  8 ,  12 , independent of each other, so as to be able to feed simultaneously at least two webs N 1 , N 2  of textile fibre. Said webs of textile fibres N 1 , N 2  can be either equal to each other or different in quality, thread count, colour and/or material. 
     The apparatus  4  further comprises an air spinning device  16 , fed with said webs of textile fibres N 1 , N 2 , suitable for producing yarn of certain features. 
     The apparatus  4  further comprises a drawing device  20 , interposed between the introducer elements  8 ,  12  and the air spinning device  16 , comprising a plurality of pairs of drawing cylinders  24 . 
     According to one embodiment, said pairs of drawing cylinders  24  comprise at least one drive cylinder  28  per pair  24 , said drawing cylinders being suitable for progressively drawing each web N 1 , N 2  simultaneously intercepted thereby, in a known manner. 
     By drive cylinder  28  it is meant a cylinder operatively connected to drive means, typically electric motors; usually each drive cylinder  28  faces an idler cylinder  32  which presses on the webs N 1 , N 2  with a suitable pressure and is set in motion by the drive cylinder  32  coupled thereto. 
     According to one embodiment, at least one drive cylinder  28  of a pair of said drawing cylinders  24  of the spinning apparatus  4  is mechanically split into a first drive cylinder which intercepts the first belt N 1  and in a second drive cylinder which intercepts the second ribbon N 2 . 
     Said first and second drive cylinders are operatively connected to distinct drive means so as to be able to be operated at different speeds of rotation, to effect different degrees of drawing of the two webs N 1 , N 2  intercepted by the first and second drive cylinders. 
     Preferably, the drawing device  4  comprises a plurality of pairs of drawing cylinders  24 , in series with each other, suitable for progressively drawing each web N 1 , N 2  simultaneously intercepted by them. 
     Preferably, the webs N 1 , N 2  are fed according to a longitudinal feeding direction L, the introducer elements  8 ,  12  are placed side by side along a transverse direction Z, perpendicular to said longitudinal feeding direction L. 
     It should be noted that the longitudinal direction L is typically inclined with respect to a vertical direction Y, perpendicular to a horizontal direction X, parallel to a bearing plane of the spinning apparatus  4 . 
     The first and second drive cylinders  36 ′,  36 ″ are aligned with each other parallel to said transverse direction Z and rotate around transversal axes of rotation, parallel to the transverse direction Z. 
     The number of pairs of drawing cylinders  24  can be varied according to the total drawing ratio to be obtained and is not binding for the purposes of the present invention. 
     The air spinning device  16  comprises a spinning chamber  40  comprises a plurality of jets of air  44 ,  48  oriented in a direction substantially tangential to the same webs N 1 , N 2  in input to the spinning chamber  40  itself, so as to interweave said webs N 1 , N 2  and obtain a single yarn F in output from the air spinning chamber  20 . 
     Preferably, said air jets  44 , 48  are directed both in a tangential direction towards the centre C of the spinning chamber  40 , so as to synergically trigger the torsion of the fibres of the webs N 1 , N 2  according to a concordant direction. In other words, the two air jets  44 ,  48  are arranged and oriented so as to trigger both an hourly or anticlockwise twist on the fibres. 
     The drawing and spinning apparatus  4  further comprises an introducer nozzle  52  designed to receive the webs N 1 , N 2  from the drawing device  20  in respective insertion channels and introduce the webs N 1 , N 2  inside the spinning chamber  40  according to the longitudinal feeding direction L. 
     Advantageously, with respect to a cross-section plane perpendicular to said longitudinal feed direction L, groove bottoms  60  of each of said two insertion channels  56  of the webs N 1 , N 2  into the spinning chamber  40  are aligned along a segment S which is offset by an eccentricity e with respect to a geometric centre C of the spinning chamber  40 , through which a symmetry axis of the chamber itself  40  passes. 
     It should be noted that the groove bottoms  60  are to be considered at the outlet section of the webs N 1 , N 2  from the introducer nozzle  52 . 
     Said eccentricity e is less than 5% of a maximum diameter D of the spinning chamber  40 . 
     Preferably, in absolute terms, said eccentricity e is less than 0.2 mm. 
     According to a preferred embodiment, said eccentricity e is equal to 0, so that the groove bottoms  60  of the insertion channels  56  of the webs N 1 , N 2  into the spinning chamber  40  and the geometric centre C of the spinning chamber  40  are aligned with each other. 
     According to an embodiment, a radial distance f between the geometric centre C of the spinning chamber  40  and each groove bottom  60  is equal, so that said groove bottoms  60  are equidistant with respect to said geometric centre C. 
     Preferably, said radial distance f is less than 2% of the maximum diameter D of the spinning chamber  40 . 
     Preferably, the radial distance f is such that each of said groove bottoms  60  is tangentially aligned with the corresponding air jet  44 ,  48 . 
     According to a possible embodiment, the insertion channels  56  of the webs N 1 , N 2  in the spinning chamber  40  are at least partially twisted with respect to an axis parallel to said longitudinal feeding direction L. 
     According to an embodiment, with respect to a cross-section plane perpendicular to the longitudinal feed direction L, the cross-section of the insertion channels  56 , at the spinning chamber  40 , has a triangular profile converging and rounded at said groove bottoms  60 . 
     It is also possible to provide insertion channels  56  of the webs N 1 , N 2  which are substantially straight and parallel to said longitudinal feed direction L. 
     According to a further possible embodiment ( FIG. 10 ), the introducer nozzle  52  comprises flat insertion channels  56  which are angled so that respective planes tangent to the channels identify an angle at the vertex α between 160° and 178°, preferably said angle at the vertex α is equal to 170°. 
     According to a possible embodiment, the drawing device comprises at least one dual channel condenser  64 , comprising a pair of channels  68 ,  72 , wherein each channel  68 ,  72  houses and guides one of said webs N 1 , N 2  in the longitudinal feed direction L, limiting the excursion of the webs in the transverse direction Z-Z, perpendicular to said longitudinal feed direction L. 
     The dual channel condenser  64  is arranged in a centreline M-M between at least one pair of drawing cylinders  24 , each acting on a respective web N 1 , N 2 . 
     Each channel  68 ,  72  is closed or self-threading, and comprises a seat  74  having a first input section  76 , perpendicular to the longitudinal feed direction L to facilitate insertion of the web N 1 , N 2 , and a second retention section  80 , directed in a transverse direction Z, perpendicular to the first input section  76 , so as to limit the transverse distance of the web N 1 , N 2  with respect to the centreline M-M of the condenser  64 . 
     As seen, the drawing device  20  preferably comprises a plurality of pairs of drawing cylinders  24 , arranged in series along the longitudinal feed direction L, each pair being provided with a dual channel condenser  64 . 
     Preferably, in said series of condensers  64 , the second retention portion  80  of each pair of successive cylinders  24  is lower than the corresponding second retention portion  80  of the preceding pair of cylinders, along said longitudinal feed direction. In this way, gradually, or progressively, the webs N 1 , N 2  are approached towards the centreline M-M and therefore towards the centre of the subsequent spinning chamber  40 . 
     It is possible to provide both embodiments in which said split condensers are open and therefore self-threading, and closed, non-self-threading condensers. 
     The operation and therefore the drawing method of an apparatus according to the present invention will now be described. 
     In particular, the apparatus introduces the two webs N 1 , N 2  through the introducer elements  8 , 12  in the drawing devices. 
     Said at least two webs N 1 , N 2  of textile fibres can be equal to each other or can be different from each other in quality, thread count, colour and/or material. 
     The webs N 1 , N 2  are then drawn progressively by the pairs of drawing cylinders  24  until the desired drawing is obtained. 
     The drawn webs N 1 , N 2  always separated from each other are fed into the spinning chamber  40  by the introducer nozzle  52 . Inside the spinning chamber  40 , the webs N 1 , N 2  are subjected to the air jets  44 ,  48  which cause them to twist and mix, in a uniform, symmetrical and homogeneous manner. 
     It is important that the two webs N 1 , N 2  are drawn separately up to insertion and output from the introducer nozzle  52 , to then be joined exclusively inside the spinning chamber  40 . 
     Preferably, the drawing and spinning method comprises the step of progressively approaching the webs N 1 , N 2  during the subsequent drawing steps, by using condensers  64 , without ever joining the webs N 1 , N 2  before the respective entry into the spinning chamber  40 . 
     It is possible to provide the step of modifying the degree of drawing of the two webs N 1 , N 2 , upon transit through said pairs of drawing rollers  24 , so as to feed to the spinning chamber  40  webs N 1 , N 2  different from each other and with a different degree of drawing. 
     As can be appreciated from the description, the present invention allows overcoming the drawbacks of the prior art. 
     In particular, the present invention allows eliminating the problem of bars in the case of obtaining mixed yarns by means of air spinning machines. 
     Said mixed yarns comprise both two webs of different colours, but also webs of the same colour, of the same material and of mixed material (for example cotton/polyester or viscose/polyester). 
     Moreover, the present invention allows the colorimetric yield of the final yarn to be controlled with extreme precision. 
     The principle underlying the present invention, which allows the aforementioned problems to be solved, is basically to make the action on the fibres as uniform as possible. This is achieved, as seen, in two ways. 
     The first way is to make the entry of the fibres symmetrical, that is as much as possible aligned with the centre of the spinning chamber. This causes the distance between the point of injection of the air in the chamber and the insertion point of the fibres to be the same for both fibre flows of the respective webs. 
     In this way, despite the fact that the speed of the air leaving the injection points decreases rapidly as the fluid is expanding rapidly, the two fibre flows are subjected to very similar aerodynamic actions. 
     The second method consists in changing the distance between the main air flow and the fibre area. 
     In particular, by bringing the inlets of the fibres in the chamber as close as possible to the centre, the influence of the air flows and the relative non-uniformity due to any differences in these flows is limited. 
     In general, the feed channels are separated up to the entry into the spinning chamber, where the webs are coupled; furthermore, said webs, coming out of the feeding channels, come out as close as possible to the centre of the spinning chamber so as to guarantee a symmetrical and homogeneous mixing. Thanks to this symmetry and homogeneity, it is possible to exactly replicate and control the mixing of the fibres inside the spinning chamber, both in order to avoid barring, and in order to dose the colours exactly and at will to obtain the desired final effect of coloration. 
     Therefore, on the one hand the webs are prepared with extreme precision but distanced and separated before the entry into the spinning chamber, and on the other hand they twist and mix in the position closest to the centre, inside the spinning chamber. 
     The dual channel, self-threading condensers allow further improvement of the web preparation and threading operation before entering the spinning chamber. 
     Preferably, as seen, a condenser is positioned between each pair of drawing rollers, with the width of separation of the webs gradually decreasing from the entry into the drawing group to the exit from the drawing group and entry into the spinning chamber. 
     In this way, the approach of the webs, which remain strictly separated in the drawing group, takes place gradually, up to the entrance into the spinning chamber. 
     In order to satisfy contingent and specific needs, a man skilled in the art will be able to make numerous modifications and variations to the air-jet spinning methods and devices for mixed yarns described above, all of which fall within the scope of the invention as defined by the following claims.