Patent Publication Number: US-11377761-B2

Title: Spinning apparatus, air spinning apparatus in particular, with continuous adjustment of a yarn accumulation system and related method of continuous adjustment of a yarn accumulation system in a spinning apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority to Italian Patent Application No. 102019000001195, filed Jan. 28, 2019, the entire contents of which are hereby incorporated by reference herein. 
     FIELD OF APPLICATION 
     The present invention relates to a spinning apparatus, an air spinning apparatus in particular, with continuous adjustment of a yarn accumulation system and related method of continuous adjustment of a yarn accumulation system in a spinning apparatus. 
     BACKGROUND 
     As known, in spinning systems with no accumulation, the possibility of making conical reels (3° 30′, 4° 20′, 5° 57′) is not ensured because there is no possibility of balancing the difference in speed between tail and head of the reel, nor may it be joined with traditional-type systems (for example of the splicer-type) because there is no possibility of “stopping” the spinning for the joining cycle: therefore, there is an obligation to use more complicated reattachment systems which have the great defect of making joins of lesser quality. 
     Known accumulation spinning systems instead also allow conical reels to be made, but at the same time have the problem of stressing the yarn with continuous attaching/detaching cycles of the reel to/from the related pulling cylinder. The system is intrinsically adapted to eliminate the repps because the continuous attachment/detachment randomly varies the speed of the reel (for example, systems of this type which are activated at the critical diameter ratios, are used in winding). The frequency of the attachment/detachment cycles however cannot be accurately set nor can it be adjusted in a uniform manner on all the heads of the spinning apparatus because the tension adjustment function is typically handled by a highly sensitive magnetic-type friction system which requires a fine adjustment to work well. 
     The known spinning systems which use this type of attachment/detachment cycle moreover do not allow well-made reels to be made because the warp tension suddenly changes in the presence of the cycle, causing layers with different tension to be deposited and thus increasing the possibility of having dropped coils at the edges and therefore the lack of homogeneity of the corresponding reel. 
     SUMMARY 
     The need is therefore felt to solve the drawbacks and limitations mentioned in reference to the prior art. 
     Such a need is satisfied by a spinning apparatus with continuous adjustment of a yarn accumulation system disclosed herein, and by a related method of continuous adjustment of a yarn accumulation system in a spinning apparatus disclosed herein. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Further features and advantages of the present invention will become more comprehensible from the following description of preferred and non-limiting embodiments thereof, in which: 
         FIG. 1  shows a perspective view, with partially separate parts, of a spinning apparatus with continuous adjustment of a yarn accumulation system, according to one embodiment of the present invention; 
         FIGS. 2 to 3  show front views, in assembled configuration, of a spinning apparatus with continuous adjustment of a yarn accumulation system in  FIG. 1 ; 
         FIGS. 4 to 10  show graphs of the trend of the yarn accumulation and of the collection or rotation speed of the reel according to possible adjustment methods according to the present invention. 
     
    
    
     The elements or parts of elements common to the embodiments described below will be indicated using the same numerals. 
     DETAILED DESCRIPTION 
     With reference to the aforesaid drawings, a spinning apparatus with continuous adjustment of a yarn accumulation system, which is better described later, is indicated as a whole with  4 . 
     It is worth noting that the present invention preferably, but not exclusively, applies to a spinning apparatus of the air type, i.e. an air-jet spinning apparatus. Such an invention may also be applied to a spinning apparatus having a mechanical spinning rotor, for example. 
     In any case, for the purposes of the present invention, the spinning apparatus  4  may be of any type, shape and size. 
     Said spinning apparatus  4  comprises a spinning device  8  comprising a spinning chamber  12  for yarn production. For example, the spinning chamber  12  may comprise a plurality of air jets (not shown) oriented in direction which substantially is tangential to corresponding ribbons arranged in input in the spinning chamber  12  itself so as to weave said ribbons with one another and obtain a single yarn F in output from the air spinning chamber  12 . 
     The spinning apparatus  4  further comprises a reel  16  on which said yarn produced by the spinning device  8  is wound. 
     Reel  16  is rotatably influenced by a yarn guide  20  shaped to impart a rotation movement of reel  16  for winding the yarn and a traversing movement of the yarn winding on reel  16  itself. Reel  16  rotates about a substantially horizontal rotation axis X-X. Reel  16  may have both cylindrical shape and conical shape with respect to said rotation axis X-X. 
     The rotation of reel  16  may typically occur by means of a winding cylinder  24  (also called pulling cylinder) in direct contact with an outer side surface  28  of reel  16  so as to pull the latter in rotation by friction, in known manner. Different devices suitable to allow the rotation of reel  16  about its rotation axis X-X may also be employed to obtain the winding of the yarn. 
     The spinning apparatus  4  further comprises an accumulation device  32  of the yarn produced, arranged between the spinning device  8  and reel  16 , shaped to create a reservoir of yarn not wound on reel  16 . 
     In other words, the accumulation device  32  constitutes a kind of reservoir of yarn which is wound thereon before being wound on the reel. During the reattachment step of the yarn, the yarn which continues being produced by the spinning device  8  is wound about the accumulation device  32 , which typically is shaped as a cylindrical body, preferably a concave cylindrical body. 
     As mentioned above, the spinning apparatus  4  further comprises a joining device  36  comprising joining means suitable to join together a first yarn end associated with the spinning device  8  and a second yarn end associated with reel  16 . In other words, the first yarn end is connected to a section of yarn coming out of the spinning device  8  or arranged on the side of the spinning device  8 , while the second yarn end is connected to a section of yarn connected to reel  16  or arranged on the side of reel  16 . 
     Advantageously, the spinning apparatus  4  further comprises a processing and control unit  48  programmed to control the yarn guide  20  according to the spinning pattern so as to adjust accordingly the amount of yarn accumulated in the accumulation device  32 . 
     The spinning apparatus typically comprises a plurality of spinning heads  52 —each spinning head  52  being provided with its own yarn guide  20  which influences a corresponding reel  16 —of its own accumulation device  32  of the yarn produced. 
     The apparatus further comprises at least one yarn presence sensor  56  which detects the presence or absence of yarn wound on the accumulator or accumulation device  32 : thereby the presence of yarn detects the proper operation of the apparatus, while the absence of yarn detects the need to restore the accumulation of yarn on the apparatus without ever reaching the condition of lack of accumulated yarn. 
     According to a further embodiment, there are provided at least two yarn detection sensors  56  arranged at suitable distance from each other: the processing and control unit may be controlled so as to vary the rotation speed of reel  16  so as to always keep the amount of yarn within the limits of said two sensors  56 : thereby the amount of yarn accumulated is made as constant as possible. 
     The yarn presence sensor  56  may be of various types comprising both capacitive-type sensors and resistive-type sensors. 
     Said processing and control unit  48  is programmed to manage each spinning head  52  and the respective devices independently from each other. 
     According to a possible embodiment, the processing and control unit  48  in particular is programmed to continuously adjust the rotation speed of reel  16  so as to make substantially constant the amount of yarn accumulated in the accumulation device  32 . 
     According to an embodiment, the processing and control unit  48  is programmed so that when the spinning cycle begins, it begins to spin with a yarn extraction speed, in output from the spinning device  8 , varying between a minimum and a maximum value. For example, when the spinning cycle begins, it starts to spin with a yarn extraction speed varying between the minimum value of 200 [m/min] and the maximum value of 500 [m/min]. 
     Said yarn is fed to the joining device  36  where it is joined to the yarn coming from reel  16 ; the yarn coming out of the spinning chamber  12 , during the time of the reattachment cycle, is deposited in the accumulation device  32 . 
     Moreover, the processing and control unit  48  is programmed so that, at the end of the yarn joining by the joining device  36 , the yarn collection in reel resumes and the accumulation of yarn in the accumulation device  32  is adjusted by adjusting the rotation speed of the pulling cylinder (or winding cylinder)  24  or collection speed of reel  16 . 
     According to a possible embodiment, the adjustment of the rotation speed of reel  16  occurs so as to:
         keep the amount of yarn accumulated around a threshold value so as not to throw away too much in case of breaking or cutting by default, and to always have a sufficient reserve to compensate for the speed variations between tail and head of the reel,   make the winding tension as regular as possible, preventing it from falling or increasing beyond a certain percentage value (which can be selected as desired), as a function of the emptying or filling step of the accumulation device  32  itself.       

     For example, the processing and control unit  48  is programmed so that:
         after the initial emptying of the accumulation device  32 , following a yarn reattachment step, the processing and control unit  48  determines the optimal value of the reel extraction speed  16 , according to the following step (first self-adjustment step):
 
a) the rotation speed of reel  16  is reduced by a value proportional to the first emptying time of the accumulation device  32 .
       

     First emptying time means the time used the first time to empty the accumulation device  32  of the yarn accumulated. 
     The processing and control unit  48  preferably is programmed so that: 
     b) at regular intervals, the rotation speed of reel  16  is reduced to further promote yarn accumulation in the accumulation device  32 . 
     Thereby, the amount of yarn accumulated in the accumulation device  32  can be increased, when needed. 
     According to an embodiment, the processing and control unit  48  is programmed so that: 
     c) when the yarn presence sensor  56  detects the presence of the yarn, the contingent rotation speed (V 1 ) of the reel is stored in the presence of the yarn. 
     Thus, the processing and control unit  48  is programmed so that: 
     d) at regular intervals, the collection speed of the reel  16  is increased to facilitate the unwinding of the yarn by the accumulation device  32 . 
     According to an embodiment, the processing and control unit  48  is programmed so that: 
     e) when the yarn presence sensor  56  no longer detects the presence of yarn, the processing and control unit  48  stores the contingent rotation speed (V 0 ) of the reel in the absence of yarn. 
     Thus, the processing and control unit  48  is programmed so that: 
     f) said processing and control unit  48  calculates the average speed (Vm)=(V 1 +V 0 )/2 between the reel  16  pulling speed V 1  when sensor  56  detects the presence of the yarn and the reel  16  pulling speed V 0  when sensor  56  detects the absence of the yarn. 
     The resulting average speed value is provided for example, to a proportional-integral regulator (P.I.) conveniently configured to control the rotation of reel  16  at said average speed (Vm). The use of a proportional-integral regulator (P.I.) is only explicative and indicative of one of the methods for controlling reel  16  to rotate at said average speed Vm. 
     The processing and control unit  48  preferably is programmed so that: 
     g) at each change of status of the yarn presence sensor  56 , the relative rotation speed value (V 1  or V 0 ) of the reel is updated, respectively in the presence and absence of yarn. 
     The variations in the time domain of yarn collection speed by reel  16  and of yarn accumulation on said accumulation device  32  following the continuous adjustments made by the processing and control unit  48  are depicted in  FIGS. 4 to 9 , as described later. 
     According to an embodiment, the processing and control unit  48  is programmed so as to:
         vary, where necessary, the tension of the yarn accumulating in the accumulation device  32 , modifying the linear speed of accumulation by a positive and settable % allowing the accumulation of the coils of yarn on the accumulation device  32  to be compacted and regularising the unwinding thereof in output;   compensate for such a variation by the yarn guide  20  which will change its course to maintain the best conditions for the formation of reel  16 .       

     According to a possible embodiment, the processing and control unit  48  is programmed so as to perform the following steps:
         at the instant t=t 0  the yarn joining operation is terminated and the accumulation device  32  must be emptied;   a yarn presence sensor  56  is active;   the rotation or collection speed of reel  16  is increased to rapidly empty the accumulation device  32 ;   at the instant t=t 1  the accumulation device  32  has been emptied beyond a target level (reserve);   the yarn presence sensor  56  is no longer active;   the contingent collection or rotation speed VMAX=V 1  is stored, and then the collection speed itself of reel  16  is reduced in order to increase said target level of yarn accumulation.       

     Moreover, if at the instant t=t 2  the accumulation device  32  is exceeding the target level (reserve),
         the yarn presence sensor  56  is active,   the contingent collection speed VMIN=V 2  of reel  16  is stored and the collection speed is adjusted to an average VAV value between VMIN and VMAX.       

     According to a possible embodiment, the processing and control unit  48  is programmed so as to perform the following steps:
         at each transition of the yarn presence sensor  56  the VMIN or VMAX value is updated, and the corresponding average value VAV is calculated,   with the use of a proportional-integral regulator, the VAV error at full speed is minimized.       

     According to a possible embodiment as mentioned above, the spinning apparatus  4  comprises two yarn presence sensors  56 . 
     The system in particular uses 2 yarn presence sensors  56  assembled on the accumulation device  32  to provide the information for the control upon exceeding a maximum or a minimum accumulation level. In other words, a first yarn presence sensor  56  detects the achievement of a predetermined maximum yarn accumulation level and a second yarn presence sensor  56  detects the achievement of a predetermined minimum yarn accumulation level. 
     The operation over time of the dual sensor solution is shown in  FIG. 10 . 
     After the initial emptying (following the yarn reattachment), the system is to determine the optimal value of the extraction speed of the winding cylinder  24  of reel  16 . 
     Then a first self-adjustment step is performed: 
     at the instant t 0  the joining of the yarn ends is terminated, the yarn produced up to that moment (i.e. during the joining) has been accumulated in the accumulation device  32 , both sensors  56  “see” material. Then the emptying of the accumulation device  32  is started by activating the winding or collection cylinder  24  with a speed greater than the nominal speed. 
     In instant t 1 , the maximum accumulation level sensor no longer sees material: this implies that the yarn accumulation has been reduced with respect to the maximum value. The processing and control unit saves this collection speed value as VMAX. The speed of the collection or winding cylinder  24  can also be further increased to also empty the minimum accumulation level sensor. 
     In instant t 2 , the accumulation device  32  has been emptied to reach the minimum level sensor: this latter sensor detects such a condition and then slows down the extraction to have yarn accumulated again by the accumulation device  32 . 
     In instant t 3 , the maximum accumulation level sensor is active, the accumulation device  32  has accumulated sufficient yarn, thus saves the current or contingent speed as VMIN, and the processing and control unit  48  calculates the average with the VMAX stored earlier to obtain VAV=(VMAX+VMIN)/2. Such an average speed value (VAV) is then applied to the rotation of the collection or winding cylinder  24 . 
     If the VAV value set for the collection or winding cylinder should lead to activation of one of the two (maximum or minimum) yarn presence sensors  56 , the step is implemented of increasing/decreasing VAV by a value inversely proportional to an inactivity time of the sensors  56  themselves. 
     Such a control allows an accumulation varying within the limits set by the mechanical positioning of the yarn presence sensors  56  to be kept, thus allowing the yarn not to be stressed, and a warping tension to be obtained which is as constant as possible. 
     As may be appreciated by what is described, the present invention allows the drawbacks introduced in the known art to be overcome. 
     In particular, the present invention allows the limits to be overcome of the known spinning systems which use attachment/detachment cycles, which do not allow well-made reels to be made because the warp tension suddenly changes in the presence of the cycle, causing layers with different tension to be deposited and thus increasing the possibility of having dropped coils at the edges and therefore the lack of reel homogeneity. 
     Instead, in addition to using the traditional accumulation system, the present invention provides using a yarn guide per individual head which adapts its operating method according to the spinning pattern, thus maintaining all the advantages of the traditional systems, eliminating the reel formation and stress defects on the yarn. 
     A further advantage with respect to the traditional solutions is the one of varying, where necessary, the tension of the yarn accumulating, modifying the linear speed of accumulation by a small positive and settable % allowing the system to compact the accumulation of the coils and regularising the unwinding in output. Such a variation is then compensated for by the yarn guide device which will change its course to maintain the best conditions for the formation of the reel. 
     A further advantage is given by the possibility of uniformly adjusting all the spinning heads, obtaining reels having constant shape, density and content along the whole machine. 
     A person skilled in the art, with the object of meeting contingent and specific needs, can make several changes and variants to the apparatuses and to the spinning methods described above, moreover all contained within the scope of the invention, which is defined by the following claims.