Abstract:
A method and apparatus for the simultaneous centralized controlled adjustment of the braking force of yarn brakes of a plurality of twist spindles of a two-for-one twisting machine are provided, whereby each twist spindle is of the type having, in its hollow shaft, a yarn brake supported between two brake rings with one of the brake rings being rotatable in response to a downward axial pressure thereon in a manner such that the brake ring undergoes a discrete axial displacement to a new axial position. A support frame to which yarn balloon guides are mounted exerts a downward axial force such that the yarn balloon guides simultaneously exert downward axial pressure on the yarn intake conduits of the twist spindles which, in turn, effects axial displacement of the rotatable and axially adjustable brake ring on the yarn intake conduit of each twist spindle into new axial positions.

Description:
BACKGROUND OF THE INVENTION  
         [0001]    The present invention relates to a method and apparatus for the simultaneous centralized control of capsule-like yarn brakes of several twist spindles of a two-for-one twisting machine.  
           [0002]    DE 44 08 262 C2 discloses an apparatus for the central control of a capsule-like yarn brake of a twisting machine, especially a two-for-one twisting machine. This conventional apparatus includes a control device and a common compressed air unit which is communicated with the twist spindles via connecting units each associated with a respective twist spindle and operable to deliver air pulses to a pressurized air cylinder coupled to a brake ring of the respective twist spindle, the control device controlling the common compressed air unit to deliver pressurized air pulses to the pressurized air cylinders, whereby the pressurized air cylinders, upon receipt of the air pulses, effect an axial displacement of the rotatable brake rings of all of the capsule-like yarn brakes over a predetermined extent.  
           [0003]    DE PS 32 43 157 discloses a twist spindle having a capsule-like yarn brake, which is supported between upper and lower brake rings. The upper brake ring is mounted to a support body at the lower end of a yarn intake conduit of a twist spindle and is resiliently biased by a spring in the direction of the lower, second brake ring. The support body is provided with a plurality of support shoulders distributed around its circumference at different axial positions so that a respective one of the support shoulders is supported on a stationary detent. An adjustment of the braking force of the capsule-like yarn brake is effected in a manner such that the yarn intake conduit is raised against the force of the spring which biases the support body and, thereafter, the yarn intake conduit is rotated through a pre-determined angular range of traverse such that another support shoulder of the support body comes to rest against the detent. This conventional device is thus directed to an individual adjustment and, especially, a manual individual adjustment, of each individual capsule-like yarn brake.  
         SUMMARY OF THE INVENTION  
         [0004]    The present invention offers a solution to the challenge of providing a method and an apparatus for the simultaneous centralized controlled adjustment of the capsule-like yarn brakes of a plurality of twist spindles of a two-for-one twisting machine such that the need for a dedicated pressurized air system can be avoided.  
           [0005]    Summarizing the prevalent characteristics of the present invention, the present invention is particularly characterized in that it exerts, in a purely mechanical operation implemented via a plurality of yarn balloon guides commonly supported on a support frame, a sufficiently high pressure on the yarn intake conduits of a plurality of twist spindles such that the yarn intake conduits, which each support one of the two respective brake rings of the respective twist spindle, are axially displaced against the bias of a spring force to an extent such that a brake ring rotation advances the brake ring to a different axial position relative to the other, second respective brake ring following each release of the yarn intake conduit from the axial pressure thereon.  
           [0006]    An embodiment of the present invention is described in the following description taken in connection with the figures of the drawings. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]    [0007]FIG. 1 is a sectional view of a two-for-one twisting machine having a plurality of yarn balloon guides commonly mounted on a yarn guide frame, which is movable upwardly and downwardly;  
         [0008]    [0008]FIG. 2 is an enlarged sectional view of a twist spindle having a hollow shaft in which a capsule-like yarn brake is disposed;  
         [0009]    [0009]FIGS. 3 a - 3   c  are each an enlarged perspective view of a portion of the adjustment unit at a respective different position thereof during movement of the adjustment unit to adjust the braking force of the twist spindle relative to a stationary detent;  
         [0010]    [0010]FIG. 4 is an enlarged perspective view of a variation of the one embodiment of the adjustment unit; and  
         [0011]    [0011]FIG. 5 is an enlarged perspective view of a twist spindle having a variation of the embodiment of a yarn balloon guide. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0012]    [0012]FIG. 1 shows a sectional view of a two-for-one twisting machine which supports the yarn balloon guides  9  of a plurality of twist spindles S arranged in neighboring relation to one another, the yarn balloon guides  9  being commonly mounted to a common yarn guide frame  11  which is movable—in a not illustrated guide—upwardly and downwardly parallel to the axes of the twist spindles S in the direction of the double arrow F 1 .  
         [0013]    The yarn guide frame  11  is suspended by means of suspension hangers  12  on a shaft  13 , which is rotatably driven by a rotation drive  14  operatively coupled to a motor  15 . The downward movement of the yarn guide frame  11  is effected under the influence of gravity by corresponding controlled actuation of the motor  15 . The possibility thus exists to position the yarn balloon guides  9  at differing heights over the yarn intake conduits  3 , whereby, to exert an influence on the yarn twisting process, the formation of yarn balloons can be controlled. In accordance with the present invention, the yarn balloon guides  9  can be displaced downwardly through corresponding adjustment of the yarn guide frame  11  to such an extent that the yarn balloon guides  9  exert a downward pressure on the yarn intake conduits  3  of a plurality of the twist spindles S, whereby the yarn intake conduits  3  are pressed downwardly. In this manner, as will be hereinafter described, the possibility exists to provide a centrally controlled adjustment of the yarn brakes of a plurality of spindles S arranged in neighboring relationship to one another.  
         [0014]    [0014]FIG. 2 shows a portion of the hollow shaft  2  of a rotationally symmetric housing  16  in which is disposed a capsule-like yarn brake  11  and an adjustment unit  18  which is responsive to downward pressure on the yarn intake conduit  3 , the adjustment unit  18  being operable to effect a variation of the braking force of the capsule-like yarn brake  11 . The adjustment unit  18  is secured to the bottom end of the yarn intake conduit  3  and comprises a cylindrical housing  27  open towards its bottom for receipt therein of a helical spring  28  which biases the adjustment unit  18  upwardly.  
         [0015]    The housing  16  is closed on its topside by a threaded cover  19  through which the yarn intake conduit  3  is guided outwardly of the housing  16 . The capsule-like yarn brake  11  includes a bullet-like brake which, in conventional manner, is comprised of two displaceable tube portions  11 . 1  and  11 . 2  biased by a spring to move axially away from one another and each of which includes a cup or cap-shaped end portion. The lower tube portion  11 . 2  is supported against a brake ring  20 , which is disposed in a brake ring carrier  21  disposed in an axial guide or groove  21 . 1 . The brake ring carrier  21 , which is supported against a helical spring  22 , is sealingly guided in a housing bore  16 . 2  formed in the housing  16  such that, for purposes of effecting a pneumatic yarn threading or intake of yarn, an under-pressure is created below the yarn ring carrier  21  so as to effect downward movement of the yarn ring carrier. The lowered yarn ring  20  thus releases the bullet-like yarn brake  11  to fall whereupon it is then caught by a support ring  16 . 3  stationarily mounted in the housing; the support ring  16 . 3  has a partial opening  16 . 31  such that a yarn introduced through the yarn intake conduit  3  can be suctioned in through the yarn intake  8  into the bore  21 . 1  and guided past the released bullet-like brake  11 . A yarn threading system of this type is described in DE 44 08 262 C2 and is, in any event, the basic configuration of the yarn intake assembly as described in the hereinafter-described adjustment unit  18 .  
         [0016]    A first annular upper toothed rim  40  is disposed on the adjustment unit  18  above the housing  27  and a second annular lower tooth rim  41  is disposed above the housing  27  as well. The upwardly directed teeth of the lower toothed rim  41  form therebetween axial spaces in the form of openings/slots whose bases or bottoms form notches or, respectively, support shoulders which are distributed about the circumference of the toothed rim at differing axial heights therearound and each notch or support shoulder is engaged upon its turn by a radially inwardly projecting detent  29  as a function of the rotational position of the adjustment unit  18 .  
         [0017]    The downwardly directed teeth of the upper-toothed rim  40  form therebetween axially extending slots opening downwardly or, respectively, form downwardly opening notches.  
         [0018]    Reference is now had to FIGS. 3 a - 3   c  for a description of the configuration of the teeth of the two toothed rims  40  and  41 ; the arrow F 2  indicates the rotational direction of the adjustment unit  18 .  
         [0019]    The flanks  40 . 1  and  41 . 1  of the teeth of the upper and lower toothed rims  40  and  41  which extend in the rotational direction F 2  have substantially axial extents. The down sloping flanks  40 . 2  or, respectively,  41 . 2  of the upper and lower toothed rims  40  and  41  are configured as respective rising or falling angled surfaces which form an angle of approximately 45° relative to the rotational direction. The tips or peaks of the teeth of the upper-toothed rim  40  are offset from the tips or peaks of the teeth of the lower toothed rim  41  in the rotational direction by an amount which is slightly greater than the diameter of the detent  29 .  
         [0020]    [0020]FIG. 3 a  shows an operational condition in which the lower toothed rim  41  is engaged by the detent  29  such that the detent is seated in a notch I between two neighboring teeth of the lower toothed rim with the portion of the adjustment unit  18  comprised of the lower toothed rim  41  being upwardly biased by the spring  28 . If the adjustment unit  18  is displaced downwardly in the direction of the arrow F 3  via a downward pressure on the yarn intake conduit  3 , the detent initially assumes the position shown by the broken lines  29 ′ seen in FIG. 3 b.  Upon further downward pressure on the yarn intake conduit  3 , the detent traverses along the toothed flank  40 . 2  extending away from the rotational direction f 2  to thereafter achieve the intermediate position  29 ″ shown in FIG. 3 c  in correspondence with the partial rotation of the adjustment unit  18  in the direction of the rotation direction F 2 . The movement of the detent  29  relative to the adjustment unit  18  follows thus along the path of the bent arrow F 5  shown in FIG. 3 a.  It is to be understood that the stationary detent  29  does not axially change its position but, rather, the adjustment unit  18  undergoes a partial rotation during this process.  
         [0021]    If, thereafter, the yarn intake conduit  3  is again released, the adjustment unit  18  is again biased upwardly, as seen in FIG. 3 c,  in the direction of the arrow F 4  due to the biasing action of the spring  28  so that the detent  29 —following the path shown by the bent arrow F 6 —seats into the next following notch  11 , whereby there follows a sliding movement of the detent  29  along the flank  41 . 2  in the direction of the rotation direction F 2  upon a further partial rotation of the adjustment unit  18 .  
         [0022]    By virtue of the lowering and subsequent release of the yarn intake conduit  3  and, thus, of the adjustment unit  18 , there follows a sectional rotation of the adjustment unit  18  in the rotational direction F 2 . Since each notch is lower than the immediately preceding notch, it follows, as the detent  29  seats into the respective next following notch, that the brake ring  23  is disposed in progressively lower positions following each operation to lower and release the yarn conduit  3 , thus leading to an increase in the braking force.  
         [0023]    The braking force can thus be adjusted in a step-wise manner through individual downward pressure and release sequences of the yarn intake conduit  3  until the braking force has been increased to a maximum value, which value is predetermined by the depth of the deepest notch in the lower toothed rim  41 .  
         [0024]    Through multiple sequential actuation—that is, multiple actuation involving downward pressure and release of the yarn intake conduit  3 —the yarn braking force can be increased until the detent  29  is eventually seated in the deepest notch of the lower toothed rim  41 .  
         [0025]    By sequential or subsequent activation of the yarn intake conduit  3 , the detent  29  is moved into the next following—that is—the highest disposed notch—of the lower toothed rim  41 , which corresponds to the braking force adjustment position of the lowest value.  
         [0026]    The toothed rims  40 ′,  41 ′, as seen in FIG. 4, can be configured as lower components freely rotatable relative to the remainder of the adjustment unit  18  but not, however, adjustable relative thereto in the axial direction, with the toothed rims  40 ′,  41 ′ being supported by, from below, a collar of the housing  27  and, from above, a detent body  60  which is securely mounted via, for example, a threaded screw  61 , on the yarn intake conduit  3 .  
         [0027]    The yarn balloon guides can alternatively be configured to be self-centering with respect to the associated yarn intake conduits  3 —e.g., as truncated ball-shaped yarn balloon guides  9 ′, as seen in FIG. 5.  
         [0028]    The specification incorporates by reference the disclosure of German priority document DE 100 45 909.9.  
         [0029]    The present invention is, of course, in no way restricted to the specific disclosure of the specification and drawings, but also encompasses any modifications within the scope of the appended claims.