METHOD TO WIND DOWN A YARN PACKAGE AND DEVICE TO PERFORM THE METHOD

Abstract: Method to wind down a yarn package (11) on spinning machines comprising a spindle (18) to rotate the yarn package (11), means (13-14-15) to wind yarn (10) on the yarn package (11) and drafting rolls (12) to feed the yarn (10), the winding down being achieved by reverse rotation of the yarn package (11) in relation to the direction of rotation of the spinning step. Device for the winding down on yarn packages (11), which employs the above method and in which a spacer ring (22) is fitted in a stationary manner on a spindle (18) and comprises an upper hollow (23), a lower hollow (123), a protruding surface (28) and substantially sharp edges (26).

Description: This invention concerns a method for winding down a yarn package and also a device for performing such method. To be more exact, the invention concerns a method, and also the relative device to perform the method, which are suitable for winding down the yarn to be wound below a yarn package. When the formation of a yarn package on ring spinning machines has ended, there follows the operation of winding down the yarn below the package, or winding the underwinding yarn, on a sleeve of the spindle. With the winding down some coils of yarn are wound on the spindle, the yarn being held at that position. When winding down has taken place, the full yarn package can be doffed and a new tube donned, the yarn thus remaining already arranged for the start-up of the spinning machine once more. On ring spinning machines the winding down operation as for example described in FR-A-2461034 takes place by lowering the ring rail from the upper end of the yarn package to the base of the spindle at the level of a suitable tract of the spindle, where the coils of yarn are wound, this tract being normally called the "underwinding sleeve". During the whole above mentioned winding down step the spinning machine continues spinning, that is to say, the yarn arrives from the drafting unit and is wound in descending coils on the body of the yarn package first of all and then on the underwinding sleeve of the spindle. If the ring rail is to be lowered while the spinning machine is working, the winding element, the ring and traveller for instance, must be coaxial with the yarn package and have a radial dimension greater than the diameter of the package. When the ring rail has been lowered, the yarn package is free to be doffed. After the doffing by hand or with automated devices the yarn is broken in its segment between the yarn package and the winding down coils on the underwinding sleeve. Some descending coils called "winding down coils" remain on the yarn package. The winding down coils on the underwinding sleeve have the same direction of rotation as the coils of yarn wound on the yarn package. During the winding down the yarn package is rotated in the same direction as during spinning. In practice the known winding down operation is the last step in the spinning before the machine is stopped. The yarn required for the winding down is supplied until the last moment by the drafting unit. If the winding element on a spinning machine has a radial dimension smaller than the diameter of the yarn package, it is no longer possible to lower that element along the axis of the package and it becomes necessary to displace the element beforehand from that axis. However, in this situation it is no longer possible to carry on spinning and therefore no yarn will arrive from the drafting unit during the step of lowering the ring rail and winding down. So as to be able to perform a winding down operation of a traditional type even in this situation, it is necessary beforehand to provide spare yarn to perform the winding down . The number of winding down coils which can be laid on the underwinding sleeve will therefore depend on the length of spare yarn provided beforehand. The length of the segment of spare yarn has to be sufficiently long if it is desired to provide a safe winding down operation with a good anchorage of the yarn on the spindle sleeve, that is, a winding down which will ensure the breakage of even the strongest yarns when the package is doffed. To obviate such drawbacks and obtain a plurality of advantages the present applicant has designed, tested and embodied a new method for winding down on the yarn package and has also designed devices suitable to perform such method. According to the invention the new method obviates the necessity of feeding yarn from the drafting unit or providing spare yarn before the winding down during the winding down step. The invention enables the yarn needed for formation of the winding down coils to be taken from the yarn package at the moment when the winding down is performed. According to the invention the direction of rotation of the spindle during the winding down is the opposite of that during spinning. A further advantage of the invention is the fact that the winding down coils on the underwinding sleeve are wound in the opposite direction to that of the coils made during spinning and therefore tend to become unravelled automatically with the increase in the speed of rotation of the spindle when the machine is started up again. By means of the invention it is also possible to wind any desired number of winding down coils on the underwinding sleeve and to apply a constant and very restricted tension to the yarn throughout the whole winding down segment. For this purpose the underwinding sleeve is rendered able to idle on the spindle and to cooperate with a spacer ring solidly fixed to the spindle. Such an embodiment enables many winding down coils to be wound, even with very thin, weak yarns. The new method can therefore be employed for any type of winding device and, for example, advantageously with winding devices having radial dimensions smaller than the diameter of the yarn package. With the winding down method of the invention the loose end of the yarn package when doffed will be shorter since the winding down coils are not formed on the yarn package, and this entails a saving of yarn. Moreover, the breakage of the yarn will be localised at the sharp edge of the spacer ring and therefore it will be easier to find the end of the yarn when winding starts. According to the invention the following steps are entailed. When the yarn package is complete, the spinning machine is stopped and the spindles and drafting unit halt. The yarn goes from the drafting unit to the winding means and is then wound on the yarn package. The yarn package is then rotated in the opposite direction to the spinning direction, and at the same time the segment of yarn about to be wound on the yarn package is diverted and lowered to a determined position at about the lower end of the underwinding sleeve. Such diversion of the yarn is made possible by the unwinding of yarn from the package owing to the rotation in the reverse direction in cooperation with the winding means. In a variant the diversion of the yarn is obtained with the cooperation of the winding means of other means able to take the yarn to the lower end part of the underwinding sleeve. According to the invention the reverse rotation of the yarn package is ended when the winding down is completed. During the reverse rotation of the yarn package the yarn is pulled by the package owing to its hairiness and is arranged on the surface of the package in a reversed arc. As rotation proceeds, the yarn comes into contact with the outer edge of the spacer ring, passes over the ring and reaches the underwinding sleeve, on which it is wound. The invention is therefore embodied with a method to wind down a yarn package on spinning machines comprising a spindle to rotate the yarn package, means to wind yarn on the yarn package and drafting rolls to feed the yarn, the method being characterized in that the winding down is achieved by reverse rotation of the yarn package in relation to the direction of rotation of the spinning step and by displacement of the yarn from a position corresponding with the upper end portion of the yarn package to a position corresponding with the lower end portion of an underwinding sleeve. This invention is also embodied with a device for the winding down on yarn packages, which employs the above method and is characterized in that a spacer ring is fitted in a stationary manner on a spindle and comprises an upper hollow, a lower hollow, a protruding surface and substantially sharp edges and that the spindle comprises drive means which are capable of reverse rotation. The attached figures, which are given as a non-restrictive example, show the following:- Figs.1a, 1b and 1c show the known art; Figs. 2 and 3 show preferred embodiments of the invention. Figs.1a, 1b and 1c show the operation of winding down a yarn 10 at the end of formation of a yarn package 11 on ring spinning machines, for instance. The yarn 10 is fed by feeder rolls 12 of a drafting unit and is guided by a traveller 13 able to slide on a ring rail 15. Descent of the rail 15 causes coils 16 of yarn 10 to be wound first of all on the body of the yarn package 11 and thereafter on an underwinding sleeve 17 as far as the base of a spinning spindle 18. Some coils 16 are wound on the sleeve 17 and held in that position. When the yarn package 11 is doffed, the yarn 10 is broken in its segment between the yarn package 11 and the winding down coils 16 lying on the underwinding sleeve 17. Figs.2a, 2b, 2c, 2d and 2e show the steps of the winding down of the invention. As an example, the method is shown as applied to a ring spinning machine but can be applied also to other spinning systems such as cap spinning frames and the like. Fig.2a shows the step of completion of the yarn package 11, with the ring rail 15 in a position corresponding to the upper end 19 of the package 11. The feed rolls 12 and spindle 18 are halted. Fig.2b shows the step in which the ring rail 15 is raised above the upper end 19 of the yarn package 11 and is displaced sideways in relation to the package 11. In this step the spindle 18 begins to rotate in the opposite direction to the spinning direction. The yarn 10 now comprises a divergent segment 20 owing to the sideways displacement of the ring rail 15 and the reversed rotation of the spindle 18. Fig.2c shows the descent of the ring rail 15 outside the yarn package 11. Fig.2d shows the position of the lower end of the travel of the ring rail 15 in correspondence with the lower end portion 30 of the underwinding sleeve 17. The yarn 10 is set in rotation by the hairiness of the yarn package 11 and becomes arranged on the body of the package in the form of an inverted arc 21. A spacer ring 22 solidly fixed to the spindle 18 comprises an upper hollow 23 to accommodate the yarn package 11, thus reducing the distance between the first spinning coils 16 wound on the yarn package 11 and a protruding surface 28 of the spacer ring 22. The yarn 10 runs momentarily on the protruding surface 28 of the spacer ring 22 and is wound thereafter on the underwinding sleeve 17. Fig.2e shows diagrammatically a variant for the diversion of the yarn 10. A divertive element 29, which may be a pin or a lever or a similar element, cooperates momentarily with the yarn 10 by means of a drive unit positioned on the spinning machine and brings the yarn to a position corresponding with the lower end 30 of the underwinding sleeve 17. Fig.3 gives an enlarged view of the lower end portion of the spindle 18 fitted to the spindle rail 24. The tube 25 of the yarn package, 11 rests its lower end in the upper hollow 23 machined in the upper portion of the spacer ring 22 solidly fixed to the spindle 18. The spacer ring 22 comprises in its lower side a lower hollow 123 with substantially sharp edges so as to facilitate and localise the breakage of the yarn 10 when the yarn package is doffed. The underwinding sleeve 17, which is fitted so as to idle on the spindle 18 and has a substantially truncated-cone shape to assemble the underwinding coils, cooperates with the lower hollow 123 of the spacer ring 22. The underwinding sleeve 17 comprises a lower terminal safety flange 27 to retain the underwinding coils.

Claims: Method to wind down a yarn package (11) on spinning machines comprising a spindle (18) to rotate the yarn package (11), means (13-14-15) to wind yarn (10) on the yarn package (11) and drafting rolls (12) to feed the yarn (10), the method being characterized in that the winding down is achieved by reverse rotation of the yarn package (11) in relation to the direction of rotation of the spinning step and by displacement of the yarn (10) from a position corresponding with the upper end portion (19) of the yarn package (11) to a position corresponding with the lower end portion (30) of an underwinding sleeve (17). Method as claimed in Claim 1, in which the yarn (10) required for the winding down is unwound from the yarn package (11) at the same time as the formation of the winding down coils (16). Method as claimed in any claim hereinbefore, in which the yarn (10) is positioned in a stationary manner in correspondence with the lower end portion (30) of the underwinding sleeve (17). Method as claimed in any claim hereinbefore, in which the yarn (10) runs on a protruding surface (28) of a spacer ring (22) solidly fixed to the spindle (18). Method as claimed in any claim hereinbefore, in which the formation of the underwinding coils (16) takes place on an underwinding sleeve (17) installed so as to be able to rotate on the spindle (18). Method as claimed in any claim hereinbefore, in which the underwinding coils (16) are wound on the underwinding sleeve (17) in a direction opposite to that of the rotation of spinning. Method as claimed in any claim hereinbefore, in which the feed rolls (12) are halted during the winding down step. Device for the winding down on yarn packages (11) which employs the method of the claims hereinbefore and is characterized in that a spacer ring (22) is fitted in a stationary manner on a spindle (18) and comprises an upper hollow (23), a lower hollow (123), a protruding surface (28) and substantially sharp edges (26), and in that the spindle (18) comprises drive means which are capable of reverse rotation. Device as claimed in claim 8, in which an underwinding sleeve (17) having a substantially truncated-cone shape is installed so as to be able to rotate on the spindle (18) and the spacer ring (22) is positioned between the spinning tube (25) and the underwinding sleeve (17). Device as claimed in Claims 8 and 9 in which a divertive element (29) cooperates momentarily with the yarn (10) so as to bring the yarn (10) into correspondence with the lower end portion (30) of the underwinding sleeve (17).

Inventors: GERIN, UMBERTO, LANCEROTTO, FABIO, LANT, DANNY, MARCHIORI, MIRKO
Applicants: MASCHINENFABRIK RIETER AG
Application year: 1988
Main classification: D01H9
IPC codes: D01H1, D01H13, D01H9, D01H7