A method for continuous spinning of staple fibres and an apparatus for carrying out said method

Abstract: The method includes a step of drawing the sliver to the form of a drawn roving having the yarn fineness and strengthened by a twist, a step of centrally guiding the yarn being produced by a guide means before its entry on the rotating working surface for guiding the yarn by the effect of centrifugal forces to a traveller arranged at its edge and carried by the working surface, by which the yarn is guided during its transport out of contact with the working surface for being wound on the rotating spool, the axial position of which with respect to the edge of the working surface is changing during the winding-up, wherein the yarn circles during the guiding along the working surface of a single rotating carrier the rotating spool with the wound-up yarn with a higher frequency. The apparatus comprises a drawing device (1), an guiding eyelet (2) arranged centrally on the axis of the spindle, a rotating carrier of the working surface (5) surrounding the spindle (19) and carrying at the edge of the surface a traveller (12), a device for setting the mutual axial position of the edge of the working surface and of the tube (22) mounted on the rotating spindle, wherein the rotational movement of carrier (6) of the working surface (5), is coupled with the rotational movement of the spindle so as to have a higher angular speed of rotation.

Description: The present invention relates to a method of production a yarn by the way of continuous spinning from a sliver and to an apparatus for carrying out the method according to the preamble of the independent claims 1 and 3, respectively. The ring spinning is known as the highest state of technology of the principle of continuous spinning of staple fibres. A shortcoming of this system is, however, the physical limit of revolutions of the spindle, beyond which the method cannot be carried out. This limit is in the range of 25 000 revolutions per minute. This results from the fact that with the increasing speed of the spindles there increases also the real risk that the yarn breaks by the effect of cetrifugal forces. The traveller is also subject to the effects of a centrifugal force and for this reason the increase of spindle revolutions causes further unwanted effects. For example at high speeds the traveller is torn away from the ring and the process of spinning is consequently interrupted. As the cetrifugal force acting on the traveller increases, this results in a quick wear of the traveller and also of the ring in the contact areas. The practice of increasing the productivity of the ring spinning system has concentrated on the following essential problems: It limits the yarn baloon. By a rational construction of the shape of the traveller it tries to limit its tearing away from the ring, and at the same time, to limit its wear, even if this problem is solved particularly by the production technology and by the material composition. In spite of this, the limit of 25 000 revolutions of the spindle per minute is an absolute top value, which is exceptional and on the long run practically not attainable. The structure of the ring yarn, however, is so significant in its utility value that, so far, it was not liable to be fully substituted by the more productive technologies, i.e. the rotor ones. For this reason, various solutions are proposed which try to solve and overcome the cited technical and technological limitations of the speed of yarn building. For example according to DE 31 40 422 A1, which forms the preamble of claims 1 and 3, a ring, pivotally mounted with respect to the machine frame, is driven. At the sane time a ring-shaped baloon limiter provided on two supporting ribs is connected to the rotating ring. The rotational movement of the ring takes place in a range in which the angular speed of the ring is lower than the angular speed of the spindle. This solution provides with respect to the classic ring spinning machine an advantage, residing in the fact that it allows a reduction of the relative speed of the traveller and of the ring, whereby an increase of service life of the ring and of the traveller is obtained. The effect of the moving limiter is more favourable for the surface structure of the yarn. However, as mentioned, the disadvantage of this solution resides in the fact that it allows the raising of the limit of attainable productivity of the ring spinning only to a restricted extent due to the fact that the yarn is unable to resist the load to which it is subjected, particularly in the section downstream of the baloon limiter in the partial balooning. Another technical drawback is constituted by the ribs carrying the limiter, which cause by their ventilation during the rotation oscillations of the partial yarn baloon, which leads to lacks of stability in the spinning process. Precisely that shortcoming does not appear with the solution proposed in DE-PS 1 053 365, where the yarn limiter is constituted by a surface of a bell cavity. The apparatus is arranged in such a way that on a stationary axis mounted in the cover of an electromotor the cited bell is rotatably mounted in bearings and that at the bottom of the bell the yarn guide is mounted. The yarn guide is constituted by a channel inclined with respect to the rotation axis of the bell. On the edge of the bell a ring provided with a traveller is attached. The yarn introduced into the bell, is applied by a centrifugal force to the surface of the bell cavity and is further guided by the traveller before being wound on the spool mounted on the rotating spindle. The bell exhibits lower revolutions than the spool, while the friction between the traveller and the ring builds up an axial tension of the yarn for winding. This apparatus is capable of putting the yarn to a rest and of perfectly limiting the yarn baloon but exhibits one unavoidable technical drawback. In order to allow the forming of the yarn winding, the yarn with the traveller must necessarilly circle the spindle at a frequency corresponding to the frequency of the yarn, reduced by the number of windings of the yarn. Since, however, the yarn guide constituted by the inclined channel does not allow the relative circling of the traveller around the ring at a larger central angle than about one half of the circumference of the ring, it is necessary to let the whole bell circle in a corresponding fashion, depending on the number of windings, the ring with the traveller being the parts of said bell. Even if it is intended with the apparatus described in DE-PS 1 053 365 to solve this problem such that the advantageous difference of revolutions of the spindle and of the bell is achieved by electromotors with position switching, while the electromotor of the bell exhibits a greater slip than the electromotor of the spindle, the problem of achieving an instantaneous state of the difference is a much more complicated one, where the means of a solution thereto either are hitherto unknown or are too complicated and technically little reliable. No doubt, the proposed solution certainly could not work without a perfect indication system, the sensors of which should be able to indicate according to the instantaneous state of the wound yarn package, i.e. of the diameter of the yarn wound-up on the spindle, the necessary difference of frequencies within the limits of an accuracy, which could be subsequently compensated by a relative motion of the traveller in the given range of movement. The most significant shortcoming with this system is of technical nature. The technical means available in prior art are not in a position to safeguard with a sufficient accuracy and in economical way the controlled rotation of the bell at level of revolutions higher than the existing top level of the ring spinning. The fixing of the yarn is achieved only by the final twist, and in the case of a substantial increase of the speed of rotation of the spindle it does not endure the axial loading forces so that the process is unstable, if not impossible. The task of the invention is to propose a method of production of a yarn having a ring character, which would allow to produce the yarn essentially more quickly than it is possible to achieve with the existing method of ring spinning, mastered on a top level, and further to propose a simple apparatus for carrying out said method. The object of the invention is to introduce such a state in the spinning process in which, in the yarn being built, the formed yarn would have, in the part of the process after the drawing step of the yarn supply to the form of a drawn roving having a yarn fineness and prior to the winding of the finished yarn on a spool, a greater number of twists than is the number of twists in the finished yarn on the wound-up spool. To this end the invention proposes a method of production of yarn comprising the features of claim 1. It is advantageous that the yarn is controlled for the guiding on the working surface, for a movement with it and along it mechanically at least on the edge of the working surface by a guiding bottom provided on a circular path along the circumference of the working surface for an independant movement by the effect of the carrying forces of the rotating carrier of the working surface and of the drawing forces in the yarn being wound-up. The invention proposes also an apparatus comprising the features of claim 3. A substantial features of the claimed apparatus resides in the fact that between the drive of the carrier of the working surface and the drive of the spindle there is provided a mechanical coupling. It is also substantial that between the individual electro-drive of the carrier of the working surface and the individual electrodrive of the spindle there is provided an electronic coupling. A preferred feature resides in the fact that upstream of the working surface there is provided a coaxial guiding eyelet, arranged on the same carrier. It is also advantageous that the working surface extends from the part facing the guiding eyelet away from the axis until it passes to acylindrical shape surrounding the spool with the yarn. The invention is explained in more details on examples of an apparatus for carrying out the claimed method and by a description of operation of such an apparatus, with reference to the attached drawings in which : Fig. 1 illustrates one spinning unit arranged on a machine, while in dotted lines there is shown a variant of storage contain of another fiber supply; Fig. 2 shows a detail of the part of the machine including the drawing device and twisting device for two adjacent spinning units; Fig. 3 schematically shows a detail of a spinning unit comprising a part of the drawing device, a guiding eyelet, a strengthening and guiding device and a winding device; Fig. 4 schematically shows a detail of an alternative embodiment of a spinning unit including a part of a drawing device, a guiding eyelet, a strenghthening and guiding device and a winding device; and Fig. 5 shows a detail of an alternative embodiment of the guiding member arranged at the edge of the working surface for an independant movement along the circumference of the working surface. The exemplary embodiment for carrying out the method comprises a drawing device 1 , a guiding eyelet 2 , a strengthening and guiding device 3 and a winding device 4 (Fig.1,2 and 4). The drawing device 1 is known in various embodiments from ring spinning, jet spinning and from other spinning systems and it is consequently not necessary to describe it here to more details. It is to be noted that it is possible to use here a drawing device to which a roving or a fiber sliver is supplied in such a way that on the outlet of the drawing device a drawn roving is available the mass of the length unit of which corresponds to the mass of the length unit of the yarn to be built by the apparatus. The guiding eyelet 2 is arranged concentrically about the extended axis of rotation of the strengthening and guiding device 3 and is arranged either pivotally about said axis (Fig.1,2 and 3) or stationary on the machine frame (Fig.4). The strengthening and guiding device 3 is constituted by a working surface 5 arranged inside the cavity of a rotating carrier 6 and by a guiding member 7 equally arranged on the rotating carrier 6 at the edge 8 of the working surface 5 more remote from the drawing device 1 for an independent movement along the circumference of the working surface. The working surface 5 suitably exhibits a bottle-like shape which extends from the edge 9 adjacent to the drawing device 1 , i.e., from the neck, away from the axis of rotation with its increasing length in a cone-like fashion, until it passes from said conical part 10 to a cylindrical part 11 of the working surface (Fig.2 and 3). The working surface 5 can exhibit only the cylindrical part 11 (Fig.4). An advantageous variant is the embodiment in which the guiding eyelet 2 is arranged on the same rotating carrier 6 in front of the edge 9 of the guiding surface 5 (Fig.3). The guiding member 7 may be provided as a traveller 12 mounted on an orbital path 13 attached to the rotating carrier 6 (Fig.3) or on an orbital path 13 which forms directly part of the rotating carrier 6 (Fig.4). The guiding member can be however constituted also by an eyelet 14 provided on a member 15 pivotally mounted on a rotating carrier 6 in a bearing 16 (Fig.5). There are certainly other solutions possible but they must enable the guiding member, moving together with the rotating carrier, to also perform an independant movement, i.e., for example that the traveller 12 or the eyelet 14 move individually with respect to the rotating carrier 6 , i.e., to move with respect thereto by more than one orbital rotation in the direction of movement of the carrier 6, or by more than one orbital rotation against the direction of movement of the carrier 6 , wherein, however, the relation of absolute movement is valid, according to which the absolute number of revolutions of the traveller 12 is less or at the most equal to the number of revolutions n pp of the carrier 6 . The rotating carrier 6 is constituted by a hollow drum the inner cavity of which has a shape of the previously described working surface 5 . The drum is made from a light alloy and is thin-walled, and, if necessary, is made from a suitable composite, wherein in all the embodiments it is advantageous that the working surface 5 is made from a deposited layer of a suitable material with respect to a preferably low friction with the yarn and a great wear resistance. It is not out of question that in order to improve the friction properties with regard to the yarn by reduction of friction forces the working surface is provided, with a special groove or with a projection for constituting suitable ventilation effects preventing a direct contact of the yarn with the working surface. The rotating carrier is pivotally mounted on rolling or aerostatic bearings 17 and is driven, e.g., by a belt 18 . It is also advantageous that the drum constitutes directly the rotor of an electromotor or is driven by a driven friction roller. Said means, however, are known, and it is therefore not necessary to describe them further in detail. The winding device 4 is constituted by a rotating spindle 19 arranged on a bench 20 with a programm-controlled movement in the direction of the double arrow 21 for setting the mutual axial position of the edge of the working surface and of the spindle 19 . On the spindle 19 a tube 22 for the yarn spool 23 is mounted. According to the selection of the type of the yarn winding on the spool the programm of the movement of the bench in the direction of the arrow 21 is selected. It is also essentially possible that the spindle is rigidly mounted on the machine frame and just the rotating carrier of the working surface 5 is mounted on the bench with the described movement. The goal is a relative movement obtained by current means used in the art of ring spinning so that they need not be described here more in detail. It is advantageous that the spindle is driven by an individual electromotor 24 (Fig.1,4) but it may be also driven by a belt. All the described devices of the spinning device constitute in the complex a spinning unit mounted on a frame 25 of a spinning machine adjacently in rows or eventually suitably arranged on both sides of the machine (Fig.1,2). The moving directions of the rotating carrier 6 and of the spindle 19 are identical. While the rotating carrier 6 rotates with a number of revolutions n pp , the spindle 19 only rotates with a number of revolutions n v <n pp . It is consequently important that the movement of the rotating carrier 6 of the working surface 5 is coupled with respect to the higher angular speed of the carrier 6 either by a mechanical, or by electromechanical or even by an electronic coupling, dependant on which drive of the rotating carrier 6 and of the spindle 19 has been used. The described spinning apparatus works as follows. The fiber roving 27 from the roving spool 28 or a fiber sliver 29 from a sliver can 30 is supplied to a drawing device 1 . From the drawing device 1 a drawn roving 31 is obtained having a mass of the length unit equal to the mass of length unit of the yarn. Immediately downstream of the clamping grip of the last pair of rollers 26 of the drawing device 1 the drawn roving is strengthened by the effect of twists, which enter into the drawn roving on the one hand by the effect of the rotation of the beginning of the yarn on the yarn spool 23 by the revolutions of the spindle 19 and on the other hand by the other twists resulting from the number of revolutions n pp of the carrier of the working surface which is higher than the number of revolutions n v of the spool. The condition of the higher twist is present in the section of the yarn 32 built between a clamping grip of the last pair of the rollers 26 of the drawing device 1 and the traveller 12 (Fig.3). In this section the yarn 32 built is guided from a clamping grip of the last pair of rollers 26 by a guiding eyelet 2 along the working surface 5 until it reaches the traveller 12 . The beginning of the section of the yarn built is not directly in the clamping grip of the last pair of rollers 26 since, first, a drawn roving 31 leaves the grip, which is, while being strengthened by the twist, pulled by the twisting into the twisting triangle, in the apex of which the yarn 32 starts to build itself. For the sake of simplicity the insignificant part of the length in the term defining the section of the yarn built is neglected. Downstream of the traveller 12 , through which the yarn 32 built is threaded, the originally more twisted yarn 32 starts to be transformed in such a way that the original excess of twists is lost. The yarn 33 transformed in this way is present in the transforming section of the yarn which begins at the traveller 12 and ends on the yarn spool 23 . The final number Z of twists of the yarn 34 is achieved in the transformed yarn 33 just at the moment of its fixing on the yarn spool 23 . Both the yarn 32 built and the finished yarn 33 are strengthened by additional twist more than desirable for achieving a very high yarn productivity. This productivity can be essentially greater than in the case of top productivities of the ring system and it is not impossible that the spindle can reach the revolutions of 40 000 min -1 or even more, while the yarn 34 has a character of a ring spun yarn and even further advantages in the surface structure which are mentioned below. The choice of the number of revolutions n pp of the carrier of the working surface 6 with respect to the number of revolutions n v of the spool depends on the technological practice in spinning various kinds of fibers to various degrees of yarn fineness, and on the requirement for the final twist properties of the yarn 34 . Only those revolutions n pp be mentioned which the working surface 5 must minimally exhibit with respect to the revolutions n v of the spool so for the spinning process to still work in a satisfactory fashion. This is at least the number of revolutions n pp = n v . [(Z.O min +1)/Z.O min ], where O min is the minimum length of the circumference of the yarn winding on the tube in the region determined for winding the yarn. In this extreme case of the relation n pp >n v the relative revolutions of the traveller 12 n b with respect to the working surface 5 are in the interval 0 to N , where N=n v .[(Z.O min +1)/Z.O min ]-[(Z.O max +1)/Z.O max ]>1 and where O max is the greatest circumference of the yarn winding 34 on the yarn spool. It is obvious from what has been said that even in the case of the relation of the minimal difference between n pp and n v within the limit terms, practically everywhere in the process of forming the winding of the yarn 23 on the spool tube 22 , in particular on a conical one, a relative movement of the traveller 12 with respect to the working surface 5 is ensured. This is evidently true also for any other guiding member, as for example the eyelet 14 of the carrying member 15 (Fig.5). The relative movement of the traveller 12 or that of the eyelet 14 is accompanied also by a relative movement of the formed yarn 32 not only across the working surface away from its edge 9 adjacent to the drawing device 1 towards the edge 8 , but also by a relative movement along the circumference of the working surface 5, which conveniently acts on the yarn 32 built. The circumferential movement of the formed yarn reduces the contact with the working surface 5 and, consequently, also reduces the level of the reaction friction force opposed to the movement of the transversally drawn yarn 32 . The circumferential movement at the same time rounds off the surface of the yarn 32 to be formed and usefully reduces its hairdness. In certain conditions, in particular in the case of increased difference between n pp and n v , there even occurs a partial rolling of the yarn which additionally temporarilly strengthens the yarn 32 built in particular in the part of the section of the formed yarn between the clamping grip of the last pair of rollers 26 and the guiding eyelet 2 . Consequently it is obvious that the apparatus for carrying out the method according to the invention conveniently utilizes an aggregation of known and of completely novel elements for obtaining a clearly higher technological effect, residing in the high speed of formation of the yarn 34 having a substantially ring spun character. For example, in a variant (Fig.3) the yarn 32 formed with an increased twist is supported against an excessive buckling away from the rotation axis of the spindle by the working surface 5 , whereby any extreme increase of centrifugal forces by balooning is inhibited and from the rotating guiding eyelet 2 the yarn is guided outwardly from the rotation axis, which means that in its loading tensioning forces only are involved. The level of the tensioning forces depend on the level of the reaction friction force in particular on the working surface 5 . To this end the means for obtaining a reduced friction coeficient of the yarn built have been previously described, while its circumferencial relative movement along the working surface 5 yet reduces this level in a convenient way. It is consequently possible to ensure with such an arrangement a satisfactory spinning process even with spindle revolutions of 50 000 min -1 . It is understood that the technical means for a constant rotation of the carrier 6 of the working surface 5 in connection with the constant rotation of the spindle 19 are known from the state of the art. Even with a high speed of the carrier 6 of the working surface there is no risk of the traveller flying away, subject to an efficient construction (Fig.4) being provided, where the traveller is applied to the carrier by a centrifugal force and a tensional force of the yarn, opposed to the centrifugal force, and is released so that no excess wear is caused. The spinning process can be started by spinning-in, which can be carried out as follows: The spindle 19 , together with the yarn 23 , is stopped and is moved to the lower position (Fig.1, dotted lines). The operator or the automatic system finds the end of the yarn 34 and threads the necessary end 34 of the yarn through the traveller and through the whole cavity of the standing carrier of the working surface 5 , and at the same time, through the guiding eyelet 2 in a variant (Fig.3), or, subsequently, through the eyelet 2 in another variant (Fig.4), where it is possible to simply thread the yarn in. The threading of the yarn 34 can be carried out, for example, by a threading needle. The threaded yarn is adapted in length after the spindle 19 with the yarn spool 23 has been returned to the operative position (Fig.1) in such a way that in the section of formation of the yarn said yarn is looser in order to equalize the force effects on the yarn 34 , which is not strengthened by an excess of twists at the spinning-in instant. During the entire handling time the drawn roving from the clamping grip of the last pair of the rollers 26 of the drawings device 1 is sucked away by means of a displaceable sucking nozzle 35 (dashed line in Fig. 2) into a container of recuperable waste fibres. However, as soon as the yarn 34 has been supplied by a current way, used in ring spinning, on the outcoming drawn roving, the rotation of the carrier 6 of the working surface and of the spindle is restored in the required relation n pp >n v . In this way the process of spinning has been started. The looser yarn 34 in the section of the yarn being built is not loaded by tension in a standard fashion, while in the meantime a reserve of yarn 32 being built and of the transformed yarn 33 is formed. The described method also applies to a case of a yarn break and of a function renewal of the spinning process. To simplify the steps, the machine is provided with sensors of the state of spinning, which, after a yarn break, stop both the carrier of the working surface 5 and the spindle 19 , or will also safeguard that the spindle rides down to the lower position to find the yarn beginning. Thereafter said means will restart the operation of the working surface 5 and also of the spindle 19 after having introduced the yarn into a certain space, where it is normally operatively present, either in a spontaenous fashion or after an impulse of the operator, either manual or automatic. It is understood that it was not possible to cover by the description of the exemplary embodiment all the embodying possibilities of the method according to the invention. List of reference numerals (1) drawing device (2) guiding eyelet (3) strengthening and guiding device (4) winding device (5) working surface (6) rotating carrier (7) guiding member (8) edge of the working surface remote from the the drawing device (9) edge of the working surface adjacent to the drawings device (10) conical part of the working surface (11) cylindrical part of the working surface (12) traveller (13) orbital path (14) eyelet (15) carrying member (16) sliding bearing (17) rolling or aerostatic bearing (18) belt (19) spindle (20) bench (21) double arrow (22) spool tube (23) yarn spool (24) individual electromotor (25) machine frame (26) last pair of rollers of the drawing device (27) roving (28) roving spool (29) fiber sliver (30) sliver can (31) drawn roving (32) yarn being built (33) transformed yarn (34) yarn (35) suction nozzle

Claims: A method of production of yarn by the way of continuous spinning from a fiber sliver, comprising a step of drawing the sliver to the form of a drawn roving (31) having the yarn fineness and strengthened by a twist obtained by rotation of the yarn beginning together with the yarn spool (23) which is wound-up on a spindle (19) and a step of centrally guiding the yarn being produced by a guide means (2) before its entry on a working surface (5) of a rotating carrier (6) for guiding the yarn by the effect of centrifugal and tensional forces until reaching a guiding member (7) arranged at its edge and carried by the working surface (5), by which the yarn is guided during its transport out of contact with the working surface for being wound on the rotating spool (23), the axial position of which with respect to the edge of the working surface (5) is changing during the winding-up, characterized in that the yarn circles during the guiding along the working surface (5) of the carrier (6) and the carrier (6) is rotated with a higher number of revolutions than the spool (23), whereby an additional twist is formed on the yarn between a drawing device (1) and the guiding member (7). A method according to claim 1, characterized in that the carrier (6) must exhibit at least the number of revolutions n pp = n v [(Z · O min + 1)/Z · O min ], where n v is the number of revolutions of the spool, Z is the number of the twists inserted into one meter of the yarn being built and O min is the minimum length of the circumference of the winding of the yarn on the spool tube. An apparatus for carrying out the method according to claim 1 or 2, comprising a drawing device (1), an eyelet (2) centrally arranged relative to the axis of a spindle (19), a rotating carrier (6) having a working surface (5) surrounding the spindle (19) and carrying at the edge of the working surface (5) remote from the drawing device (1) a guiding member (7) for an independent movement along the circumference of the working surface (5) and a device (20) for setting the mutual axial position of the edge of the working surface (5) and of the spindle (19), characterized in that the rotating carrier (6) is motionally coupled with respect to the spindle (19) such, that the rotating carrier (6) has a higher number of revolutions than the spindle (19) for forming an additional twist on the yarn section between the drawing device (1) and the guiding member (7). An apparatus according to claim 3, characterized in that the carrier (6) must exhibit at least the number of revolutions n pp = n v [(Z · O min + 1)/Z · O min ], where n v is the number of revolutions of the spool, Z is the number of the twists inserted into one meter of the yarn being built and O min is the minimum length of the circumference of the winding of the yarn on the spool tube. An apparatus according to claim 4, characterized in that a mechanical coupling is provided between the drive of the carrier (6) of the working surface (5) and the drive of the spindle (19). An apparatus according to claim 4, characterized in that an electronic coupling is provided between the individual electro-drive of the carrier (6) of the working surface (5) and the individual electro-drive of the spindle (19).

Inventors: DIDEK STANISLAV DIPL-ING, MAIXNER VACLAV, STEJSKAL ALOIS DIPL-ING, DIDEK, STANISLAV, DIPL.-ING., MAIXNER, VACLAV, STEJSKAL, ALOIS, DIPL.-ING., Maixner, Václav
Applicants: VYZK USTAV BAVLNARSKY, VYZKUMNY USTAV BAVLNARSKY
Application year: 1991
Main classification: D01H1
IPC codes: D01H1