Title of Invention

A DEVICE FOR WINDING A YARN ONTO A BOBBIN

Abstract

A bobbin winding machine comprises a yarn displacement device (4.) for winding a yarn onto a bobbin, having a yarn guide (6) drivable in an oscillating manner and having energy storage mechanisms (J.5) for influencing the deceleration and acceleration of the yarn guide (6) during reversal of its motion. The yarn guide (6) is of a finger- like design and mounted on an axis (8) orientated at light angles to the bobbin axis (S), and the energy storage mechanisms (:1.5) are so designed that the influencing of the Deceleration and acceleration of the yarn guide (6) is effected only in a short region of its motion about the reversing point. The energy storage mechanisms (J.5) are fastened on a carrier (J.4.) which is drivable so as to oscillate about the said axis (8) and their position ~s adjustable. Adjustment of the position of the energy storage mechanisms (J.5) is effected by altering the amplitude of the motion of the carrier (J.4). Said design of the yarn displacement dev-ice (4.) enables high acceleration of the yarn guide (6) at its reversing points and a high winding speed and offers the greatest possible freedom as regards the structure of the winding.

Full Text

Device for winding a yarn onto a bobbin The present invention relates to a device for winding a yarn onto a bobbin, having a yarn guide drivable in an oscillating manner and having energy storage mechanisms for influencing the deceleration and acceleration of the yarn guide during reversal of its motiort, In the known winding devices of said type substantially two types of yarn guide are used, those which take the form of a driving means such as a belt, cable or string orientated parallel to the bobbin axis and those which are drivable about an axis disposed at right angles to the bobbin axis and are like a finger or pointer. Energy storage mechanisms may be used with the yarn guides which are drivable so as to reciprocate parallel to the bobbin axis. They take the,form of spring/damper systems, the spring of which is practically loaded and unloaded in each case over a traverse length, thereby limiting the speed of the yarn guides. The energy storage mechanisms are moreover disposed in a stationary manner so that each variation of the traverse of the yarn guide requires a corresponding adaptation of the position of the energy storage mechanisms. The object of the present invention is to indicate a winding device which permits high Accelerations of the yarn guide at the reversing points and offers the greatest possible freedom as regards the structure of the winding. The yarn guide and its■drive are moreover to be inexpensive and enable operation which is as trouble-free as possible. Said object is achieved according ,to the invention in that the yarn guide is of a finger-like design and is supported on an axis orientated at right angles to the bobbin axis, that the energy storage mechanisms are so designed that the influencing of the deceleration and acceleration of the i yarn guide is effected only in a short region of its motion around the reversing point, and that the position of the energy storage mechanisms is adjustable. [ ' i The finger-like yarn guide is, on the one hand, inexpensive and, on the other hand, very easily and effortlessly adaptable to altered bobbin parameters. The short region of influencing of the deceleration and acceleration of the yarn guide leads to a marked increase in the speed of the yarn guide and the adjustability of the position of the energy storage mechanisms allows variations of the traverse of the yarn guide without major mechanical intervention. A first preferred embodiment of the winding device according to the invention is characterized in that from the start of deceleration of the yarn guide up to the reversing point the kinetic energy of the yarn guide is converted into potential energy and after attainment of the reversing point said potential energy is returned to the yarn guide. A second preferred embodiment of the winding device according to the invention is characterized in that the energy storage mechanisms are fastened on a carrier which is drivable so as to oscillate about the said axis. i In a third preferred embodiment of the winding device i according to the invention, adjustment of the position of the energy storage mechanisms is effected by altering the amplitude of the motion of the carrier. By virtue of fastening the energy storage mechanisms on the carrier, the range of influencing of the deceleration and acceleration of the yam guide may be adjusted precisely and easily. The possibility of adjusting the position of the energy storage mechanisms by means of a simple intervention in the geometry of motion of the carrier increases the flexibility of the device to a quite extraordinary extent. Accordingly, the present invention provides a device for winding a yam onto a bobbin, having a yam guide drivable in an oscillating manner and having energy storage mechanisms for influencing the deceleration and acceleration of the yam guide during reversal of its motion, characterized in that the yam guide is a finger-like design and is supported on a shaft orientated at right angles to the bobbin axis, that the energy storage mechanisms are detached from the yam guide and position controllable, and in that the position of the energy storage mechanisms with respect to the yam guide is controllable during operation of the device. There follows 'a detailed description of the invention with reference to an embodiment which is illustrated in the drawings; the drawings show: Fig. 1 a diagrammatic view of a winding head of a bobbin winding machine in a direction parallel to the bobbin axis; and Fig. 2 a view in the direction of the arrow II of Figure 1. The winding head shown in the drawings substantially comprises a motor-drivable spindle 1 for receiving a bobbin case 2, onto which a bobbin 3, e.g. a cross-wound bobbin, is wound, and a device 4 for displacing a yarn F which is drawn off a supply coil (not shown). In Fig. 2, spindle 1, bobbin case 2 and bobbin 3 are not shown and are indicated by a dash-dot line S symbolizing the axis of the bobbin 3. The bobbin 3 is applied along a surface line against a freely rotatable roller 5, which is mounted on a suitable carrier part of the bobbin winding machine. The yarn displacement device 4 used to produce the desired winding has, as its central element, a finger- or pointer-shaped yarn guide 6 which is mounted on a shaft 8 driven by a motor 7. The shaft 8 is orientated at right angles to the bobbin axis S and at right angles to the drawing plane, so that the yarn guide 6 during operation of the winding head executes an oscillating motion in;the plane at right angles to the shaft 8. • , The yarn guide 6 is provided at one free end with a longitudinal slot 9, in which the yarn F is guided. Disposed - in the running direction of the yarn F - upstream of the yarn guide 6 is a guide rail 10 around which the yarn F is partially wrapped. According to the drawings, the yarn F runs from the supply coil (not shown) to ,the guide rail 10 and from there through the longitudinal slot 9 of the yarn guide 6 to the roller 5. The relative position of yarn guide 6 and guide rail 10 and the length of the longitudinal slot 9 are so selected that the yarn F does not touch the bottom of the longitudinal slot 9 while the yarn guide 6 is in motion. It is thereby guaranteed that the yarn course from the guide rail 10 to the bobbin 3 always has the same geometry which, on account of the roller 5, is also independent of the diameter of the bobbin 3. ' The yarn guide 6 is formed by a finger- or pointer-like element fastened to a hub 11., The hub 11 is fixed on the shaft 8 of the motor 7. During operation of the motor 7, ; depending on its direction of rotation the yarn guide 6 is swivelled in one or the other direction. The maximum traverse of said swivelling motion is denoted in Fig. 2 by the reference character H. On account of the guide rail 10, the yarn F during the swivelling motion of the yarn guide 6 is always moved parallel to the bobbin axis S, and the so-called trailing length, i.e. the yarn length from the yarn guide 6 to the bobbin 3, is always of an identical size. The inertia of the motor 7 is adapted to the inertia of the load formed by hub 11,; yarn guide 6 and yarn F in such a way that optimum efficiency is achieved. Associated with the motor 7 is a first sensor 12 for detecting the angular position of the hub 11 and hence the traverse position of the yarn guide 6. The first sensor 12 is a photo-electric sensor, which comprises a transmitting diode and a receiving diode (not shown) and senses the rotation of a disc (not shown) which is rigidly connected to the hub 11. For said purpose, the disc is provided with suitable, optically scannable markings, e.g. with holes or slots disposed along a circular arc. The sensor signal is supplied to a controller 13 which checks whether the yarn guide 6 at a specific instant is situated at its setpoint position. In the event of deviations between actual and setpoint value, the control module 13 supplies a corresponding control signal to the motor 7. The number of markings on the disc and their dimension are so selected that for each traverse of the yarn guide 6 there are enough positions of the yarn guide 6 auditable by the first sensor 12 to produce a neat, closed precision winding. The first sensor 12 refers its monitoring always to a starting position of the yarn guide 6, preferably to the zero point of its swivelling motion. Setting of the sensor 12 is effected by moving the yarn guide 6 first to the one and then to the other reversing point, the first sensor 12 counting the number of markings corresponding to said traverse and on said basis calculating the zero point. The ' sensor 12 therefore knows the' number of scanning pulses between the zero point and the reversing points so that, with the aid of said scanning pulses, the position of the yarn guide 6 corresponding to a specific scanning pulse may be determined at any time. Said last possibility enables extremely precise control of the motor 7, thereby allowing optimum utilization of its output. A further task of the controller 13 is to linearize the, as such, sinusoidal transfer spefed of the yarn. Sinusoidal in i the present context means that the yarn is moving faster in the middle of the traverse motion than at the reversing r^-i nt-.q s^-i d difference is compensated by the controller 13 in that the latter offsets the linear setpoint values of the position of the yarn guide 6 with a sine function. Provided in the region of the.reversing points of the yarn guide 6 are energy storage mechanisms for influencing the deceleration and acceleration of the yarn guide 6 during reversal of its motion. From the start of deceleration, the respective energy storage mechanism converts the kinetic energy of the yarn guide 6 into potential energy, thereby decelerating the yarn guide. At the end of deceleration, as soon as the reversing point has been reached, the stored energy is;returned to the moving system, with the result that the yarn guide 6 is accelerated once more. Theoretically (ignoring friction), the yarn guide 6 is accelerated back up to its original speed without additional energy being required. The energy storage mechanisms are formed by elastic or spring storage elements 15, such as air buffers, magnetic buffers, spring-mounted buffer plates or other suitable storage media, which are mounted on a carrier 14. At the • level of the storage elements 15 the yarn guide 6 has a rib-like projection 16 which, the instant that deceleration begins, encounters and loads the storage element 15. In the acceleration phase after the reversing point, the storage element 15 is unloaded and accelerates the yarn guide 6. i Since the characteristic curve of the motor 7 is known, the drive of the yarn guide 6 may be set in such a way that the respective storage element 15, at the instant when deceleration starts, is positioned at the reversing pcint. Since it is precisely at said instant that the motor 7 starts to brake, two braking torques are effective, the braking torque of the energy storage mechanism and the braking torque of the motor 7. The reverse is true also of the acceleration section. The length of the section over which the energy storage mechanism is loaded depends upon the reversing traverse, which in turn determines the bobbin quality. It is important that the yarn should remain for the same length of time at each point of the bobbin and also not for a longer time at the ends of the bobbin because, otherwise, edge zones develop and become too thick. In practice, the length of the section over which the energy storage mechanism is loaded is around 1 mm. As Figure 2 reveals, the carrier 14 of the storage elements 15 is substantially Y-shaped. This should not however be interpreted as restrictive. Rather, the shape of the carrier 14 is selectable from a wide range and may, for example, alternatively be circular or fork-shaped. The carrier 14, which is mounted in a freely rotatable manner on the shaft 8 of the motor 7, at the ends of its two upward-projecting limbs carries the storage elements 15 and at its downward-projecting limb is connected by a connecting element 17 to a drive 18. During operation of the drive 18, the connecting element 18 executes a reciprocating motion in the direction of the illustrated double arrow P, with the result that the carrier 14 is driven in an oscillating manner about the shaft 8. The size of the traverse of said oscillating motion of the carrier 14 may be set at the drive 18 or at the connecting element )7 using suitable means, e.g. a stepping motor or any linear or circular drive. When said adjusting means are electrical or magnetic and reproducible, any desired traverse profile may be preselected for the winding process. The traverse of the swivelling motion of the carrier 14 defines the traverse of the yarn guide 6, the carrier 14 executing a much shorter traverse motion and hence also being driven much more slowly than the yarn guide 6. It might be conceivable to make the distance between the storage elements 15 precisely large enough for the projection 16 of the yarn guide 6 to encounter the storage elements 15 at the very instant when deceleration begins. In said case, the carrier 14 could remain in a position of rest. When the traverse of the yarn guide 6 is to be longer, the parrier 14 with the said distance between the storage elements 15 would then have to be swivelled in each case slightly outwards and, when the traverse of the yarn guide 6 is to be shorter, said carrier 14 would have to be swivelled in each case slightly inwards. The traverse of the carrier 14 is therefore always the - compared to the traverse of the yarn guide 6 - very short section from the position of rest shown in Fig. 2 to the end position in contact with the rib 16. ,! For monitoring and controlling the motion of the carrier 14, a second sensor 19 is provided which, like the first sensor 12, is connected to the controller 13. The second ; sensor 19 is a position sensor, e.g. a photoelectric sensor, which is capable of sensing the rotation of the carrier 14. To said end, the carrier 14 is provided with ; suitable, optically scannable markings, e.g. with holes or slots. i i The sensor signal is supplied to the controller 13, which checks whether the carrier 14 at a specific instant is situated in its actual position. In the event of a deviation between actual and:setpoint value, the control module 13 supplies a corresponding signal to the drive motor 18 so that the drive of the carrier 14 is decelerated or accelerated. Since the signals of both the first sensor 12 and the second sensor 19 are supplied to the control module 13, in the latter a cross-comparison between the two sensor signals is additionally effected. By said means it Is possible to detect any deviations in the synchronism between the swivelling motions of the yarn guide 6, on the one hand, and of the carrier (14) of the storage elements 15, on the other hand, and the two*motors 7 and 18 may be suitably re-adjusted. The described yarn displacement device 4 has the advantage of achieving a high winding speed and high acceleration of the yarn guide 6 at the reversing points. By virtue of the energy storage mechanisms 15 acting during the deceleration phase and during the acceleration phase in the region of the reversing points, a relatively large amount of energy may be recovered during deceleration and used subsequently for acceleration, leading to low energy consumption. The adjustability of the energy storage mechanisms 15 makes it easy to alter the traverse of the yarn guide 6 and the arrangement of the energy storage mechanisms 15 on the carrier 14 which is drivable in an oscillating manner allows the traverse of the yarn guide 6 to be varied simply by altering the traverse of the carrier 14 and without mechanical adjustment of the position of the energy storage mechanisms 15. With the adjustability of the traverse of the oscillating motion of the carrier 14 using electrical or magnetic and reproducible me&ns, the possibility is created of producing bobbins wound in any desired manner. WE CLAIM: 1. A device for winding a yarn (F) onto a bobbin (3), having a yarn guide (6) drivable in an oscillating manner and having energy storage mechanisms (15) for influencing the deceleration and acceleration of the yarn guide (6) during reversal of its motion, characterized in that the yarn guide (6) is a finger-like design and is supported on a shaft (8) orientated at right angles to the bobbin axis (S), that the energy storage mechanisms (15) are detached from the yarn guide and position controllable, and in that the position of the energy storage mechanisms with respect to the yarn guide is controllable during operation of the device. 2. The device as claimed in claim 1, wherein the energy storage mechanisms (15) are fastened on a carrier (14) which is drivable so as to oscillate about the said shaft (8). 3. The device as claimed in claim 2, wherein adjustment of the position of the energy storage mechanisms (15) is effected by altering the amplitude of the motion of the carrier (14). 4. The device as claimed in claim 4, wherein the energy storage mechanisms (15) are formed by spring or elastic storage elements and are disposed at a mutual distance on the carrier (14), and that the traverse of the carrier (14) corresponds to the difference between the traverse of the yam guide (6) and the position of the energy storage mechanisms (15) in the position of rest of the carrier (14). 5. The device as claimed in any one of claims 1 to 4, wherein the yarn guide (6) at its free end has an elongated slot (9), which is orientated at right angles to the bobbin axis (S) and in which the yarn (F) is guided. 6. The device as claimed in claim 5, wherein disposed - in the running direction of the yarn (F) - upstream of the yarn guide (6) is a guide rail (10) for the yarn (F), and that the geometry of the slot (9) and the arrangement of the guide rail (10) are tuned to one another in such a way that the trailing length of the yarn (F) is constant. 7. The device as claimed in any one of the claims 1 to 4, wherein a first sensor (12) associated with the yarn guide (6) for monitoring the latter's traverse motion and by a controller (13) connected to the first sensor (12) for correcting deviations between the actual and a setpoint speed profile of the yarn guide (6). 8. The device as claimed in claim 7, wherein a second sensor (19), which is associated with the carrier (14) of the energy storage mechanisms (15) for monitoring the oscillating motion of said carrier and is connected to the controller (13), in which a correction of deviations between the actual and a setpoint speed profile of the carrier is effected. 9. The device as claimed in claims 7 & 8, wherein the first and the second sensor (12 and 19 respectively) take the form of position sensors with scan markings, which are provided on the yarn guide (6) and the carrier (14) or on elements coupled thereto. 10. A device for winding a yarn onto a bobbin substantially as herein described with reference to the accompanying drawings.

Documents:

2281-mas-1997- abstract.pdf

2281-mas-1997- claims.pdf

2281-mas-1997- correspondence others.pdf

2281-mas-1997- correspondence po.pdf

2281-mas-1997- description complete.pdf

2281-mas-1997- drawings.pdf

2281-mas-1997- form 1.pdf

2281-mas-1997- form 26.pdf

2281-mas-1997- form 3.pdf

2281-mas-1997- other documents.pdf