Title of Invention

APPARATUS FOR WINDING A THREAD ONTO A BOBBIN

Abstract

ABSTRACT AN APPARATUS FOR WINDING A THREAD ONTO A BOBBIN (1868/MAS/97) An apparatus for winding a thread (F) onto a bobbin (3), having a thread guide (7), which is connected to a traversing element (8) operating by means of a motor-drivable driving wheel (12) and guide pulleys (9, 10) and executes a traversing motion in a longitudinal direction of the bobbin (3), and having a sensor (13) serving as a position pickup for monitoring the traversing motion of the thread guide (7), characterized in that the traversing element (8) is guided by means of a preloading organ (12) spring-mounted at right angles thereto for compensating tension variations.

Full Text

The present invention relates to an apparatus for winding a thread onto a bobbin, having a thread guide, which is connected to a traversing element operating by means of a motor-drivable driving wheel and guide pulleys and executes a traversing motion in a longitudinal direction of the bobbin, and having a sensor acting as a position pickup for monitoring the traversing motion of the thread guide. Owing to the high accelerations and decelerations of the traversing element, said element is to have as low a mass as possible and therefore preferably takes the form of a flexible organ rigid in traversing direction for transmitting tensile forces. Suitable, known traversing elements are, for example, strings, wires, cables, bands or belts. In a winding apparatus of said type described in EP-A-0 453 622, in which the traversing element is formed by a string, the guide pulleys and the string are disposed rigidly on a common carrier plate. Upon each reversal of motion of the thread guide and hence of the string, one of the two strands of the string running from the thread guide via the guide pulley to the driving wheel is tightened and the other is slackened, thereby impairing the positioning accuracy of the thread guide and limiting the traversing speed. The object of the invention is therefore to indicate a winding apparatus, with which said dynamic variations of the traversing element in the form of a flexible organ in the manner of a string, belt, cable, band or the like no longer occur in the region of the reversing points so that a very high traversing speed and a likewise very high positioning accuracy of the thread guide is achieved. driving wheel on the tongue-like bracket connected to the carrier by bending supports has the advantage that it is possible by suitably dimensioning and designing the bending supports to achieve an optimum dynamic characteristic of the preloading element for the respective machine configuration. A third preferred embodiment is characterized in that a base plate is provided, which is connected, preferably screwed, to the carrier and on which the bending supports act, and that the bracket at one edge is supported by the bending supports and at the other edges is free. A fourth preferred embodiment is characterized in that the base plate has two oppositely directed, U-shaped recesses, which embrace one another and of which the inner recess separates the bracket from the bending supports and the outer recess separates the bending supports from the base plate, and that the bending supports extend between the longitudinal limbs of the recesses from the bracket to the base plate. A further preferred embodiment of the winding apparatus according to the invention is characterized in that the sensor for the traversing motion of the thread guide monitors an rotating organ coupled to the thread guide and scans markings provided on said organ. The rotating organ is preferably formed by the driving wheel or by a disc rigidly connected to the driving wheel. The sensor design according to the invention has the advantage that the sensor from the number of scanned markings always knows the precise position of the thread guide so that the drive motor may be adjusted by a controller always to the rotational speed corresponding to the relevant position. Thus, the output of the drive motor which is formed by a stepping motor may be almost fully utilized. Accordingly the present invention provides an apparatus for winding a thread (F) onto a bobbin, having a thread guide, which is connected to a traversing element operating by means of a motor-drivable driving wheel and guide pulleys and executes a traversing motion in a longitudinal direction of the bobbin, and having a sensor serving as a position pickup for monitoring the traversing motion of the thread guide, characterized in that the traversing element is guided by means of a preloading organ spring-mounted at right angles thereto for compensating tension variations. There follows a detailed description of the invention with reference to an embodiment which is illustrated in the drawings; with reference to the accompanying drawings in which, Fig. 1 a diagrammatic view of a winding head of a bobbin winding machine, from the viewpoint, of an operator, Fig. 2 a view in the direction of the arrow II of Fig. 1; and Fig. 3 a detail of Fig. 2. The winding head shown in Fig. 1 substantially comprises a motor-drivable spindle 1 for receiving and supporting a bobbin case 2, onto which a bobbin, e.g. a cross-wound bobbin, is wound, and a winding advance device 4 for a thread F which is drawn off a supply coil by feeder rolls (not shown). The cross-wound bobbin 1 rests along a surface line against a freely rotatable roller 5 which is mounted on a suitable carrier part 6 of the bobbin winding machine. The winding advance device 4 used to produce the desired winding has, as its central element, a thread guide 7 which executes an oscillating traversing motion along the axis of the bobbin 3, i.e. at right angles to the drawing plane. According to Fig. 2, the thread guide 7 is fastened on a traversing element 8. The latter takes the form of a flexible organ rigid in traversing direction for transmitting tensile forces and is formed, for example., by a string, wire, metal cable, flat belt, toothed belt or V-belt, metal band, chain or the like. The traversing element 8 runs via two guide pulleys 9 and 10, which are rigidly supported on the carrier part 6, to a driving wheel 12 drivable by a motor 11, preferably a stepping motor, is wrapped a plurality of turns around the driving wheel and fastened by both ends to the driving wheel. When the driving wheel 12 is being driven, depending on its direction of rotation the thread guide 7 is moved towards one or the other guide pulley 9 or 10. The distance between the guide pulleys 9 and 10 indicates the maximum possible travel of the thread guide 7 during its traversing motion. The driving wheel 12 is so adapted to the torque characteristic of the motor 11 and to the load formed by thread guide 7, thread F and traversing element 8 that an optimum efficiency results. Associated with the motor 11 is a sensor 13 for detecting the rotary position of the driving wheel 12 and hence the traversing position of the thread guide 7. The sensor 13 is a photoelectric sensor, which comprises a transmitting and a receiving diode and scans the motion of a disc (not shown) which is rigidly connected to the driving wheel 12. For said purpose, the disc is provided with suitable, optically scannable markings, e.g. with holes or slots arranged along a circle. The sensor signal is supplied to a controller 14 which checks whether the motor 11 is operating at the speed intended for the respective position of the thread guide 7. Upon variations between actual and setpoint value, the control module 14 passes a corresponding control signal to the motor 11. The number of markings on the disc and their dimension are selected so as to produce, for the travel of the thread guide 7, approximately 1500 positions of the thread guide 7 which may be checked by the sensor 13. The carrier part 6 in the region of the winding advance device 4 has a substantially rectangular opening 15 which is covered, in the direction of the thread F, by a base plate 16. The base plate 16, which is shown in more detail in Fig. 3, has at its longitudinal edges a plurality of holes 17 for receiving fastening screws and is screw-connected in the region of said holes to the edge of the opening 15. Two further holes provided with the reference character 18 are used for passage of the axles of the guide pulleys 9 and 10, which axles are supported in the carrier part 6. The illustrated base plate 16 comprises a strip-like edge region 19 and a tongue-like bracket 20, which at its one transverse edge is connected to the edge region 19 of the base plate 16 and of which the other edges are free. The connection between bracket 20 and edge region 19 is effected by means of two bending supports 21, which act on said transverse edge of the bracket 20 and extend at a distance from and parallel to the longitudinal edges of said bracket in the gap between bracket 20 and edge region 19 up to the opposite transverse edge of the edge region 19. Said arrangement looks as though the two bending supports 21 separate from one another two oppositely directed, U-shaped recesses 25, 26, which are, as it were, inserted one into the other and of which the inner recess 25 separates the bracket 20 from the bending supports 21 and the outer recess 26 separates the bending supports 21 from the base plate 16. The bracket 2 0 of the base plate 16 is therefore spring-mounted on the edge region 19 and through the action of suitable forces is adjustable, namely both in the direction at right angles to the drawing plane and also at right angles to the longitudinal edges of the base plate 16. In its middle, the bracket 20 has a hole 22 provided for non-rotatably receiving a suitable part of the motor 11 (Fig. 1). The motor 11 is fastened to the rear side of the bracket 20 so that the driving wheel 12 projects in a forward direction from the hole 22. The part of the motor 11 held in the hole 22 is designed in such a way that there is an optimum heat transfer from the motor 11 to the bracket 20. ThUS, the brack"*" **n —+-~ -~+- ~«-|,r =>= = onrinn nariri&ir for the driving wheel 12 but also as a cooling surface for the motor 11. The driving wheel 12, for guiding the turns of the traversing element 8, has a groove in the manner of a thread, the turns of which therefore have an inclination relative to the plane defined by the guide pulleys 9, 10 and the driving wheel 12 which corresponds to the pitch. To prevent the traversing element 8, as it runs in and out of the groove, from rubbing against its side walls and becoming worn as a result, the driving wheel 12 is disposed in a slightly inclined manner so that the turns of the groove in the region where the traversing element 8 runs towards and away from the driving wheel 12 lie parallel to the traversing element 8. Said inclined arrangement of the driving wheel 12 is achieved in that the bracket 20, which carries the motor 11, in its longitudinal direction is arranged at an angle of several degrees relative to the base plate 16, which is easy to achieve by means of suitable bearing means between base plate 16 and the transverse edges of the bracket 20. The spring action of the bracket 2 0 is used to compensate dynamic variations of the traversing element 8, preferably formed by a steel cable, in the region of the points of reversal of motion. When the thread guide 7 arrives at a reversing point, then the two strands of the traversing element 8 which are connected to the thread guide behave differently in that, during the braking phase, the - in the direction of motion - front strand is slackened and the - in the direction of motion - rear strand is tightened and, during the acceleration phase, the - in the direction of motion - front strand of the traversing element is tightened and the rear strand is slackened. Said dynamic behaviour of the traversing element 8 limits the positioning accuracy of the thread guide 7 at a given acceleration or deceleration and hence the traversing speed of the thread guide 7 given a preset positioning accuracy of the thread guide 7. Since the positioning accuracy requirements of the thread guide are already very high for cross-wound bobbins and even higher for windings according to any desired lap laws, said dynamic behaviour of the traversing element 8 would noticeably limit the traversing speed and hence the winding speed. By virtue of the described mounting of the motor 11 and the driving wheel 12 on the bracket 20, which is resilient relative to the guide pulleys 9 and 10, the driving wheel 12 acts upon the traversing element 8 like a preloading organ which presses laterally against the traversing element and compensates tension variations of said element. Since each strand of the traversing element 8 is conveyed from the thread guide 7 to the driving wheel 12, said resilient preloading organ acts simultaneously upon both strands of the traversing element 8 and therefore during the acceleration phase and during the deceleration phase prevents both a slackening of the one strand and an over¬tightening of the other strand of the traversing element. Measurements at bobbin winding machines have shown that with a winding advance designed in the described manner at the reversing points an acceleration of up to 3 00 g may be achieved. Owing to the high resolution of the position sensor 13, the positioning accuracy given a bobbin with a length of, for example, 3 0 or 45 cm is 0.2 or 0.3 mm. The sensor 13 offers the major advantage that the scanning of the disc provided with the markings enables a complete monitoring of the entire traversing motion, which with the hitherto standard arrangement of the sensor along the path of the thread guide 7 would be possible only with an unacceptably high outlay. For said reason, what was previously effected was monitoring not even of the entire motion of the thread guide 7 but only of its passage through a specific position, and in the process it was checked whether the motor 11 had possibly skipped a step. Since with said method the instantaneous position of the thread guide was always only roughly known, for the output of the motor 11 a specific safety margin had to be observed so that the motor 11 was unable to operate at the limit of its performance. The sensor 13 refers its monitoring always to a starting position of the thread guide 7, preferably to the zero point of its traversing motion. Adjustment of the sensor 13 is effected in such a way that the thread guide 7 is moved first to the one reversing point and then to the other reversing point, the sensor 13 counting the number of markings corresponding to said travel and from said number calculating the zero point. The sensor 13 therefore knows the number of scanning pulses between the zero point and the reversing points so that, on the basis of said scanning pulses, it is possible at any time to determine the position of the thread guide 7 corresponding to a specific scanning pulse. This in turn enables extremely precise control of the motor 11, the output of which may therefore be fully utilized. As Fig. 3 reveals, the bracket 20 at its free transverse edge, i.e. the left edge in the drawing, has a lug-like projection 23, associated with which is a notch 24 disposed at the adjacent inside edge of the edge region 19 of the base plate 16. The projection 23 and the notch 24 serve as aids for adjusting the initial tension of the traversing element 8. In the state of rest of the base plate 16, which is shown in Fig. 3 and in which the traversing element 8 is not yet mounted or at any rate is not preloaded, the projection 23 does not lie symmetrically relative to the notch 24 but is displaced slightly downwards. The initial tension of the traversing element 8 is then so adjusted that the projection 23 lies symmetrically relative to the notch 24. Projection 23 and notch 24 therefore perform the function of a marking which indicates the position of the bracket 20 in the preloaded state of the traversing element 8. Naturally, some other marking could 4oe used instead. Experience has shown however that, particularly under the conditions prevailing in the textile industry, the marking formed by projection 23 and notch 24 is eminently suitable as an aid for adjusting the initial tension of the traversing element 8. WE CLAIM: 1. An apparatus for winding a thread (F) onto a bobbin (3), having a thread guide (7), which is connected to a traversing element (8) operating by means of a motor-drivable driving wheel (12) and guide pulleys (9, 10) and executes a traversing motion in a longitudinal direction of the bobbin (3), and having a sensor (13) serving as a position pickup for monitoring the traversing motion of the thread guide (7), characterized in that the traversing element (8) is guided by means of a preloading organ (12) spring-mounted at right angles thereto for compensating tension variations. 2. The apparatus according to claim 1, wherein the traversing element (8) is formed by a wire cable, a spring or a belt, and that the preloading organ is formed by the driving wheel (12). 3. The apparatus according to claim 2, wherein the guide pulleys (9, 10) are mounted in a fixed manner on a common carrier (6), and that the driving wheel (12) is supported on a tongue-like bracket (20) carried by bending supports (21). 4. The apparatus according to claim 3, wherein a base plate (16) is provided, which is connected, preferably screwed, to the carrier (6) and on which the bending supports (21) act, and that the bracket (20) at one edge is carried by the bending supports (21) and at the other edges is free. 5. The apparatus according to claim 4, wherein the base plate (16) has two oppositely directed, U-shaped recesses (25, 26), which embrace one another and of which the inner recess (25) separates the bracket (20) from the bending supports (21) and the outer recess (26) separates the bending supports (21) from the base plate (16), and the bending supports (21) extend between the longitudinal limbs of the recesses (25, 26) from the bracket (20) to the base plate (16). 6. The apparatus according to claim 2, wherein the traversing element (8) is wrapped with a plurality of turns around the driving wheel (12), and that the driving wheel (12) has a groove for guiding said turns and is so disposed that in the region where the traversing element (8) runs towards and away from the driving wheel (12) the groove is aligned parallel to the traversing element (8). 7. The apparatus according to claim 4, wherein the drive motor (11) of the driving wheel (12) is fastened on the bracket (20), and that the fastening is such that the bracket (20) acts as a cooling surface for the motor (11). 8. The apparatus according to claims 6 and 7, wherein the bracket (20) is disposed inclined in the direction of the traversing motion relative to the base plate (16). 9. The apparatus according to claim 5, wherein a marking provided as an aid for adjusting the initial tension of the traversing element (8) is provided in the region of the free traverse edge of the bracket (20), and that said marking is preferably formed by a projection (23) disposed at said transverse edge and by a notch (24) disposed at the adjacent edge of the base plate (16). 10. The apparatus according to any one of the preceding claims 1 to 9, wherein a rotating organ to be monitored by the sensor (13) for the traversing motion of the thread guide (7) is coupled to the thread guide, the rotating organ being provided with marks to be scanned by the said sensor. 11. The apparatus according to claim 10, wherein the rotating organ is formed by the driving wheel (12) or by a disc rigidly connected to the driving wheel, and that said disc is preferably formed by a perforated disc. 12. An apparatus for winding a thread onto a bobbin substantially as herein described with reference to the accompanying drawings.

Documents:

1868-mas-1997 abstract duplicate.pdf

1868-mas-1997 abstract.pdf

1868-mas-1997 claims duplicate.pdf

1868-mas-1997 claims.pdf

1868-mas-1997 correspondence others.pdf

1868-mas-1997 correspondence po.pdf

1868-mas-1997 description (complete) duplicate.pdf

1868-mas-1997 description (complete).pdf

1868-mas-1997 drawings.pdf

1868-mas-1997 form-1.pdf

1868-mas-1997 form-26.pdf

1868-mas-1997 form-4.pdf

1868-mas-1997 petition.pdf