Abstract:
A process and apparatus for the winding of a thread onto a reel. 
     A thread is guided by a thread guide fastened to a cord. 
     The cord is driven by a drive part, which, under the action of a transfer roller engaging in a slot, executes a harmonic oscillation. A transfer roller is attached to a disc-shaped bearing part, driven by means of a driving wheel, and can, for changing the amplitude of the harmonic oscillation, be displaced in the radial direction by utilizing an electric motor. For the purpose of approximating the thread guide movement to a triangular oscillation, a heart-shaped compensating disc, likewise driven by the driving wheel, sets a carriage in oscillating movement synchronous to the harmonic oscillation, so that, due to displaceable pairs of rollers, which are mounted on the carriage and via which the cord is led, as also via fixed rollers lying between successive displaceable rollers, in each case the path of the cord is lengthened on one side of the traversing interval and correspondingly shortened on the other side.

Description:
This is a continuation application of Ser. No. 07/710,028, filed Jun. 3, 1991, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to an apparatus for the winding of a thread onto a reel. 
     2. Discussion of the Prior Art 
     A general process for the winding of a thread onto a reel is discussed in European Patent No. EP 0 113 784 A1, in which the cord to which the thread guide is fastened is passed via fixed deflecting rollers, arranged on both sides of the traversing interval, and a drive roller, the direction of rotation of which must be reversed as abruptly as possible when the thread guide movement reaches a reversal point. This solution requires that the drive roller, which in the interests of continuity of the thread guide movement between the reversal points should have a relatively great moment of inertia, is subjected to a very high angular acceleration, which according to the cited document is achieved by transferring the kinetic energy of the drive roller and of the parts at least frictionally connected to it to rotationally suspended flywheel masses, which return the rotational energy imparted to them back to the drive roller once the thread guide has passed through the reversal point. Since the energy transfer from the drive roller to the respective flywheel mass begins with an acutely angled collision, which requires a precise adjustment of parts of relatively high mass subjected to high forces, it is to be feared that the long-term stability of the apparatus is precarious, even with considerable expenditure on the structural design. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to provide an apparatus of the generic type in which, the movements in particular of parts of relatively high mass are as continuous as possible and do not require any high accelerations or angular accelerations. 
     The present invention is directed to, an apparatus having thread guide movement together with the required rapid reversal at the reversal points is produced by superimposing simple movement sequences which can be derived from smooth rotational movements. 
     Further, the apparatus has smoothly rotating parts which drive oscillating parts, the messes of which can be kept small and the displacements of which are, in part, greatly shortened by additional measures, which also correspondingly reduces the accelerations to which they are subjected. 
     This results in general in continuous movement sequences, in which virtually only the thread guide and the cord driving it--both parts of low mass--are subjected to the high accelerations unavoidable here, whereas more complicated mechanical parts also of higher mass are in all cases subjected to only relatively low accelerations. As a result, a high life time of the apparatus and low requirements of the same with respect to servicing, in particular readjustment, are achieved without great expenditure on structural design. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is explained below with reference to drawings just representing ways of carrying it out, in which: 
     FIG. 1a shows in diagrammatic representation a first embodiment of an apparatus according to the invention 
     FIG. 1b shows in diagrammatic representation a second embodiment 
     FIG. 2 shows the deflection of the thread guide as a function of time according to the invention as well as its split into a fundamental component and a complementary component, and 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The apparatus represented in FIG. 1a has a thread guide 1, which is fastened to a cord 2, which runs via rollers 3a, 3b, which laterally bound the traversing interval over which the position of the thread guide 1 can vary. A motor 4 drives via a driving wheel 5 a drive apparatus 6, which for better understanding of its function is shown swung into the plane of the Figure in relation to its actual position with respect to the driving wheel 5. 
     According to the invention, the drive apparatus 6 has a displaceable drive part 7, to which the ends of the cord 2 are fastened and which is provided with a slot 8, aligned perpendicularly to the direction of movement of the said drive part. Rigidly connected to the driving wheel 5 by a shaft 9 is an arm 10, which bears a gear wheel 11, which is in engagement with a gear rim 12. The diameter of the gear wheel 11 is half the diameter of the gear rim 12. It bears in the region of its periphery a transfer roller 13, which protrudes in the axial direction and engages in the slot 8 of the drive part 7. Normally, gear rim 12 is kept in a fixed position during the winding operation; however, the gear rim 12 is rotatable about its axis, which coincides with the center line of the shaft 9, by means of a motor (not shown) or by hand rotation. The gear rim is connected to a pulley 12a by means of a belt 12b. The motor rotates or drives the pulley 12a, which by means of the belt 12b causes rotation of the gear rim 12. 
     Likewise shown as swung into the plane of the Figure for better understanding is a compensating apparatus 14, having an approximately heart-shaped compensating disc 15, the centre point of which is rigidly connected via the shaft 9 to the driving wheel 5 and the arm 10 and the diameter of which through the centre point is angle-independent in the sense that the diameter of the disc 15 remains the same regardless of the position of the disc 15, thereby ensuring a constant contact between the disc 15 and the rollers 17a and 17b. A carriage 16 contacts the compensating disc 15 by means of contact rollers 17a, 17b at mutually diametrically opposite points of the periphery of the said disc. It is mounted displaceably along the line adjoining said contact points and bears at each end a pair of rollers, referred to hereinafter as displaceable rollers 18a, 18b, 18c, 18d. 
     To the left of the traversing interval, after the roller 3a, the cord 2 runs via a deflecting roller 19a, then via the first displaceable roller 18a, a fixed, i.e. not fastened to the carriage 16 but connected to the housing, roller 20a, on via the second displaceable roller 18c and via further deflecting rollers to the drive part 7. To the right of the traversing interval, the relative arrangements are analogous. 
     The fixed rollers 20a, 20b are not fastened directly to the housing but in each case to a pivotally suspended lever 21a, 21b, which on one side of the pivot point bears the roller, whereas on the other side there acts a spring 22, which is stretched between the two levers 21a, 21b. The levers are also connected by a rod 23, which is pivotally anchored to the lever 21a on the side of the pivot point which bears the roller 20a and in the case of the lever 21b on the side which is opposite the roller 20b, to be precise at the same distance from the pivot point as on the lever 21a. 
     The apparatus described functions as follows: 
     The arm 10 is set in a smoothly rotating movement by the motor 4, via the driving wheel 5 and the shaft 9. The gear wheel 12 normally stays at rest during operation. Owing to the rotation of the arm 10, the gear wheel 11 in engagement with the gear rim 12 also rotates, to be precise--as known from kinematics--in such a way that the transfer roller 13 fastened at its periphery executes a harmonic oscillation, sweeping over a diameter of the gear rim 12, the component of this oscillation which is parallel to the direction of movement of the drive part 7 being transferred by the engagement of the transfer roller 13 in the slot 8 to the drive part 7 and consequently to the cord 2. The angular position of the diameter swept over by the transfer roller 13 can be varied by also turning the gear rim 12 during the winding operation. The rotation of the gear rim 12 as described above is slow compared to the rotation of the arm and should not exceed 90 degrees as explained above. The gear rim 12 can be mounted, for example, on a wheel which is rotatable about an axis coinciding with the center line of the shaft 9. In the position represented in FIG. 1a, the diameter swept over lies parallel to the direction of movement of the drive part 7, which corresponds to a maximum amplitude of the harmonic oscillation transferred to the same. If said diameter includes a certain angle with said direction of movement, the amplitude of the oscillation of the drive part 7 corresponds to the maximum amplitude multiplied by the cosine of this angle. If the angle reaches 90°, the amplitude accordingly drops to zero, the movement of the transfer roller 13 runs parallel to the slot 8 and normal to the direction of movement of the drive part 7. 
     Basically, changing the position of the gear rim 12 by rotation causes a rotation of the gear wheel 11 in the same direction. As the gear wheel rotates, the transfer roller 13 changes position as previously described; accordingly, when the gear rim 12 is rotated, the position of the transfer roller 13 changes as well. Normally, the motion of the transfer roller 13 is a superposition of the motions of the center of the gear wheel 11 and the gear wheel&#39;s 11 rotation. In rotating the gear rim 12 a given angle, the phase relationship between the gear wheel 11 and the transfer roller 13 is changed thereby leading to a rotation of the line along which the transfer roller 13 rotates by the same angle. 
     FIG. 2 shows one half-cycle of thread guide motion, that is, its motion from the middle of the deflection interval to one of the reversal points and back. 
     At a certain mean amplitude, the movement of the thread guide 1 would proceed as represented in the dashed curve in FIG. 2 if it were induced exclusively by the harmonic oscillation of the drive part 7. However, such a harmonic oscillation of the thread guide 1 is not desired, rather it is to execute a movement corresponding to the solid line in FIG. 2, i.e. an oscillation movement which comes as close as possible to being represented by a triangular curve which hereinafter will be referred to as a triangular, oscillation, at constant speed between two reversal points with instantaneous reversal of direction at the same. This approximation to a triangular oscillation is achieved by means of the compensating apparatus 14. 
     The compensating disc 15 is rigidly connected via the shaft 9 to the driving wheel 5 and rotates synchronously with the latter and the arm 10. As a result, the carriage 16 is set in an oscillating movement which is synchronous with the harmonic movement of the drive part 7 and which--in the phase represented in FIG. la--due to the corresponding movement of the displaceable rollers 18a, 18c and 18b, 18d, effects a lengthening of the path of the cord 2 between the roller 3a and the drive part 7 or a corresponding shortening between the roller 3b and the same. If the compensating disc 15 is turned through 180°, lengthening and shortening of the path of the cord 2 are interchanged. Due to the block-and-tackle-like constructions, in which the cord 2 is in each case directed between two displaceable rollers 18a, 18c and 18b, 18d via a fixed roller 20a and 20b, respectively, this shortening or lengthening is increased to four times the deflection of the carriage 16. Of course, higher factors can be achieved by higher numbers of displaceable and fixed rollers. As far as the movement of the thread guide 1 is concerned, the harmonic movement effected by the oscillation of the drive part 7 is superimposed by the complementary movement caused by the compensating apparatus 14, which movement is represented by dot-dashed lines in FIG. 2. 
     They add together to give the desired oscillation, coming very close to the triangular curve. 
     Due to the sprung suspension of the fixed rollers 20a20b, temporary elastic and fatigue extensions of the cord 2 are taken up and the latter is kept taut at all times. In this arrangement, the rod 23 prevents the rollers moving asymmetrically with respect to one another and falsifying the thread guide movement. 
     In the case of the apparatus described, the oscillating movement of the thread guide 1 is derived exclusively from smooth rotational movements. Thus, if at all, the rotating parts are subject to slight accelerations exerted on them by the actions of oscillating parts. They can be made to be of any mass and do not limit the speed at which the apparatus can be operated, in particular if the mass distribution of the compensating disc 15 is chosen such that the axis of rotation coincides with a principal axis. The drive part 7 executes a harmonic oscillation and is therefore likewise not subjected to any very high mechanical loads. Apart from the thread guide 1 and parts of the cord 2, where they are in principle unavoidable, only the carriage 16, with the rollers fastened on it, is subjected to high accelerations. However, even these are greatly reduced, since the deflection of the carriage 16 can be kept small thanks to the block-and-tackle-like construction, by means of which the movement of the carriage 16 is transferred to the cord 2. 
     Of course it is not necessary for the fundamental oscillation executed by the drive part 7 and transferred to the cord 2 to be an exactly harmonic oscillation. Rather, what is decisive is that no extreme accelerations occur--even at the reversal points. Harmonic oscillations have the advantage, however, that they can be derived from rotational movements by particularly simple means. A further example of this is described below in conjunction with FIG. 1b. 
     The compensating disc 15 is connected here via the shaft 9 not only to the driving wheel 5 but also to a disc-shaped bearing part 24, which bears an electric motor 25, which can be supplied with current via a sliding contact 26. The electric motor 25 serves to drive a spindle 27, by means of which the transfer roller 13, which is fastened on a carriage 28 displaceable along a radius of the bearing part 24, can be displaced. Otherwise, the apparatus corresponds to that described in conjunction with FIG. 1a. 
     By means of the electric motor 25, the amplitude of the harmonic oscillation executed by the drive part 7 can be adjusted even during the winding operation. In contrast to the design according to FIG. 1a, in this case no phase shifts occur between the harmonic oscillation and the complementary movement caused by the compensating apparatus 14. 
     In the case of both designs described, the amplitude with which the carriage 16 is oscillated is invariable. Therefore, an exact addition of the harmonic oscillation and the complementary oscillation components induced by the compensating apparatus to form a triangular oscillation is possible only at a certain amplitude of the harmonic oscillation. If the chosen amplitude deviates from this, deviations from the ideal form of oscillation also occur.