WO2007144714A1

WO2007144714A1 - Process and apparatus for operating a yarn deposition member in winding machines

Info

Publication number: WO2007144714A1
Application number: PCT/IB2007/001465
Authority: WO
Inventors: Gian Franco Colombo
Original assignee: Colombo Filippetti S.P.A.
Priority date: 2006-06-09
Filing date: 2007-06-04
Publication date: 2007-12-21
Also published as: ITMI20061122A1

Abstract

The present invention relates to a method for operation of a yarn- guide element in winding machines according to a final law of motion. Advantageously, the method comprises at least a first step for mechanical operation of the yarn-guide element according to an intermediate and/or average law of motion with respect to two predefined laws of motion, and a second supplementary step of fine adjustment of said mechanical operating device to adapt said intermediate and/or average law of motion to said final law of motion.

Description

"PROCESS AND APPARATUS FOR OPERATING A YARN DEPOSITION

MEMBER IN WINDING MACHINES"

*****

FIELD OF THE INVENTION. The present invention relates to a process for movement of a yarn- guide element in winding machines and the relative operating device.

BACKGROUND OF THE INVENTION. In the textile sector, winding machines are used to form yarn cones from small spools or bobbins of yarn obtained with spinning processes. The spools or bobbins, formed in spinning machines, are fed to the winding machines which unwind the yarn from each spool or bobbin and rewind it in cones of greater dimensions. During unwinding of the yarn the relative quality controls are performed, i.e. checks to ensure the yam has the desired characteristics.

Conventionally, the cones of yarn are cylindrical, conical or superconical in shape and are obtained by winding the yam on a roller of a winding machine. The roller is maintained in rotation about the axis thereof and the yam, previously unwound from a spool or a bobbin, is wound on said roller. A specific yam-guide element of the winding machine maintains the yarn orthogonal to the axis of rotation of the roller during winding.

The yarn guide element is operated to move alternatively and parallel to the axis of rotation of the roller, for the entire length of the yam cone to be formed. The combination of the rotational movement of the roller and of the alternate translafional movement of the yarn- guide element ensures that the yarn is deposited on the roller, to form a cone, with a specific cross angle between the turns of yarn. By varying the law of motion of the yam-guide element, with the same rotation speed of the roller, it is possible to modify the characteristics of the cones obtainable.

For example, if the yarn-guide element moves at low speeds, the cross angle is reduced and the turns of yam deposited on the cone are almost parallel, i.e. the cone has a high density of yarn. If the yarn- guide element moves at high speeds, the cross angle is greater and the turns of yarn deposited on the cone are spaced to form a mesh, i.e. the cone has a lesser density of yarn. The variations in the speed of the yarn-guide element at the ends of the yarn cone, i.e. the accelerations of the yarn-guide element at the edges of the relative cone, affect the yarn distribution in these areas. By adjusting the accelerations it is possible to prevent hard edges from forming or the yarn from being deposited imprecisely, causing it to drop. In general, modern winding machines allow variation of the speed of the yarn-guide element and, therefore, of the speed at which the yarn moves along the roller, to obtain cones having different characteristics, for example in shape (cylindrical, conical and superconical), and with yarn distributed on the single cone as evenly as possible. The movement of the yarn, transverse with respect to the roller, is conventionally controlled by adjusting the operating device of the yarn-guide element. For example, to form a cylindrical cone the yam-guide element is operated by the relative device so that the yarn follows a law of motion of the type shown in the velocity/space (symmetrical trapezoidal) diagram below. Velocity

The law of motion exemplified in the graph refers to the formation of a cylindrical cone having a length (gauge) of 160 mm. The yarn is guided at constant velocity (upper horizontal section of the graph) for a length of 140 mm. At the two ends of the cone the yarn is subjected to a deceleration, an inversion of movement and an acceleration in the opposite direction until once again reaching the aforesaid constant velocity. The cycle is repeated continuously until obtaining the cone. The estimated space for inversion of motion of the yarn at the two ends of the cone is 10 mm.

Indicatively, the law of motion that the yam-guide must impart to the yarn (in the transverse movement thereof) to form a conical cone is of the asymmetrical trapezoidal type, as shown in the diagram below.

Velocity

Space

10mm 140mm jiOmm¹ As shown by the graph, the law does not provide for sections with constant acceleration, as at all times the yam is wound on sections of the cone with different diameters. The possibility of varying the law of motion, i.e. varying the strokes, modulus and direction of the vectors of velocity, accelerations, etc., of the yarn-guide element is an important characteristic of winding machines. In particular there is the need to be able to operate the yam-guide element with different laws of motion according to production requirements, to obtain cones having different characteristics, always with the maximum positioning precision of the yarn on the relative cone.

For example, the yarn must be guided with different laws of motion between the beginning and the end of a winding process, due to the increase in the dimensions of the yarn cone which is formed. The variation in the law of motion must be fast, as the yarn is unwound from the spools and wound on the cone at high speeds, for example of 1500 m/minute. In conventional winding machines the yarn-guide element is a translatable support operated by an electric motor, or a cam provided with grooves and operated in rotation by an electric motor. During the winding step, the yarn runs in a groove of the support, for example a ceramic eyelet, or in a groove of the rotating cam. The cam has a substantially cylindrical shape and the grooves, produced on the external surface thereof, extend helically. When the cam rotates, the yarn is guided by the grooves and moves transverse to the roller with the predefined law of motion.

Conventionally, winding machines have exclusively mechanical or exclusively electronic adjustment of the operation of the yarn-guide element to vary the law of motion thereof. For example, the law of motion of the translatable yam-guide is varied by adjusting operation of the electric motor, generally a linear motor, by means of a specific electronic control unit (electronic adjustment). The law of motion of the yarn guided by the rotating cam is varied mechanically by replacing the cam with another cam provided with grooves having a different extension with respect to the grooves of the replaced cam (mechanical adjustment). The systems conventionally used to guide the yarn during winding have a plurality of drawbacks. In the first place, the yarn-guide elements normally used have significant inertia which has a negative influence on the efficacy of the relative operating device. In other words, current operating devices for yarn-guide elements have reached a limit with regard to performances, in terms of flexibility in variation of the law of motion, and with regard to positioning precision of the yarn on the relative cone and to the speed of the winding process.

According to current practice in the textile industry, yam cones have a length of 160 mm and the yam-guide element in winding machines moves with a frequency of up to approximately 28 Hz to cover the entire length of the relative cone, i.e. the yarn performs at the most 28 strokes per second in transverse direction to the roller. Current electronic controls to adjust operation of the yarn-guide element do not allow a further increase in this frequency without negatively influencing the positioning precision of the yarn on the cone. In other words, current electronic controls are not able to efficiently manage further increases in the frequency of the strokes of the yarn, with respect to the values provided for in the current practice, without a decrease in the winding precision of the yarn, or in the possibility to vary, widely, the law of motion of the yarn-guide element, etc.. A further drawback is represented by the fact that when there is an increase in the speed of the yarn-guide element, for example the translation speed of the support or the rotation speed of the rotating cam, this causes an increase in the risks of the guided yarn breaking or being damaged. In particular, the yarn guided by the grooves of the rotating cam is subject to rubbing against the surface of the grooves. When winding speeds are high the yarn is easily damaged. Mechanical adjustments do not allow high flexibility in variation of the law of motion of the yarn-guide element to be obtained either. In fact, although mechanical adjustments allow, for example, the stroke of the yarn-guide element or the travel of the yarn along the axis of the cone to be varied, the variations in the law of motion obtainable are minimum. However, for some time there has been felt the need to provide operating devices of the yarn-guide element that make it possible to obtain an increase in performances with respect to conventional operating devices, while simultaneously ensuring maximum positioning precision of the yarn on the relative cone and maximum flexibility in variation of the law of motion of the yarn-guide element. SUMMARY OF THE INVENTION.

The object of the present invention is to provide a process for movement of the yarn-guide element in winding machines that solves, in a simple and efficient manner, the drawbacks of conventional systems, simultaneously favouring an increase in performances and maximum flexibility in variation of the law of motion of the guided yarn.

Another object of the present invention it to provide an operating and control device of the yam-guide element in winding machines which allows the problems of conventional operating devices to be solved, which is simple to set up and to adjust and which allows high performances and maximum positioning precision of the yarn on the relative cone to be obtained. Yet another object of the present invention is to provide an operating and control device of the yarn-guide element in winding machines that allows the law of motion of the yarn-guide element to be varied with great precision and rapidity. These and other objects are achieved by the present invention which relates to a process for movement of a yam-guide element in winding machines according to a final law of motion, characterized in that it comprises at least a first step of mechanically operating said yarn- guide element according to an intermediate and/or average law of motion with respect to two predefined laws of motion, and a second supplementary step of fine adjustment of said mechanical operation to adapt said intermediate and/or average law of motion to said final law of motion.

The method according to the present invention allows the yarn-guide elements of the winding machines to be operated obtaining increased performances with respect to the performances obtainable with current operating devices. In conventional winding machines the operating mechanism of the yam-guide element is controlled directly, for example by a specific electronic control unit, to operate according to one or more predefined laws of motion, such as a symmetrical trapezoidal law of motion, with low speeds, to form cylindrical cones with a high yam density, and an asymmetrical trapezoidal law of motion, with higher speeds, to form conical or superconical cones with a low yarn density. The method according to the present invention instead provides that the yarn-guide element is moved by the relative operating mechanism according to an intermediate and/or average law of motion with respect to a predefined and standard, for example symmetrical trapezoidal, law of motion, and a further law of motion also predefined and standard, for example asymmetrical trapezoidal. A second supplementary step is provided for fine adjustment of the operating mechanism, in order to vary the intermediate/average law of motion followed by the yarn-guide element and adapt it to a final law of motion, belonging to the family of laws of motion limited or defined by two predefined laws of motion, which make it possible to attain a movement of the yarn-guide element that allows the production of cones having desired densities, shapes and dimensions, i.e. cones having the desired characteristics. Advantageously, the adjustment step of the operating mechanism of the yarn-guide element is not performed within a vast range of possibilities, as is instead the case in current practice, but for example includes controlled variations of the configuration of this mechanism to obtain minimum deviations from the intermediate and/or average law of motion. In this way, the operating mechanism can be expressly designed to move the yarn-guide element according to the intermediate/average law of motion, with the maximum performances possible for the type of mechanism adopted, so that the fine adjustment step can be obtained with simple to set up and inexpensive mechanical and/or electronic control devices. The present invention also relates to an operating and control device of a yarn-guide element in a winding machine, comprising at least a first mechanism to operate said yarn-guide element according to a first law of motion, characterized in that it also comprises at least a second mechanism to operate said first mechanism, said second mechanism being adjustable to modify operation of said first mechanism and vary said first law of motion to reach the final movement desired.

The operating mechanism of the yarn-guide element is preferably a feeler element of a cam. The cam profile is specifically studied so that the yarn-guide element is operated by the feeler according to the aforesaid intermediate law of motion. The cam-feeler coupling precision is high. The cam can rotate at high speeds, operating the yarn-guide element, by means of the feeler, with high speeds and high positioning precision.

Alternatively, the operating mechanism of the yarn-guide element is an articulated quadrilateral which imparts on the yarn guide element the average law of motion between two predefined laws of motion. In general, the operating mechanism can be an articulated system capable of operating the yarn-guide element with the average law of motion. For example, the articulated system can be formed of five or more levers.

The cam and the quadrilateral are in turn operated, for example, by an electric motor. Preferably, the motor is of an electronically controlled type.

Preferably, the yarn-guide element is a rod linked at a first end to the feeler element of the cam or to an arm of the articulated quadrilateral. At the second end thereof the rod is provided with a housing for the yam to be guided, for example a groove. The movement transmitted by the operating mechanism to the rod makes it oscillate parallel to the axis of the roller on which the yam is wound during winding, maintaining the yarn orthogonal to this axis. The rod is designed to have a low inertia, in order to minimize resistance to accelerations. Moreover, the surface of the rod intended to come into contact with the yarn is minimum, smaller than the surface normally provided on a grooved cam, thereby reducing the risks of friction and the risks of breakage of the yarn.

The supplementary adjustment step according to the present invention can be implemented in various ways and provides for fine adjustment of the operating mechanism of the yarn-guide element. According to one embodiment of the device according to the present invention, the operating mechanism, i.e. the cam or articulated quadrilateral, is in turn operated in rotation by a second mechanism. This second mechanism can be a mechanical speed variator or an adjustable electric motor, for example a brushless motor. By adjusting the speed variator or brushless motor, for example electronically, operation of the first operating mechanism is controlled to vary the law of motion transmitted to the yarn-guide element. This configuration allows fine adjustment of the mechanism, imparting minimum variations in speed to the yam-guide element with respect to the intermediate/average law of motion. Through adjustment of the second actuating mechanism the intermediate (cam) or average (articulated quadrilateral) law of motion transmitted to the yarn-guide rod, and consequently to the yarn itself, is modified so that it is adapted to another law of motion, a final law of motion belonging to the family of laws of motion included between two predefined laws of motion. The advantages of the device according to the present invention relate to the efficacy of adjustment. In fact, adjustments of the second actuating mechanism are as small as possible, with evident advantages with regard to precision. In conventional winding machines, adjustments to the operating mechanism of the yam-guide take place over a wide range. On the contrary, in the device according to the present invention adjustments to the second operating mechanism lead to minimum deviations in the law of motion of the yarn-guide rod with respect to the intermediate/average law of motion imparted by the first operating mechanism.

Preferably, adjustments to the second actuating mechanism are performed through electronic control units. In a practical example of embodiment, the control unit is connected directly to the brushless motor or to the adjustable speed variator. The contribution of the electronics in the device according to the present invention is minimum, with evident positive effects with regard to the simplicity of this device, ease of set-up and costs. In conventional winding machines electronic controls have difficulty in guaranteeing the precision of adjustments of the actuating mechanism of the yarn-guide element when the performances required increase, for example for oscillation frequencies of the yarn- guide of over 25 Hz, or for winding speeds of over 2000 m/minute. In the device according to the present invention, the electronic controls are, as much as possible, intended for minimum operations, while the largest contribution in obtaining the desired law of motion (for the yarn-guide element) is provided by the (first and second) mechanical operating mechanisms.

According to another embodiment of the present invention, the first operating mechanism comprises at least one three-dimensional cam and the relative feeler constrained to the yarn-guide element. The second supplementary step of the method according to the invention provides for electronic and/or mechanical adjustment of the position of the feeler with respect to the three-dimensional cam. The three-dimensional cam extends along an axis and has different profiles along this axis. By moving the feeler element along the axis of the cam to intercept different profiles the law of motion transmitted to the yarn-guide rod varies. The new law of motion corresponds to the profile of the cam on the "felt" section. Adjustment of the actuating mechanism is simple. A control device modifies the relative position between the feeler and the cam to obtain the desired law of motion for the yarn-guide element. The control device can be mechanical, electronic, or mechatronic, for example a piston constrained to the three-dimensional cam to move it along the axis thereof, operated electronically.

The process and the device according to the present invention allow greater performances to be obtained in the winding of yarns with respect to the performances that can be obtained with conventional winding machines. In particular, the method and the device of the present invention make it possible to reach high winding speeds, of over 2000 m/minute, high oscillation frequencies of the yarn-guide element, of over 28 Hz for cones of 160 mm in height, and extremely high positioning precisions of the yam on the cones. The intermediate (cam) or average (articulated quadrilateral) law of motion is obtained with a mechanical operating device, specifically designed to provide maximum performances with this law. Fine adjustments, i.e. control of the variations that cause the yarn-guide element to move with a different final law of motion, are performed with simple mechanical and/or electronic devices. The contribution of these control and adjustment devices in obtaining the law of motion desired is minimum. The law of motion that is obtained after adjustment belongs to a predefined family of laws of motion, and represents the final law of motion that must be applied in the specific case. These devices introduce minimum deviations from the intermediαte/αverαge law of motion obtained with a mechanical operating device. In this way it is possible to obtain, with the current technology available for electronic controls or for mechanical actuators, higher performances and winding precision with respect to current practice. The electronics of the device according to the present invention are simple and are not encumbered by the task of having to perform adjustment of the actuating mechanism of the yarn-guide over a wide range. On the contrary, the electronics of the device operate to perform minimum variations in the configuration of the actuation mechanism, with evident advantages with regard to performance.

BRIEF DESCRIPTION OF THE DRAWINGS.

Further aspects and advantages of the present invention will be more apparent from the description below, provided purely by way of a non-limiting illustration with reference to the accompanying schematic drawings, wherein: figure 1 is a schematic view of a winding machine according to the present invention; figure 2 is a schematic front view of the yarn-guide device according to the present invention; figure 3 is a schematic side view of the yarn-guide device shown in figure 2; figure 4 is a perspective view of a detail of the yarn-guide device according to the present invention; - figure 5 is a graph relative to operation of the yarn-guide device according to the present invention; figure 6A is a schematic sectional view of a yarn-guide device according to the present invention, in a first configuration; figure 6B is a graph relative to the device shown in figure 6A; figure 7 A is α schematic sectional view of the yarn-guide device shown in figure 6A, in a second configuration; figure 7B is a graph relative to the device shown in figure 7A; figure 8A is a schematic sectional view of the yarn-guide device shown in figure 6A, in a third configuration; figure 8B is a graph relative to the device shown in figure 8A; figure 9A is a schematic view of a detail of a yarn-guide device according to the present invention, in a first configuration; figure 9B is a graph relative to the device shown in the figure 9A; - figure 1OA is a schematic view of the detail shown in figure 9A, in a second configuration; figure 1 OB is a graph relative to the device shown in figure 1 OA; figure 11 A is a schematic view of the detail shown in figure 9A, in a third configuration; - figure 1 1 B is a graph relative to the device shown in figure 1 1 A. DETAILED DESCRIPTION OF THE INVENTION.

With reference to figure 1 , there is schematically shown a winding machine 1. The machine 1 is fed with spools (or bobbins) 2 of yarn generally produced in a spinning machine. The yarn 3 is unwound from the spools 2 to be subjected to quality controls and, subsequently, wound on a cone 4 of yarn 3 having greater dimensions than the single spool 2. The quantity of yarn 3 wound on a cone 4 is therefore greater than the quantity of yarn 3 wound on a bobbin 2.

Therefore several bobbins 2 concur to feed the yarn 3 to form a cone 4.

To form a cone 4 the yarn 3 is wound on a roller maintained in rotation about the axis thereof. The yarn 3 is fed in a direction substantially orthogonal to the axis of the roller with an alternating movement. During the winding step, i.e. when the yarn 3 is wound on the relative roller, the yarn 3 is guided by a suitably operated yarn-guide element. Figures 2 and 3 show a detail of the winding machine 1. The yarn 3 is being wound on the roller 5 to form a conical cone. The speed of the yarn 3 is high, in the order of 2000 meters per minute. The axis of the roller 5 is indicated with the reference number 51. The winding machine 1 is provided with a yarn-guide device 6 according to the present invention.

The yam-guide device 6 is provided with a yarn-guide element 61 which moves alternatively in the direction X to deposit the yarn 3 on the rotating roller 5. In the embodiment shown, the yarn-guide element 61 is a rod linked to a drive shaft 62 at a first end 63 thereof. The second end 64 of the rod 61 is provided with a groove 65 to house the yarn 3 running towards the roller 5 or cone 4 being formed. Preferably, the yarn-guide rod 61 is made of low density plastic material, to minimize inertia.

In particular, as shown in figure 2, the yarn-guide rod 61 is rotated by the shaft 62 according to an angle a equal, for example, to 60° when the roller 5 has a length of 160 mm. During operation of the yam-guide device 6, the second end 64 of the rod 61 describes an arc of circumference. The yarn 3 moves in the direction X, running in the groove 65 of the rod 61, remaining substantially orthogonal to the outer surface of the roller 5.

When the law of motion with which the yarn-guide rod 61 is operated varies the characteristics of the cone 4 also vary. For example, if the yam-guide rod 61 moves at low speed, the yarn 3 is translated in the direction X with low speed and deposits on the roller 5 in almost parallel turns. In this first case the cross angle between turns is reduced and the cone 4 has a high density of yarn 3. Conversely, for example, if the yarn-guide rod 61 moves at high speeds, the yarn 3 is translated in the direction X with high speeds and deposits on the roller 5 in turns spaced from one another. In this second case the cone 4 has a lesser density of yarn 3.

Accelerations of the yarn-guide rod 61 at the final ends of the path thereof, i.e. at the edges of the relative cone 4, influence the distribution of the yam 3 in these areas. By adjusting the accelerations of the yarn-guide rod 61 it is possible to prevent hard edges from forming or the yarn 3 from being deposited imprecisely on the roller s. The device 6 according to the present invention allows the law of motion for operation of the yarn-guide rod 61 to be varied, in order to move the yarn 3 in the direction X according to the final law of motion required and thereby obtain a cone 4 having the desired characteristics. Figure 4 shows a detail of the operating device 6. The drive shaft 62, to which the yarn-guide rod 61 is coupled, is operated by a first mechanism 7. In other words movement of the yarn-guide element 61 is entrusted to a mechanical operating device 7. In a first embodiment, shown in figure 4, the first mechanism 7 is a cam-feeler system. Alternatively, the first mechanism can be produced as an articulated quadrilateral.

In particular, the first mechanism is provided with a first cam 72 and with a second cam 73 coupled to an input shaft 71. The input shaft is in turn made to rotate by a second mechanism or by an electric motor. The drive shaft 62 is provided with a feeler element 66 having the function of following the profile of the two cams 72 and 73. The rotating movement (in a single direction) of the input shaft 71 is transformed into an alternate rotating movement of the drive shaft 62 and, consequently, into an oscillating movement of the yarn-guide rod 61. According to another embodiment of the device 6, the drive shaft 62 is coupled to the input shaft 71 by means of levers, configured as an articulated quadrilateral.

The profile of the cams 72, 73 or, alternatively, the configuration of the articulated quadrilateral are chosen to move the yarn-guide rod 61 according to an intermediate or average law of motion with respect to two predefined laws of motion. In other words, in the designing stage of the device 6 two "extreme" laws of motion to be taken by the yarn-guide rod 61 are identified, i.e. a "minimum" law of motion and a "maximum" law of motion, for example a low velocity symmetrical trapezoidal law of motion (minimum law) and a high velocity asymmetrical trapezoidal law of motion (maximum law). During operation of the winding machine 1 it must be possible to operate the yarn-guide rod 61 (and consequently the yarn 3) according to any intermediate or average law of motion between the aforesaid two minimum and maximum laws of motion.

Figure 5 refers to a velocity/space graph showing examples of minimum and maximum laws of motion to form a cone 4 having a length of 160 mm. The continuous line corresponds to a symmetrical trapezoidal law of motion to form a cylindrical cone 4. The areas of inversion of the yarn-guide rod are equal to 10 mm. The speed in the section between the two ends is constant and equal to 10.16 m/s. The dashed line corresponds to an asymmetrical trapezoidal law of motion to form a conical cone 4 with a conicity of 5°57'. The areas of inversion of the yarn-guide rod are equal to 10 mm. The speed in the section between the two ends is variable from 6.77 m/s to 13.54 m/s. The profile of the cams 72, 73, or the configuration of the levers of the articulated quadrilateral provided alternatively, are chosen to operate the yarn-guide rod 61 according to an intermediate or average law of motion with respect to the two minimum and maximum laws of motion. In this way the first operating mechanism can be designed to provide maximum performances when the yarn- guide rod 61 is operated according to the intermediate or average law of motion.

The present invention provides for a fine adjustment step of the first operating mechanism. Adjustment allows the law of motion transmitted to the yarn-guide rod to be adapted to comply with the final law of motion to be obtained. In other words, the first operating mechanism, whether this is the system with cams 72, 73 and feeler 66, or an articulated quadrilateral, operates the yarn-guide rod 61 with an intermediate or average law of motion. A second mechanism has the function of varying operation of the first mechanism, acting on the input shaft 71, to adapt the intermediate or average law of motion to the final law of motion desired.

The second mechanism can be of the electronic or mechanical type, or can be a mechanical or electronic device.

According to an embodiment of the present invention, the second mechanism is a brushless motor which directly controls the input shaft 71. The motor (not shown) is in turn controlled by an electronic control and adjustment unit capable of acting on the rotation speed transmitted to the shaft 71. When the input shaft 71 rotates at constant speed, the cams 72, 73 (or the articulated quadrilateral used equivalently) operates the yam-guide 61 by means of the drive shaft 62 according to the intermediate or average law of motion. The control unit acts on the brushless motor to vary the rotation speed of the shaft 71 so as to vary the law of motion of the yarn-guide 61 and adapt it to the final law of motion desired to produce a cone 4 having predefined characteristics. Advantageously, the control electronics are simple to produce and to set up. The operating device 6 does not require complicated electronic components to adjust the law of motion of the yarn-guide 61. The control unit that adjusts the brushless motor has the task of controlling slight variations in the rotation speed of the input shaft 71 to introduce those deviations between the intermediate or average law of motion imparted by the first operating mechanism and the final law of motion desired for the yarn-guide 61. Adjustment of the second operating mechanism is therefore simple with respect to the adjustment conventionally provided for yarn-guide devices according to prior art.

Figures 6A, 7A₁ 8A relate to a second embodiment of the operating device 6 according to the present invention. The second operating mechanism is not an adjustable motor as in the embodiment described above. In this embodiment the second operating mechanism is a mechanical speed variator 8, operated in turn by a conventional electric motor M which rotates at constant speed. The motor M operates the speed variator 8 by means of a belt 10 (coupled to specific pulleys). The speed variator 8 comprises a fixed central shaft 82, provided with three-dimensional cams 83 and 84. The profile of the three- dimensional cams 83 and 84 varies along the axis of the fixed shaft 82. The feeler elements 85 and 86 of the cams 83 and 84 are mounted on two secondary shafts 87, 88 parallel to the fixed central shaft 82. The speed variator 8 is mounted in a housing 81. The housing 81 is made to rotate by the belt 10 about the fixed central shaft 82. The secondary elements 87, 88 are also rotated with respect to the fixed central shaft 82. The feeler elements 86, 87 consequently rotate on the cams 83, 84. The input shaft 71 is constrained to the secondary shafts 87, 88 by means of gears 11. Operation of the device 6 is as follows. The motor ΛΛ operates the belt 10 which rotates the housing 81 of the variator 8. In other words, the housing 81 rotates at the same speed as the motor M. The secondary shafts 87 and 88 rotate about the fixed central shaft 82, while the feeler elements 85 and 86 follows the profile of the cams 83 and 84. The secondary shafts 87 and 88 transmit motion to the input shaft 71 of the first operating mechanism 6.

The rotation speed of the input shaft 71 can be adjusted by modifying the profile of the cams 83 and 84. This is obtained using three- dimensional cams and a mechanical and electronic device 9 which modifies the position of the feeler elements 85, 86 with respect to the cams 83, 84 along the axis of these cams. In other words, the device 9 moves the three-dimensional cams 83 and 84 on the fixed central axis 82, so as to choose the most suitable profile of the cams to adjust the rotation speed of the input shaft 71 of the first operating mechanism. Figure 6A shows the variator 8 in a first configuration, with the feeler element 85 in contact with the cam 83 at a first end thereof and the feeler element 86 in contact with the cam 84 at a first end thereof. The law of motion transmitted to the yarn-guide rod 61 is shown by way of example in the graph in figure 6B. The law of motion is of the symmetrical trapezoidal type to form cylindrical cones 4 of yarn. The adjustment step provides for operation of the device 9, for example an hydraulic piston controlled electronically. Let us consider by way of example the case in which it is necessary to move the yarn- guide rod 61 according to the asymmetrical trapezoidal law of motion shown in figure 6B, to form a conical cone 4 with a low density of yarn 3, or according to the symmetrical trapezoidal law of motion shown in figure 8B, to form a conical cone 4 with a high density of yarn 3. The adjustment device operates to modify the configuration of the second operating mechanism, i.e. the variator 8. In particular, to obtain the law of motion shown in figure 7B the device 9 configures the variafor 8 as shown in figure 7 A, i.e. with the feeler elements 85 and 86 in intermediate position with respect to the relative cams 83 and 84. To obtain the law of motion shown in figure 8B the device 9 configures the variator 8 as shown in figure 8A₁ i.e. with the feeler elements 85 and 86 in forward position with respect to the relative cams 83 and 84, i.e. in contact with the second end thereof. The device 9 acts by advancing or withdrawing the cams 83 and 84 on the central shaft 82.

According to a further embodiment of the present invention shown in figures 9A, 1OA, 1 1 A, the second operating mechanism and the first operating mechanism are incorporated in a single operating mechanism 100. In this embodiment the cams 72 and 73 which transmit motion to the feeler 66 (doubled) constrained to the drive shaft 62 are three-dimensional cams. The feeler 66 is movable with respect to the cams 72 and 73 to intercept different profiles and consequently allow fine adjustment of the law of motion transmitted to the yarn-guide rod 61. In particular figure 9 A shows the feeler 66 (which is double) in contact with a first (proximal) end of the cam 72 and of the cam 73. The profiles of the two cams 72 and 73 in this section are complementary. Figure 9 B shows the law of motion (velocity/stroke) transmitted to the yam 3 with the operating mechanism in the configuration shown in figure 9A. The law of motion followed by the yarn 3 is of the symmetrical trapezoidal type, with a section at constant speed and two inversion sections.

During the adjustment step of the operating mechanism the input shaft 71, on which the cams 72 and 73 are fixed, is translated with respect to the feeler 66. The figure 1OA shows the operating mechanism in a second configuration, with the feeler 66 in contact with a median portion of the cams 72 and 73. With respect to the configuration shown in figure 9A, the shaft 71 has been moved in the direction Y, i.e. along the axis thereof (alternatively the shaft 62 can be moved). The feeler 66 operates on a different profile of the cam with respect to the one shown in figure 9A. The law of motion transmitted to the yarn 3, shown in figure 1OB, is of the asymmetrical trapezoidal type, with maximum speed slightly above 10 m/s. Figure HA shows the operating mechanism in a third configuration, with the feeler 66 operating on the second (distal) end of the cams 72 and 73. The profile of the cams 72, 73 at the portion intercepted by the feeler 66 is such that the yam 3 is moved by the yarn-guide element 61 according to the law of motion shown in figure 1 1 B, of the asymmetrical trapezoidal type, with a maximum speed slightly below 15 m/s.

The process and the device according to the present invention allow greater performances to be obtained in the winding of yarns 3 with respect to the performances that can be obtained with conventional winding machines. In particular, the method and the device of the present invention make it possible to reach high winding speeds, of over 2000 m/minute, high oscillation frequencies of the yarn-guide element, of over 28 Hz for cones of 160 mm in height, and extremely high positioning precisions of the yarn 3 on the cones 4. The intermediate (cam) or average (articulated quadrilateral) law of motion is obtained with the first operating mechanism, without the use of electronic devices. The mechanism is specifically designed to provide maximum performances when the yarn-guide rod 61 is operated with this law. The performances obtainable with this mechanical device are higher with respect to the performances obtainable with conventional devices with direct electronic adjustment.

Fine adjustments of the law of motion of the yarn-guide rod 61 are performed with simple mechanical and/or electronic devices, for example the control unit of a brushless motor that operates the first mechanism, or the hydraulic piston 9 that operates the speed variator 8, etc.. These devices are simple to set up to obtain the desired law of motion with maximum precision. With the method and the device 6 according to the present invention it is possible to obtain, with inexpensive and easy to use electronic controls or mechanical actuators, higher performances and winding precision with respect to current practice. The electronics of the device 6 according to the present invention are simple and are not encumbered by the task of having to perform adjustment of the first actuating mechanism of the yam-guide 61 over a wide range. On the contrary, the mechanical and/or electronic adjustment devices operate to perform minimum variations in the configuration of the operating mechanism, with evident advantages with regard to production and set-up costs and with regard to performances.

Claims

1. Process for movement of α yarn-guide element (61 ) in winding machines according to a final law of motion, characterized in that it comprises at least a first step of mechanical operation of said yarn- guide element (61 ) according to an intermediate and/or average law of motion with respect to two predefined laws of motion, and a second supplementary step of fine adjustment of said mechanical operation to adapt said intermediate and/or average law of motion to said final law of motion.

2. Process as claimed in claim 1 , characterized in that said second supplementary step is performed by electronically and/or mechanically modifying the configuration of the mechanical device (6, 100) that operates said yarn-guide element.

3. Process as claimed in claim 1 or in claim 2, characterized in that said first step is performed by operating said yarn-guide element by means of a mechanical device chosen from a cam (72, 73) and an articulated quadrilateral, or an equivalent articulated system.

4. Process as claimed in claim 2 or in claim 3, characterized in that said mechanical operating device (6) is in turn operated by an adjustable device chosen from a speed variator (8) and an electric motor (M), and said second supplementary step provides for electronic adjustment of said adjustable devices.

5. Process as claimed in claim 2 or in claim 3, characterized in that said mechanical operating device (100) comprises at least a three- dimensional cam (72, 73) and a relative feeler [66) constrained to the yarn-guide element (61 ), and said second supplementary step provides for electronic and/or mechanical adjustment of the position of said feeler [66] with respect to said three-dimensional cam (72, 73).

6. Operating and control device of a yarn-guide element in a winding machine, comprising at least a first mechanism (6) for operation of said yarn-guide element (61 ) according to a first law of motion, characterized in that it also comprises at least a second mechanism for operation of said first mechanism (6), said second mechanism being adjustable to modify the operation of said first mechanism and vary said first law of motion to reach the final movement desired.

7. Device as claimed in claim 6, characterized in that said first mechanism is chosen from a cam (72, 73) and an articulated quadrilateral operated in rotation by said second mechanism.

8. Device as claimed in claim I₁ characterized in that said second mechanism is chosen from a mechanical speed variator (8) and a brushless motor (M), both electronically adjustable to control the law of motion transmitted by said first mechanism to the yarn-guide element.

9. Device as claimed in claim 7, characterized in that said first mechanism comprises a three-dimensional cam and the relative feeler element (66), linked to said yarn-guide element (61 ) to operate the same, and said second mechanism comprises means to vary the position of said feeler element with respect to the three-dimensional cam to intercept different profiles of the cam and control the law of motion transmitted by the feeler element to the yarn-guide element.

10. Device as claimed in any one of the previous claims 6-9, characterized in that said yarn-guide element is an oscillating rod provided, at a first end, with a housing for the yarn to be wound on a cone and linked to said first mechanism at said second end.

11. Winding machine provided with at least one yarn-guide element, characterized in that it comprises at least one operating and control device of said yarn-guide element according to any one of the previous claims 6-10.