Method for the automatic regulation of the thread tension in a bobbin winding machine

Abstract: The present invention relates to a method for the automatic regulation of the thread tension in a bobbin-winding machine, which involves transferring the thread at high speed from a lower pirn to an upper bobbin and this method includes definite ratios between the pressure values of the thread tension device and the winding speed values at every moment of the thread-collection phases.

Description: The invention relates to a method for the automatic regulation of the thread tension in a bobbin-winding machine and this regulation acts on the pre-established winding-speed values, at each moment, in the various thread-collection phases. As is known, winding devices are used in the textile industry to wind the thread onto suitable bobbins, consisting of cylindrical or flat-tapered cross-wound bobbins. These winding devices, known as bobbin-winding machines have the capacity of winding thread at a high speed unwinding it from a lower pirn and collecting it on an upper bobbin in formation (see DE-A-3812449). Some textile processes consist, firstly, in transferring the thread, at the highest possible speed, from one unit to another. For example a thread produced in a spinning machine, particularly a ring spinning machine, is normally wound onto a bobbin. In bobbin-winding there is, in fact, the transfer of the thread (rewinding) from the lower pirn to the upper bobbin, with an unwinding through axial extraction of the thread from the fixed pirn. In this case the thread undergoes elongation and in relation to this elongation a thread tension is established. With the continuous increase in the transfer speed of the thread (thread length transferred in time unit) to reduce production costs, higher and higher tensions are created in the thread, thus producing frequent breakages, which cause a considerable reduction in the operating performance of the bobbin-winding machine and its productivity. Thread breakage occurs in fact under a tension which is greater than the tensile strength of the thread. It is also well-known to experts in the field, that the thread tension must remain substantially constant to ensure that difficulties do not arise during further textile operations of the bobbin, i.e. the objective is always to obtain units of wound thread which are more suitable for subsequent operations such as dyeing, warping, picking, etc... An increase in the bobbin circumferential speed of the wound thread creates a greater thread tension whereas on the other hand a reduction in the circumferential speed produces a lesser thread tension. For this reason the multiplication ratio is preferably made variable in both directions. It is therefore advantageous that the preregulated and prefixed winding-speed values are made to depend on the quantity of thread to be wound onto the single lower pirn, on the degree of fullness of the bobbin in formation and also on the type of thread being wound, and other factors. In traditional bobbin-winding machines, however, there is no possibility of continually regulating the tension of the thread which is being wound onto the bobbin. As a result, the thread itself may undergo excessive pull which can lead to its breakage. For the same reasons also the winding of the thread onto the bobbin will not be regular. The above practical drawbacks are, instead, eliminated by the method to which the present invention relates. This method, in fact, provides an automatic regulation of the tension and this regulation is obtained by the fact that the thread tension is automatically and continuously checked and regulated by the pressing action of thread tension devices; these devices operate on the thread in relation to the pre-established winding-speed values at each moment during the various thread-collection phases onto the bobbin in formation. For the practical embodiment of the method of the invention the pressure of the thread tension devices has opposite values to the variation of winding-speed values of the thread onto the bobbin in formation. According to another practical embodiment of the method of the present invention it is established that the stretches of increasing winding-speed correspond to stretches of decreasing pressure values of the thread-tension devices and the stretches of decreasing winding-speed correspond to stretches of increasing pressure values of the thread-tension devices. In the same way, the stretches of constant winding-speed correspond to basically constant pressure values of the thread-tension devices. These and other operating characteristics of the method, to which the present patent invention relates, can be better understood with the help of the figures in the enclosed drawings, wherein: in fig. 1 the bobbin-winding machine is shown in a schematical front view with the thread-tension devices acting on the thread with pressure values depending on the winding-speed value; fig. 2 shows the graph of the winding-speed along a stretch ranging from zero to standard speed, a stretch of constant standard speed and a slow-down stretch from standard to zero speed. fig. 3 shows the graph of the pressure values on the thread of the thread-tension devices and these pressure values are in relation to the speed values of fig. 2. In the figures, equal elements, or with equal or equivalent functions show equal references. Also in the figures, to clarify the group of parts which are not necessary for understanding the invention, such as operating and functional groups along the thread run, the various support structures of the bobbin-winding machine, the motorization centres and feeding, support and pirn expulsion devices, have been omitted. In the enclosed figures: 1 is the thread which is unwound from the lower pirn 2 and which runs upwards to be wound in crossed coils around the bobbin in formation 5; 15 is a three-phase motor, or similar motor source, which activates, by means of the toothed belt 24, the thread-guide cylinder 7. The latter is the known driving roller which provides both the alternating coming and going movement of the thread 1, and the rotating movement of bobbin 5 in formation until the latter has reached the required diameter of thread; 10 is the control block based on a miniprocessor, or electronic card suitable for memorizing the operating instructions. More specifically these instructions are inserted by key-board 14 through cable 19. The control block 10 is programmed to transform these instructions coming from cable 19 into a suitable program to be followed in its processing centre to provide, at each moment, the necessary signals for a correct winding. Control block 10 is in fact basically a microprocessor, which uses as input information obtained both from disk-probe 16 by means of cable 18, and the cable of probe 8, which transmits signals programmed for the control of thread 1, which is subjected to exploration by means of block 4, which represents the electronic yarn cleaner, and also from cable 25 which, with its photocell, transmits the presence of the minimum terminal quantity of thread wound onto pirn 2. In relation to said minimum quantity, the photocell of cable 25 when this residue of wound thread is noted, sends an electric signal to control block 10 to establish the driving signals on motor 15, by means of cable 20, to adjust the winding speed to a value which does not damage thread 1 being rapidly wound onto the surface of bobbin 5; there are three thread-tension devices in the known art, in particular clutch components which press, with varying pressure force, thread 1 being wound. More specifically, the pressure variation of the 3 clutch components is activated with electric signals coming from control block 10 through cable 6, and these electric signals preferably activate an electromagnetic activator which pilots and regulates with precise pressure values the action of the 3 clutch components on thread 1, being rapidly wound. The following operational description, with reference to the figures mentioned above, refers to the whole group of devices and components which embody the method of the present invention and the functioning can be easily understood from observing the figures of the enclosed tables. In a textile winding machine, for example in an automatic bobbin-winding machine, thread 1 removed from pirn 2 which is being unwound is collected onto a crossed coil bobbin 5 and in this form it is suitable for use in subsequent operations. As the thread is being transferred from pirn 2 to bobbin 5, the thread itself is subjected to exploration by block 4, which represents the electronic yarn cleaner. When the driving thread-guide cylinder 7 is at a stop, in a resting position, the three-phase motor source 15 is mechanically at a stop and does not receive electrical energy. When the functioning of the driving thread-guide cylinder 7 is required to begin winding the following phases take place: the starting signal is sent, by connecting cable 20 from control block 10, which has the whole operating cycle programmed in its memory. Motor source 15 starts rotating making probe-disk 16 rotate and also the ridge, thread guide roller 7 by means of toothed-belt 24. The speed probe 16 supplies central block 10 through connecting cable 18, at each moment, with the instantaneous speed values which may be in acceleration phase 22, standard phase 21, or slow-down phase 23. The central control block 10 provides, through appropriate elaborations, by means of connecting cable 6, the driving signals to pilot, at each moment, the thread-tension device activator 3, in order to obtain a perfect harmony between the instantaneous speed values of figure 2 and the pressure values of the thread-tension devices 3 of figure 3. In this way it is possible to follow with precision the correspondence of points 9, 11 and 12 and stretches 22, 21 and 23 in both graphs of figure 2 and figure 3. More specifically, the interruption of lines of figure 3 is programmed and memorized, through key-board 14, in the control block 10, and the pressure values on the thread by means of the thread-tension devices 3 are in relation to the corresponding instantaneous speed values shown by probe 16 and transmitted by cable 18 of block 10. The latter, as a central unit having the whole programmed operating winding cycle in its memory, sends preselection signals of accelerations and speeds to be obtained, at each moment, during the whole formation cycle of bobbin 5. The central block 10 compares the preselection signal sent to motor source 15 with the instantaneous speed value sent from probe 16 and, with appropriate elaborations, supplies, through cable 6, signals of the correct functioning of the activator of the thread-tension devices 3 which are pressing on the thread in a value which depends on the winding speed of the thread itself 1. A description has been given of a preferred embodiment with some variations. It is evident however that other forms of embodiment are possible which enter into the spirit and scope of the present invention. In this way, as the activating devices may vary so is it also possible to combine or remove operating units on the single or group of winding stations to advantageously co-ordinate the all the units in the various operating and control phases of the relation between the pressure values of the thread-tension devices 3 and the winding speed values. These and other variations are consequently possible without leaving the range of the invention.

Claims: Method for the automatic regulation of the thread tension in a bobbin winding machine having a lower pirn (2), an upper bobbin (5), and a thread tension device (3), comprising the steps of: collecting the thread (1) unwound from said lower pirn (2) on said upper bobbin (5) in formation; pressing on the thread (1) by said thread-tension device (3) between said lower pirn (2) and said upper bobbin (5), characterised by further comprising the step of controlling a pressure action on said thread (1) by said tension devices (3) on the basis of the winding speed value during an entire period of thread collection on the bobbin (5). Method according to Claim 1, characterised in that said pressure action is controlled such that a pressure value by said thread-tension device (3) increases in accordance with a decrease of said winding speed value and decreases in accordance with an increase in said winding speed value. Method according to Claim 2, characterised in that said pressure action is controlled such that stretches of decreasing pressure value of said thread-tension devices (3) correspond to stretches of increasing winding speed and stretches of increasing pressure value of said thread-tension devices (3) correspond to stretches of decreasing winding speed. A method according to Claim 1, characterised in that said pressure action is controlled such that stretches of decreasing pressure value of said thread-tension devices (3) correspond to stretches of increasing winding speed and stretches of increasing pressure value of said thread-tension devices (3) correspond to stretches of decreasing winding speed. Method according to Claim 1, characterised in that stretches of constant winding speed correspond to stretches of constant pressure value of said thread-tension devices (3).

Inventors: BADIALI ROBERTO, BERTOLI LUCIANO, MARANGONE NEREO, BADIALI, ROBERTO, BERTOLI, LUCIANO, MARANGONE, NEREO
Applicants: SAVIO MACCHINE TESSILI SPA, SAVIO MACCHINE TESSILI S.P.A.
Application year: 1995
Main classification: B65H59
IPC codes: B65H59