Individual suction system for a winding unit

Abstract

 A winding unit served by a suction system which provides all the suction services required by the winding unit, in which such a suction system consists of a single suction device which individually equips each winding unit, each suction device being driven with a variable speed rotation rate value by the winding unit to give each time different depression values required by the winding organs.

Description

[0001] The present invention refers to an individual suction device for the winding units that make up the automatic winder.

[0002] In the industry it is very common to manufacture yarns in a spinning stage - typically ring-spinning frames that produces yarn in spools - followed by a subsequent winding stage in which the yarn is unwound from its spool, cleaned from all of its defects and rewound around a package. The winding process is thus carried out in winders linked with spinning machines.

[0003] In order to clarify both the technical problems faced and solved with the present invention as well as its characteristics and its advantages with respect to the prior art, it is described with reference to a winding process carried out in one of the winding units that make up the automatic winder. The winders in fact consist of a plurality of winding units aligned along the front of the machine and equipped with common control and service apparatuses.

[0004] The winding unit is illustrated in its essential components in figure 1, omitting the components of secondary importance for the technical solution that constitutes the present invention. The supply spool 1 is unwound pulling out the thread 2. The thread 2 passes by the unwinding group that comprises organs for guiding the thread 3, the sensor 4 for detecting the presence of the thread and the thread tensioning device 5. Said thread tensioning device generally consists of a pair of washers facing one another and pressing the unwinding thread 2 between them with a regulated and controlled pressure, said thread running between them at high winding speed take up. Along the path, there is also the device 6 for piecing the yarn ends, commonly called splicer, to which the interrupted yarn ends of the thread that needs to be connected by suction pipes 9 and 10 are taken, when the thread is interrupted due to breaking or due to a cut of the yarn clearer 11 that is immediately below the splicer. The wound thread is collected in the package 12, which is set in rotation by the winding drum 13, on which it rests supported with the package support arm 14, at a predetermined and substantially constant linear winding speed take up. The package 12 in rotation draws the thread 2, unwinding it at a high winding speed take up from the spool 1 kept still on a positioning pin 15.
The spool suction pipe 9 on the side of the spool can make the angular movement α that brings the suction hood of the suction pipe itself first to capture the yarn end of the thread 2 from the unwinding group 3, to lift according to the rotation α, bringing the yarn end to the splicer 6. The package suction pipe 10 on the side of the package on the other hand can make the angular movement β that brings the suction hood of the package suction pipe itself first to capture the yarn end of the thread 2 from the package 12, to lower with the rotation β, until it brings the yarn end on the side of the package to the splicer 6.
The suction pipes 9 and 10 are connected to a device for generating depression that, during restoration interventions of the thread 2 continuity between the spool 1 and the package 12, provides for the depression necessary to capture and handle the yarn ends on the side of the spool and on the side of the package.

[0005] The splicer 6, after having received and cut the two yarn ends to the correct size - eliminating the waste and broken portions of thread, the so called "coarse fibers", by making them get suctioned by the suction pipes 9 and 10 - and having correctly aligned such prepared yarn ends, thus continues to carry out their joining. The splicer 6, once the joining has been carried out, releases the thread letting it return into its winding configuration from the spool 1 to the package 12. The winding process substantially consists of unwinding the supply yarn and of its purification from defects in terms of mechanical consistency or size. In its passage from the spool 1 to the package 12, the thread 2 is controlled by the yarn clearer 11 that detects its dimensional defects, both concerning its transverse and length dimensions. The yarn clearer 11 commands the cutting of the thread all the times that the detected dimension of the thread 2 does not enter within the field of acceptable thread dimensions according to its calibration. The cutting device of the thread can be incorporated in the yarn clearer 11 itself i.e., like in figure 1, separate like a knife 7, shown situated between the sensor 4 of the thread and the thread tensioning device 5.

[0006] Following breaking, or cutting of the thread 2 driven by the yarn clearer 11, the yarn clearer itself indicates that there is no thread to the control unit 16 of the winding station. The control unit 16 comprises, amongst its functions, the driving and controlling program for the rejoining procedure, with the connections indicated with a broken line as an example.

[0007] As a general rule, the defects of the thread 2 being processed are due to irregularities or discontinuities in the previous spinning operations and can be localized or distributed along a more or less long portion of thread. Again in general, during the passage in the yarn clearer 11 of a more or less extended defect, the yarn clearer 11 commands the cutting preferably only when the defect has finished and the yarn has returned to its normal size so as to be provided, on the side of the spool, with a yarn end of thread without defects and that is suitable for being joined. Before cutting, on the side of the bobbin, the portion of defective yarn continues to pass in the yarn clearer and to wind around the package 12. The yarn clearer 11 detects and communicates to the control unit 16 the length of the defective portion, before restoring the continuity of the thread through joining, must be suctioned and removed from the yarn wound on the package 12, so as to be provided with a yarn end of thread suitable for being joined on the side of the package as well. The removal of the defective portion wound on the package 12 is carried out by making the winding drum 13 - and with it the package 12 counter-rotate - and by suction the thread with the suction pipe 10 raised against the surface of the package 12, as shown in figure 1, until the length of the counter-rotation of the winding drum 13 corresponds to the length of the detected defective portion.

[0008] The "coarse fibers" that the suction pipes must manage and move away can thus have a considerable length, even bearing in mind that the normal winding speed take up of the thread 2 in the winding path, in current winders, is of the order of 30 m/sec, and that therefore also brief amounts of time between the detection of the defect, command and carrying out the cut in any case correspond to a few meters of yarn.

[0009] At the beginning of each new spool, it is necessary to withdraw the yarn end of the new spool that, in general, has already been positioned in a predetermined position: as a general rule, it is fitted at the top of the tube of the spool. For this purpose the same spool suction pipe on the side of the spool 9 is used.

[0010] During the winding, around the spool 1 being processed, a balloon of thread 2 that rotates at high winding speed take up is formed and a substantial amount of dust, fibers and residues of the hairs of the thread being unwound are generated. Such impurities can cause a considerable disturbance for the sensors situated along the path of the thread 2. In more advanced winder models, such impurities are, in general, removed from the path of the thread with one or more dust suction pipes 20 positioned near to the spool 1 being unwound.

[0011] The amount of dust that develops during the unwinding of the spool depends both upon how advanced the unwinding is and on the linear winding rate. At the beginning of the spool there is less dragging and a lower amount of dust is formed, whereas at the end of the spool there is greater dragging and more dust is formed. The generation of dust also depends upon the linear winding rate, essentially by centrifugal effect.

[0012] As outlined thus far, the winding units that form the winder individually require a substantial suction service both in the steps of restoration of the yarn continuity that has been interrupted and during the normal winding operation for cleaning the path of the thread through removal with the dust suction pipe 20.

[0013] According to the prior art, the continual service for the suction with the dust suction pipe 20, commonly known as "dust removal", requires low head suction, of the order of 50-100 mm W.C. (Water Column), i.e. 500-1000 Pascal, and with flow rates of the order of 50 mc/h, with an hourly energy consumption of the order of 50-70 Wh for each unit.

[0014] The suction service for recovering and handling the yarn ends with the suction pipes 9 and 10 occurs with a variable frequency and with brief durations (around 1-4 seconds for each intervention , but it also requires much higher suction pressure, of the order of 600-900 mm W.C., i.e. 6000-9000 Pascal, so as to give efficiency and safety to the capturing of the yarn ends and to the discharge of the thread waste or "coarse fibers" at the end of the joining in the knotter or splicer 6. The frequency of the thread joining operations while unwinding a spool can vary within very wide limits, according to the quality of the yarn and to the calibration set by the yarn clearer 11.

[0015] In the prior art, such suction services at high and low depression at the winding units that form the automatic winders are generally supplied by one or more centralized high depression suction units for a non-continuous suction service and by one or more centralized low-depression suction units for the continuous suction during the normal winding. These two types of suction devices are connected to the single winding units with a network of both collectors that separately distribute the suction service to the two depression levels, and collectors that receive and filter the discharges.

[0016] In such a plant layout, every winding unit is connected to its general high depression suction header with the interposition of intercepting valves, for example electrovalves, which are only opened for the duration of the suction operations required during its interventions on the yarn ends of the thread, thus taking the needed suction for the amount of time necessary. The distribution of the continuous low-depression suction service, on the other hand, does not normally have intercepting valves and it remains connected to suction service even when the winding unit is not carrying out its normal operation.

[0017] This layout of the collective suction service is not without drawbacks. As an example, long machines are affected by the non uniformity of the suction for the various winding units that form it. Energy consumption for the high depression service, always kept in operation, is considerable. The efficiency of the non-continuous suction is negatively affected when many winding units simultaneously require the service: for example, when a new batch has begun, or when the winder is started up again after stopping. In order to have a reliable operation it is thus necessary to limit the number of winding units that can simultaneously require a high head suction service. Keeping the low-depression suction continuous in all the winding units even during the interventions and in the periods of non operation is a further waste of energy.

[0018] Moreover, it is not possible to vary the suction values of the single winding unit, according to its operation parameters (count of the yarn, advance degree of the bobbin, detection of low capturing efficiency of the yarn ends and of the joining, and so forth). There is not the flexibility that would be advantageous in order to simultaneously operate batches of yarn.

[0019] In the patent EP 662.441 to the same applicant, the continuous low-depression suction service for the dust removal is obtained with individual suction devices for each winding unit, whereas the non-continuous high-depression suction service for the suction pipes for capturing the yarn ends is carried out by a centralized suction device. In the patent application EP 1.950.162 to the same applicant, the continuous low-depression suction service for the dust removal is obtained with a centralized suction device, whereas the non-continuous high-depression suction service for the suction pipes for capturing the yarn ends is obtained with individual suction devices for each winding unit.

[0020] The present invention is aimed at a new suction layout serving the winding units that form a winder that overcomes the drawbacks described thus far of collective suction systems. The present invention, in its most general aspect of suction device which provides all the suction services required by the winding units that form the winder is defined in the first claim. Its variants or preferred embodiments are defined in the dependent claims from 2 to 9. The present invention, in its aspect of improved method of winding, is defined in claim 10. Its variants or preferred embodiments are defined in the dependent claims from 11 to 14.

[0021] The characteristics and the advantages of the suction device serving the winder winding units, according to the present invention shall become clearer from the description of one of its typical embodiments, given as an example and not for limiting purposes, illustrated in figures from 1 to 4.

[0022] Figure 1 illustrates the side view of the winding unit and illustrates the technical problem of the suction service with which it is to be supplied and the suction layout according to the invention. Figures 2A-B, an isometric view and a front view, respectively, show the layout of the suction system of the individual winding unit 23, showing the parallelepiped-shaped bulk. Figures 2C-D, an isometric and sectioned view, respectively, show one improved embodiment. Figure 3 shows an isometric sectioned view of the detail of the filter for "coarse fibers".

[0023] Figures 4A, B, C, D illustrate the characteristics of the performances provided by the suction device according to the present invention during its operation.

[0024] In the technical solution shown in figures 1 and 2 both for the continuous service for the low-depression suction, with the dust suction pipe 20 for removing the dust, and for the high depression non-continuous service, with the mobile suction pipes 9 and 10, an individual suction unit 22 is foreseen, one for each of the winding units 23 aligned along the front of the machine.

[0025] Such a suction unit consists of a rotating suction device with a impeller 25 activated by an electric motor 26 commanded to operate with a speed rotation rate which varies each time according to the necessity of the winding unit. According to a preferred embodiment of the invention such an impeller 25 is a centrifugal impeller.

[0026] According to a preferred embodiment of the invention such a motor 26 is a brushless electric motor driven in frequency by the control unit 16 of the winding unit.

[0027] Such a technical solution makes it possible to vary the depression value that is necessary for the best yarn processing, both in the continuous low-depression dust removal step and in the non-continuous step of capturing the yarn ends at a high-depression.

[0028] For very "dirty" yarn the low-depression dust removal during the winding can be maintained at higher values with respect to those that are sufficient for "clean" yarn. The depression value for dust removal can also be graduated according to the unwinding degree of the spool and according to the winding speed take up, which directly affect the amount of dust developed and that is to be suctioned out from the thread path.

[0029] As far as the non-continuous capturing of the yarn ends at high-depression is concerned, on the other hand, for fluff or very twisted yarns, the high depression for capturing the yarn ends to be joined can be required at values that are higher than those sufficient for normal yarns. Even the interruption of the thread influences the greater or lower difficulty of capturing the yarn ends, especially on the side of the package. For example, if the interruption of the thread is due to a normal high velocity cut, the cut is clean and the yarn end is easier to recover and requires a lower depression suction value. The low velocity cut forms a more frayed tail that is more adherent to the package, when starting up again the cut forms a fluffy tail, the end of the spool forms a tail with less twists: in all these cases the yarn end is more adherent to the package and a greater depression value is necessary to capture it and detach it from the package.

[0030] The control unit 16 of the winding unit 23 is therefore capable of varying the high-depression value to be determined in the suction pipes 9,10 that must capture the yarn ends, by driving the suction device 22 at a predetermined speed rotation rate value, according to the interruption modality of the thread.

[0031] As already shown briefly in figure 1, the dust suction pipe 20 of the dust removal service with continuous low-depression suction is connected, with a duct 30, to the suction unit of the winding units 23, intercepted with an air lock 31, for example an electrovalve, again driven by the control unit 16 of the winding unit and it is normally kept open during the normal winding process. It is kept closed during the joining interventions or, in any case, when the winding is not active, excluding the continuous low-depression dust suction pipe 20.

[0032] As already mentioned, the suction pipes 9 and 10, which capture and move the yarn end on the side of the spool and on the side of the bobbin, respectively, to cooperate with the splicer 6 for the restoration of the thread continuity, operate non-continuously with high depression suction during the interruptions of the normal winding. They are respectively connected with a duct 34 to the suction unit 22 of the winding unit, intercepted with an air lock 35, for example an electrovalve, again driven by the control unit 16 of the winding unit and normally kept closed during the normal winding process, excluding the non-continuous high-depression suction pipes (9,10).

[0033] The air lock 35 is opened during the joining interventions. Basically, the individual suction unit 22 which equips the single winding unit 23 either serves the duct 30 for the low-depression dust removal service or the duct 34 for the high-depression suction. When its winding unit is not active, the suction unit can be switched off.

[0034] Figure 2A, B illustrates the layout of the structure of the single winding unit 23 showing the parallelepiped-shaped bulk and its components of the suction service. In order to clarify the drawing, the components of the suction system according to the invention are shown enlarged.

[0035] The non-continuous suction services, required for the suction pipes 9 and 10, and the continuous suction services are both connected to the suction unit 22 with the duct 34 and with the duct 30, respectively, which are alternatively opened and re-closed. The discharge of the suction device 22 is obtained with a fan outlet 27 that discharges the flow into the atmosphere, downwards and away from the path of the thread. Alternatively, an open header can be foreseen for the discharges of the suction of the winding units.

[0036] On the duct 40 for connecting to the subdivided suction services between the ducts 30 and 34, a wire mesh filter 41 is arranged having the essential function of withholding the "coarse fibers", removed by the high depression by the suction device 22 upstream, when it is connected to the suction pipes 9 and 10 and is activated at high depression. Figure 3 shows an isometric sectioned view of a detail of the filter 41 for "coarse fibers".

[0037] The filter 41 consists of a recipient arranged along the duct 40, in which a wire mesh 43 is arranged for withholding the sunctioned material and in particular the thread waste from the joining of the yarn ends and from the elimination of the defective portions.
The filter 41 is connected with a duct 45, intercepted with a valve 46, to a collective system for cleaning said filters 41, consisting of a small-sized main duct 50 that is arranged along the machine and that receives the flow from the ducts 45 of all the winding units 23. The main duct 50 is served by a high-depression suction device 51, that provides for periodically discharging the material from the filters 41 through pneumatic transport to a centralized filter 53 that is periodically opened and emptied out. According to a preferred embodiment of the invention, the periodic cleaning of the filters 41 is carried out for one filter at a time while its winding unit 23 is operating, or in any case for a small number of units 23 at a time. The operation requires a few seconds and is carried out, firstly by closing the air locks 31 and 35 and by isolating the suction device 22 with the closure of the air lock 57 arranged on the initial portion of the duct 40 - thus avoiding that the cleaning of the filter 41 involves its winding unit 23 in its normal operation - and then by opening the discharge valve 46 of the duct 45 and the air lock 56 of the atmospheric air intake 55 of the filter 41, with the suction device 51 operating. Its suction draws air from the air intake 55 and empties out the filter 41 from the material withheld against the lower part of the wire mesh 43 bringing it to the filter 53 that can be emptied out.

[0038] According to one improved embodiment of the present invention, on the line 40, across the filter 41, a pressure gauge 48 is installed, commonly indicated as "ΔP meter", which is shown in figure 3. The measuring and the knowledge of the degree of saturation or blockage of the wire mesh 43 of the filter 41 makes it possible to carry out the cleaning of the filter no longer after a predetermined time period, but only when the filter reaches a predetermined value of pressure drop. Such a knowledge also makes it possible to compensate for possible pressure drop by graduating both the continuous suction for the dust removal, and the non-continuous suction for capturing the yarn ends.

[0039] A further variant embodiment of the present invention, shown in figures 2C-D in an isometric view and a sectioned view, respectively, foresees the installation of a valve 59 for drawing air from the atmosphere, arranged on the centralized filter 53, to be used during the cleaning cycles of the filters 41. The intake valve 59 is preferably arranged downstream of the filter wall of the filter 53 or in other words, immediately upstream of the suction device 51, which is kept in continuous operation during the cleaning in series of the various filters 41 of the various winding units. The actuation of the suction device 51 brings the main duct 50 and the filter 53 to the depression speed value. Together with the opening of one of the valves 46 for discharging one of the ducts 45, the air intake valve 59 is opened thus discharging the depression of the circuit during the opening stroke of the valve 46. The corresponding increase in the flow rate modifies the working point of the suction device 51 decreasing the depression value. In such a way it is avoided that, at the opening of the air lock 56, the yarn in the filter 41 gets caught during the stroke of the valve 46, which is still opening. Such a possibility would make the seal of the valve 46 problematic, negatively affecting the efficiency and the cost-effectiveness of the suction system according to the invention. With the air intake valve 59 open, the depression is not strong enough to overcome the resistance of the circuit and to suck the yarn from the filter 41 at the opening of the valve 46. When the valve 46 is completely opened, the air intake valve 59 closes back up and the working point of the suction device 51 is immediately restored to the depression value that is necessary to clean the filter 41. Once the yarn withheld by the filter 41 has been evacuated, the valve 46 is closed and the cleaning, of further filters 41 of other winding units, continues.

[0040] The operation of the individual suction system for each of the winding units according to the present invention is illustrated with reference to figures 4A-D.

[0041] Figures 4 are examples of the trends of the suction depressions, of the flow rates and of the powers required by an individual centrifugal suction device serving a winding unit for all the services required. Figure 4A shows, for a centrifugal suction device like the suction device 22, the characteristic trend of the suction depression ΔP in Pascal according to the flow rate in mc/h, parametered on different speed rotation rate values. Figure 4B shows for said centrifugal suction device the characteristic trend of the absorbed power, again according to the flow rate in mc/h, parametered on different speed rotation rate values. Figure 4C, on the other hand, shows the two trends that are characteristic of the depression ΔP required by the winding unit when the high-depression suction valve 35 (curve A) for capturing and handling the yarn ends on the side of the spool and on the side of the package, or the low-depression suction valve 31 (curve B) for the dust removal service are alternatively opened. Such characteristic trends combine with the characteristic curves of the suction device 22 according to figures 4A and 4B. Figure 4D shows the enlarged detail of the trend of the curves A and B for low depression values. The trend of figure 4D shows that the device according to the invention makes it possible, for the dust removal service, to obtain good suction flow rates even with modest depression values, since the suction device 22 is directly connected to the suction pipes 9, 10 or 20 which it must serve, thus avoiding pressure drop of the suction distribution and discard collection network.

[0042] If, for example, in order to find and capture the yarn ends in a winding lot of a predetermined yarn, it is considered necessary for the suction device 22 to have a suction depression ΔP of 6500 Pascal, on the curve A of figure 4C the point A' can be identified corresponding to the flow rate of 270 mc/h and to a rotation around 6600 rpm . For a flow rate of 270 mc/h and a rotation speed of 6600 rpm in figure 4B the power required during the suction with such a depression, that is to say 1.8 kW can be found through extrapolation.

[0043] If, again as an example, after the restoration of the yarn continuity in a winding lot of a predetermined yarn it is considered necessary to require the suction device 22 - for the dust removal service - to have a flow rate of 100 mc/h, on the curve B of figure 4D the point B' corresponding to a suction depression ΔP of only 100 Pascal and to a rotation around 1000 rpm, can be identified. For such a flow rate and such a rotation speed from figure 4B the power required for the dust removal service during the normal winding, that is to say less than 0.07 kW, can be found through extrapolation. If, on the other hand, the suction device 22 is required to have a flow rate of 200 mc/h, on the curve B of figure 4D the point B" corresponding to a suction depression of ΔP of 400 Pascal and to a rotation of around 1650 rpm, can be identified. For such a flow rate and such a rotation speed from figure 4B the power required for the dust removal service during the normal winding, that is to say about 0.25 kW, can be found through extrapolation.

[0044] Compared to suction systems available in winders according to the prior art, the suction system according to the present invention offers substantial advantages.

[0045] With the technical solution according to the present invention long machines are not negatively affected by the non-uniformity of the suction for the various winding units that form it. Energy consumption for the high-depression service at the individual winding units is limited to the duration of the high-depression intervention for the individual suction devices 22. The efficiency of the individual suction devices 22 is not influenced at all by the number of winding units that simultaneously require the service: the machine simply draws a greater amount of energy from the mains for the time it is needed.

[0046] The suction values of the single winding units, according to its operation parameters, can easily be varied according to the contingent requirements of the single unit, or with the flexibility required to simultaneously process many batches of yarn on the same machine.

[0047] With the individual suction devices 22 it is also possible to vary the suction during the capturing of the yarn ends. In more recent winders, the suction pipes 9 and 10 are equipped with sensors for detecting the thread inside them, which make it possible to verify whether the thread on their side has been correctly captured before proceeding to its delivery by moving the suction pipes towards the splicer 6.If the sensors of the yarn ends do not indicate that the yarn end has been taken on one of the two sides, the capturing procedure is repeated on that side for a congruous number of times until it succeeds, by varying the procedure for taking the yarn end. Generally, the greatest capturing difficulties can occur on the side of the package - especially when the yarn end of yarn is sinewy and falls out from the package - and the withholding procedure is varied by the control unit 16 both for the rotation direction and winding speed take up of the package being unwound and the rewinding of the thread, as well as for the suction duration and, in the case of the present invention, also for the suction intensity.

[0048] Such a necessity of special recovery cycles of the yarn end occurs, for example, in the processing of thin or sinewy yarns, in the case in which the thread falls sideways off from the package or in the case of cutting at the restarting of the package. In such cases, after a normal unsuccessful cycle, the procedure is repeated allowing a winding rotation cycle of the package with normal suction. Such a winding rotation cycle makes it possible to configure the untidy windings caused by the previous missed capturing of the yarn end, to recover the yarn end fallen sideways and, in any case, to make the yarn parallel in the central part of the bobbin due to the absence of the traversing motion. At the end of the winding rotation cycle, the normal capturing cycle of the yarn end is thus repeated, unwinding the package again and operating with a depression value that is greater than normal. Such a value can in any case be set according to the trend detected in the single winding unit in the previous cycles.

[0049] According to a preferred embodiment of the invention, during the counter-rotation of the package 12 to unwind the faulty thread from it - which can even take a substantial amount of time in the case of long defects - once the sensors for detecting the thread have indicated that the yarn end has been taken, the high depression suction is no longer necessary and it can be greatly reduced, with a substantial saving of energy. In other words, the suction device 22 is driven at the highest revolution number to provide a higher depression value for capturing the yarn ends of the thread 2 and, once the yarn ends have been captured, driven at a reduced number of revs to provide a lower depression value during the remaining part of the restoration process of the thread continuity.

[0050] The technical solution according to the present invention - apart from the advantages of greater efficiency and simplicity - makes it possible to also have a substantial energy saving for the suction with respect to centralized suction plants according to the prior art.

[0051] The technical solution according to the present invention makes it possible to obtain a substantial improvement of the winding process. It should be noted that in the collecting and capturing phase of the yarn end with high depression suction, the depression value can be adapted:

• according to the type of yarn interruption;
• to carry out special yarn recovery cycles, after a normal unsuccessful cycle;
• depending on the type of yarn, the defects eliminated with cutting, the previous trend of the winding unit.

[0052] It should be noted that during the continuous dust removal phase with low-depression suction, the depression value can be adapted:

• to the unwinding advance degree of the spool;
• to the winding speed take up,
• to the saturation degree of the filter (41).

Claims

1. A winder consisting of a plurality of aligned winding units (23) and served by a suction system which provides the suction required by the single winding units, characterized in that the winding units (23) are each served by an individual rotating suction device (22), driven with a variable rate by the control unit (16) of the winding unit (23), which alternatingly provides continuous low-depression suction, to the suction pipe (20) situated at the spool (1) for dust removal service, excluding the non-continuous high-depression suction pipes (9,10), or non-continuous high-depression suction, to the suction pipes (9,10) for interruption and thread joining interventions (2) and the start of a new spool (1), excluding the continuous low-depression suction pipe (20), for said alternative exclusions opening and closing the communication ducts (30,34) with air locks (31,35) driven by the control unit (16).

2. Winder according to claim 1, characterized in that the rotating suction device (22) consists of a centrifugal impeller (25) activated by an electric motor (26) commanded to operate with a speed rotation rate which varies each time according to the necessity of the winding unit.

3. Winder according to claim 2, characterized in that the motor (26) is a brushless electric motor driven in frequency by the control unit (16) of the winding unit.

4. Winder according to claim 1, characterized in that the individual suction devices (22) are each equipped with a filter (41) for the thread waste, which withholds them upstream of the same suction device, and that said filter is provided with a periodic discharge of the material withheld by pneumatic transport to a centralized filter (53).

5. Winder according to claim 2, characterized in that the centrifugal suction device (22) which equips the individual winding unit (23) is driven at a low number of revolutions to provide the low depression value required during the winding process.

6. Winder according to claim 2, characterized in that the centrifugal suction device (22) which equips the individual winding unit (23) is driven at a high number of revolutions to provide the high depression value required during the restoring process of the thread (2) continuity.

7. Winder according to claim 6, characterized in that the centrifugal suction device (22) which equips the individual winding unit (23) is driven at the highest number of revolution to provide the highest depression value required for capturing the yarn ends of the thread (2) and, once the yarn ends have been captured, driven at a reduced number of revolutions to provide a lower depression value during the remaining part of the restoration process of the thread (2) continuity.

8. Winder according to claim 5, characterized in that the filter (41) is equipped with a pressure gauge (48).

9. Winder according to claim 4, characterized in that the filter (53) is equipped with a valve (59) for drawing air from the atmosphere, preferably arranged immediately upstream of the suction device (51).

10. A winding process with a winder equipped with a plurality of single suction devices (22) which individually equip each winding unit (23) according to one or more of the previous claims, characterized in that in the collecting and capturing phase of the yarn end with high depression suction, the depression value is adapted in relation to the type of thread interruption.

11. A winding process with a winder equipped with a plurality of single suction devices (22) which individually equip each winding unit (23) according to one or more of the previous claims, characterized in that in the collecting and capturing phase of the yarn end with high depression suction, the depression value is adapted for effecting special thread recovery cycles, after a normal unsuccessful cycle.

12. A winding process with a winder equipped with a plurality of single suction devices (22) which individually equip each winding unit (23) according to one or more of the previous claims, characterized in that in the collecting and capturing phase of the yarn end with high depression suction, the depression value is adapted depending on the type of yarn, the defects eliminated with cutting, the previous trend of the winding unit.

13. A winding process with a winder equipped with a plurality of single suction devices (22) which individually equip each winding unit (23) according to one or more of the previous claims, characterized in that during the continuous dust removal phase with low-depression suction, the depression value is adapted to the unwinding advance degree of the spool and to the winding rate.

14. A winding process with a winder equipped with a plurality of single suction devices (22) which individually equip each winding unit (23) according to one or more of the previous claims, characterized in that during the continuous dust removal phase with low-depression suction, the depression value is adapted to the saturation degree of the filter (41).

15. A winding process with a winder equipped with a plurality of single suction devices (22) which individually equip each winding unit (23) according to claim 9, characterized in that, together with the opening of the valves (46) for discharging the filters (41), the air intake valve (59) that discharges the depression of the circuit during the opening stroke of the valve (46), is also opened.

Drawing