EP0340864A1

EP0340864A1 - Process for depositing a reserve of yarn on a winding tube

Info

Publication number: EP0340864A1
Application number: EP89201112A
Authority: EP
Inventors: Donato Castellarin; Sergio Montali; Luigi Colli
Original assignee: Savio SpA; Savio Macchine Tessili SpA
Current assignee: Savio SpA; Savio Macchine Tessili SpA
Priority date: 1988-05-06
Filing date: 1989-05-01
Publication date: 1989-11-08
Also published as: IT8820498A0; IT1218238B

Abstract

The present invention relates to a process for depositing a reserve of yarn of a tube without wound yarn in a rotor-spinning unit during the full bobbin doffing cycle, as well as to a device for carrying out such a process.

The process according to the present invention substantially consists in lifting the pressure roller (2), disengaging it from the extraction roll (4) for the necessary time for forming some reserve windings, and in extracting the yarn (11), by supplying it with the necessary tension for it to exit the spinning unit (8) by means of the revolution supplied to the tube (22) on which, in a region close to one of its ends, the compact, fine string-like reserve of yarn is collected.

Description

The present invention relates to a process for depositing a multi-turn reserve of yarn of a tube without wound yarn in a rotor winding unit during the cycle of full-bobbin doffing.
More particularly, the present invention makes it possible the reserve turns to be given a high enough tension and them to be given, in their geometric arrangement of deposition, that bond cohesion and mutual penetration, which secures a difficultly loosenable and unwindable compactness.
The tension of the yarn plays an important role in the formation of the reserve windings.
A too low tension can originate an unstable fine string-like reserve, which will tend to loosen, originating the so-said "fallen turns" with dangling yarn lengths which, in their turn, cause entanglements of yarns belonging to different bobbins conveyed by a same conveyor belt, or to a same storage.
The yarns dangling from the bobbins furthermore originate undesired deposits around the various members of the belt conveyors, or around similar elements, often hindering, and, in extreme cases, either blocking the same conveyor units. The reserve windings which collapse cause therefore disorders in the conveyances and entanglements of yarns in the storages of the cheeses, of wound yarn units, and cause as well difficulties in the downstream operations when the reserve length is absent, or is broken, or is pulled away (on the creel, the units of wound yarn, i.e., the cheeses, are jointed to each other by using the yarn length obtained from the unwinding of the reserve turns).
A wound yarn unit must be capable of maintaining the reserve turns wound around the tube even after a considerable amount of handling, making it possible the yarn to be quickly unwound in all of the subsequent operations, which contemplate the redrawing of the yarn. Said wound yarn unit can be of any geometrical shapes, and in the present specification, and in the appended claims, it will be simply denominated as "bobbin" or "cheese", with both above terms being used interchangeably.
The causes of an insufficiently high tensioning derive from the difference between the revolution speed of the extraction roll, which reaches nearly instantaneously its steady-state value, and the speed of yarn collection, which has a less steep acceleration slope. Besides that, one should remind that the pressure roller-extraction roll couple is preset at a revolution speed which is related to a helical winding mode, i.e., with a deposition speed which is the sum of the revolution speed and of the translational speed imposed by the yarn-guide element. On the contrary, the speed of deposition of the reserve turns, which are arranged on the tube is a nearly circumferential pattern, is approximately equal to the revolution speed, and is therefore considerably lower than said deposition speed with helical turns.
The use is already known as well of units, or lever systems, which make it possible a yarn reserve to be generated during the step of preparation of the cheese starting end during the doffing cycle, so that the normal work of winding for the production of such wound yarn units, such as bobbins or cheeses, can be subsequently started up.
The disadvantages of these devices, or lever groups, known from the prior art, become evident, in particular, when the yarn reserve is formed, which results to be deposited with not enough tensioned windings, which are therefore easily unwound during the conveyance of the bobbin towards the processing bays and during the downstream manufacturing processes.
Furthermore, not always the processes and the devices known from the prior art are actuated by means of simple methods, i.e., they require complex lever systems, or drive units.
The process and the relevant device for the practicing of the present invention get rid of such drawbacks by means of an original solution, which eliminates any possibilities that not enough tensioned reserve windings may be formed, in that it exploits the tension which is necessary for extracting the yarn from the spinning unit.
A further advantage of the herein disclosed device, as compared to the prior art, is its extreme structural simpleness, from which operating steps endowed with a considerably high reliability derive.
These, and still further advantages are all achieved by means of the process of the present invention for forming a compact reserve gathered as a fine yarn string, on a tube without wound yarn on a rotor spinning unit during the cycle of doffing of a full bobbin, by means of operations activated, after each other, by the elements of a device housed on a slide movable along the front, or the fronts, of the spinning units; and said process is characterized in that:
- the pressure roller is lifted, it being thus disengaged from the extraction roll for the necessary time for some reserve yarn turns to be formed on the tube without wound yarn;
- the yarn is extracted by it being given the necessary tension for it to exit the spinning frame, by means of the revolution supplied to the tube on which, on an area close to one of its ends, some turns are collected, which are necessary for constituting a compact yarn reserve arranged according to a fine string pattern.
The device for practicing the above said process comprises a pressure roller-lifting unit, which is activated for the necessary time for the reserve to be formed, and is associated, as a single body, with a sliding unit.
The device, used for practicing the present invention, is furthermore associated with scheduler means for coordinating the sequence of activation of the various operating elements.
The invention is now disclosed in detail in the following on the basis of the example of practical embodiment schematically depicted in the figures of the hereto attached drawing tables, which summarily illustrate the characteristics of the invention, it being stressed that all the hereto attached drawings, as well as their description, correspond to a preferred form of practical embodiment of the invention, in order to make more understandable the way it is practiced; however, all those structural modifications which fall within the general idea which is exposed in the hereto attached drawings are understood as being comprised within the scope of the requested protection.
In the drawings:

- Figure 1 shows an axonometric perspective view of the device prearranged for forming the yarn reserve deposit wound on the empty tube taken from the tube distributor, and inserted between the cheese-holder arms and shows as well the time point at which the winding of the first reserve turns in the region close to the end of the tube has already been started, while the pressure roller is being kept lifted away from the corresponding extraction roll, and while the tube, driven to rotate by the revolutionary motion of the driving roll, collects the yarn supplying it with the necessary tension for it to be extracted extraction from the winding unit;
- Figure 2 shows a schematic, axonometric perspective view of the device prearranged for forming the reserve yarn deposit wound on the tube inserted between the cheese-holder arms and shows as well the time point at which the deposition of the reserve yarn turns is ended, and the winding of the collection turns has been started up, by means of the transversal movement of the yarn-guide element, and while the pressure roller and the extraction roll, approached to, and pressed against, each other, put the yarn under tension, while extracting it from the spinning frame.

In the figures, same elements are indicated by same reference numerals.
Moreover, for the sake of clearness, in the figures all those parts which are not necessary for the understanding of the invention are omitted, or they are presented in a generic way, in that they are already known from the prior art.
In said hereto attached figures we have that:

1 are the yarn reserve windings deposited according to a fine-string pattern on a region close to the end of the tube 22;
2 is the pressure roller, which is pressed against the motor-driven extraction roll 4 during the bobbin formation step (see Figure 2), or which is moved away from the extraction roll 4 during the step of formation of the tensioned deposit of yarn reserve 1 (see Figure 1);
3 is the outlet opening for the yarn 11 from the rotor spinning unit 8;
5 is the shaft of the extraction rolls 4;
6 is the lever of resetting of the release unit, which intervenes when the preestablished length of wound yarn is reached, and therefore at bobbin end, or when a yarn breakage occurs, or in order to enable or disable the pressure roller-extraction roll couple 2 and 4;
9 is a bracket against which a lifting roller acts, which is provided on the end of an arm driven by an actuator.
The arm and the actuator are kinematic systems borne by the automatic-unit carrier slider, which reciprocates along the machine fronts to perform its patrolling action, and are schematically shown in chain line in 37. When a breakage occurs in yarn 11, or during the doffing cycle, the lifting roll presses against the lower face of the bracket 9 and lifts the pressure roller 2, spacing it way from the extraction roll 4;
10 is an arm lever, suitably shaped, which is capable of retaining and guiding the yarn 11 all through the time which is necessary for some reserve turns to be deposited, and is also capable of lifting the yarn, in order to enable this latter not to interfere with the yarn guide member 24, with this latter performing continuously reciprocating movements 34 by being so driven by the control rod 23. Said arm lever 10 operatively cooperates with the lever 15, obliging the yarn to deposit on an area close to the end of the winding tube 22, according to a well-precise arrangement, and in a well-precise position, both pre-established for the formation of a correct reserve capable of securing that the turns which constitute said reserve are not unwound during the subsequent handling of the bobbin full with wound yarn;
11 is the yarn exiting the spinning unit 8 and is collected, in the direction shown by the arrow 12, on the tube 22;
14 is a blade for shifting the path along which said yarn 11 runs, and said blade can have an either straight, or shaped outline, already known from the prior art:
16 is a case housing the motor devices which control and drive the arms 10 and 15, in order to insert them through the path of the yarn at the beginning of the formation of the reserve yarn turns, and in order to disengage them at the end of the formation of said reserve, leaving the yarn free for being picked by the yarn-guide unit 24;
19 is the arrow which indicates the revolutionary movement of disengagement of the end of the arm 10 from the yarn, at the end of the formation of the reserve yarn turns, deposited in a compact, fine string-like pattern;
18 are the arrows which indicate the pendulum-like movement of transversal oscillation of the arm 15 which guides the yarn to deposit on a limited band, obliging the turns to tie with one another in a precise arrangement which contributes, together with the extraction tensioning, to the formation of a compact fine string-like reserve 1;
20 is the element of reception of the tube 22;
21 is the bobbin-carrier frame;
25 is the friction area, having the shape of an annulus of a limited width, in order that the bobbin which is being formed can be driven by the driver roll 27;
26 and 28 are fixed elements for guiding the yarn 11 which is being collected on the tube 22;
29 is the arrow which indicates the direction of revolution of the extraction roll 4;
30 are the turns of yarn wound on the tube 22 by means of the yarn-guide unit 24;
31 is the arrow which indicates the direction of revolution of the drive roll 27;
32 is the arrow which indicates the direction of revolution induced on the tube 22 by the driving action performed by the driver roll 27 by means of the friction band 25.

The following disclosure of the operating way of the machine made by referring to the hereinabove cited figures refers, first of all, to all those elements which are new, and, therefore, is directed to the device according to the present invention, which carries out a process for depositing a yarn reserve consisting of a plurality of yarn turns on a tube without wound yarn, it being understood that for the device according to the present invention to perform its intended function, complementary devices are known, which are not described in that they are per se already known.
It is known to associate the revolving spinning frame with a slider unit, which essentially performs the functions of bobbin doffing when the pre-established winding length of yarn is reached, of re-fastening the yarn after a yarn breakage, and of cleaning the spinning units.
Said slider unit is made mobile along the spinning front(s) by means of running ways comprising one or more rails, of any shapes, cooperating with suitable rolling means such as wheels, or rollers, or equivalent means.
During the operation of the rotor spinning frame, the slider unit is continuously driven in front of the line of the spinning units, reciprocating in order to perform its patrolling function. Whenever on one of the spinning units 8 the yarn reaches the pre-established length to be collected on the tube 22, said spinning unit stops and emits a signal by means of photo-cells.
The slider unit, when running before the spinning unit, stops as well, and a member provided on the slider unit hooks the bobbin-carrier frame 21, opening the reception elements 20. The bobbin, full of wound yarn, is conveyed to the discharge conveyor belt.
The tube-taking device takes a tube without wound yarn from the tube distributor, and consigns it to the unit which will force the tube on the bobbin-carrier frame 21.
Then, the sequence (known from the prior art) of the operating steps for yarn re-fastening starts. At a predetermined time, presettable by means of digital selectors provided on the control panel, the pressure roller-lifting arm is actuated, and the pressure roller is disengaged from the underlying extraction roll 4.
At the time point following the restoration of the spinning process; the yarn 11 is extracted from the spinning rotor 8, by being supplied with the necessary tension for it to leave the spinning unit by means of the revolutionary motion supplied to the tube 22 by the tube-drive roll 27.
Said yarn 11, driven and dragged in the running direction 12, starts winding around the tube 22, on an area close to an end thereof, according to a geometrical configuration defined by the pre-arranged transversal reciprocating motion 18 of the arm 15, which drives the yarn, clamped by the reception element 20, to form a first wide-turn winding 30 (see Figure 1, upper magnified detail), then driving said yarn to wind up in the opposite direction, forming nearly circumferential turns.
These latter circumferential turns tie the underlying first turn 30 and constitute a compact, fine string-like yarn reserve 1.
At the successive time point, the arm 15, reversing its reciprocating direction, guides the yarn 11 collecting it on the tube 22 as an upper wide turn, which furthermore ties the whole of the underlying reserve turns, while the arm lever 10 rotates, according to the arrow 19, disengaging its end from the yarn 11, in order to leave it free to be engaged by the yarn-guide unit 24 which, during its continuous reciprocating motion, starts forming the bobbin.
All through the necessary time for the reserve turns 1 to be formed, and until the time point at which the yarn is disengaged from the end of the arm lever 10, the pressure roller 2 remains lifted away from the extraction roll 4. This makes it possible the yarn 11 to be extracted from the spinning unit 8 by means of the tension generated by the winding of the same yarn around the tube 22. Therefore, the above process provides a compact, fine string-like reserve of yarn which, therefore, is not prone to be loosened during the following transports and internal handling of the relevant bobbin full of wound yarn.
After that the end of the arm lever 10 is disengaged, the pressure roller 2 is approached to, and pressed against, the extraction roll 4, with the pressure roller-extraction roll couple 2 - 4 being enabled.
In this way, the normal operation is restarted of the spinning unit 8. Tests carried out by the present Applicant demonstrated the perfect repeatibility and the extremely high reliability of the above disclosed process, as developed and disclosed in the present invention, for depositing a compact, fine string-like reserve of yarn, which is difficult to be loosened and unwound.
In fact, the advantage of the herein proposed process, by means of an original solution, is that the deposition of the turns in order to form the reserve of yarn taks place always in the presence of the necessary tension for causing the yarn to exit the spinning unit.
Therefore, no possibilities exist that said reserve turns may be wound according to more or less loose turns.
The hereinabove disclosed form of practical embodiment was reported for merely exemplifying purposes, and is not limitative of the invention. It is clear that many variants, modifications and additions may be supplied by those skilled in the art, without thereby departing from the general concept of the process of the present invention.

Claims

1. Process for depositing a reserve reserve of yarn on a tube without wound yarn on a spinning station, during the cycle of doffing of a full bobbin, wherein said spinning station comprises a spinning rotor and a winding unit with an interposed pressure roller-extraction roll couple, characterized in that:
- the pressure roller of said extraction couple is lifted, it being thus disengaged from the extraction roll for the necessary time for some reserve yarn turns to be formed on the tube without wound yarn;
- the yarn is extracted from the spinning rotor, by being supplied with the necessary tension for it to exit the spinning frame, by means of the revolution supplied to the tube, on which, on an area close to one of its ends, some turns are collected, which are necessary for constituting a compact yarn reserve arranged in a fine string-like configuration.

2. Process according to claim 1, characterized in that the lifting of the pressure roller is carried out by means of a roller-lifting unit, associated, as an enbloc body, with a sliding unit, and actuated for the necessary time for the reserve to be formed.