PROCESS AND DEVICE FOR COUPLING AND RE-JOINING THE THREAD WITH THE ROVING IN A RING-SPINNING FRAME

Abstract: The present invention relates to a process for automatically coupling and re-joining the thread (7), which may possibly break on a determined spinning bobbin (14) of a ring spinning frame, with the roving (6), or bundle of textile fibres, exiting the last pair of drawing rolls (24,26), as well as to a device for carrying out such a process. The process according to the present invention essentially consists of approaching the end of the thread (7), coming from the spinning bobbin (14), to the bundle of textile fibres (6), exiting the last pair of drawing rolls (24,26), by means of the sucking action performed by a sucking "air race" (2a) inside which said thread and said fibre bundle get coupled and joined with each other, with the spinning process being resumed.

Description: The present invention relates to a process and a device for coupling and re-joining the thread with the roving following thread breakage in a ring spinning frame. The invention is to be used in combination with devices and means known from the prior art, in order to detect the presence of a broken thread, stop the spinning bobbin on which the breakage occurred, carry out the research of the free broken end of the thread on the same spinning bobbin, and catch said free end by means of suitable means. Said roving can be of any compositions or structures, and in the present disclosure and in the appended claims, it will be simply referred to as the "roving" or "textile fibre bundle", with both said terms being used in an interchangeable way. It is known that, owing to various reasons, during the spinning process the thread which is being wound on the spinning bobbins can break once or several times, and, in order to go ahead with the spinning process, the free end of the broken thread has to be found out and re-joined to the textile fibre bundle, or roving, which continues to exit the last pair of drawing rolls of the spinning frame. Said breakage, owing to the same nature of the continuous spinning frames, takes always place along the section running from the outlet from the drawing rolls, and the upper layer of threads wound on the corresponding spinning bobbin. The joining of the broken threads, before saddle-devices for re-joining the broken threads on the continuous ring spinning frames were used, was always done by hand by the operators attending the spinning frames, entrusted with this precise task. The labour costs for the attendance of the continuous spinning frames installed in the spinning factories represented a considerable factor in the computation of the thread production costs. Therefore, completely automatic devices were installed, which, by running along the working fronts of the monitored frames, ascertain whether the thread is present or not, stop when they discover a missing thread, in which case they join the free end of the broken thread with the textile fibre bundle exiting the drawing rolls. After carrying out all the above, they continue their monitoring movement along one or more spinning frames. Said devices have worked to date with satisfactory results, but they resulted to be susceptible of improvement as regards some of their operating units. It also resulted suitable to simplify them from the viewpoint of their executive methodology by resorting to new operating principles, destined to give greater guarantees of reliability and versatility in the application of the device, as a function or the large variety of types of textile materials and of their different manufacturing speeds. Some processes and the devices already known from the prior art for joining the thread with the roving perform said operation in a mechanical way, with a poor reliability being obtained, in that sometimes the joining operation is not successful. In fact, an error can occur in the transversal positioning of the joining device, which does not come into contact with the drawing roll, with the consequence that the textile fibre bundle and the thread are not capable of coupling with each other, owing to the missed contact. The above mentioned error in positioning can also be of longitudinal type, i.e., the joining member can regularly come into contact with the drawing roll, but it may happen that the roving and the thread are not aligned to each other, but are offset relatively to each other. This may happen both owing to an error in positioning of the joining device relatively to the drawing roll, and owing to a right and necessary position of the roving caused by the weft shifter action. Incidentally, the weft shifter action is a reciprocating shifting rightwards and leftwards of the trajectory, of the fibre bundle, in order not to generate a localized wear on the belts and on the rolls of the drawing unit. From Patent Abstracts of Japan, Vol.9, No.324, December 19, 1985, there is known a device for joining a broken thread with a roving in a spinning frame, wherein the roving exiting the drawing rolls is sucked into a suction duct and the broken end of the thread is brought into the same suction duct, in which the thread and roving are entangled and rejoined. In this known device the suction duct is arranged below the drawing rolls in a substantially vertical position, which while favouring entering of the roving into the duct, may create problems for correctly bringing the thread end in the position above the inlet of the suction duct for being correctly sucked therein. Furthermore, since the position of breakage is generally undetermined, different thread lengths may be sucked into the suction duct each time and joints of different characteristics may arise. For bringing a broken thread end into a position for joining there are known rotary pincer elements picking up the thread by suction at their free ends, as disclosed in US-A-3 077 312. From this document it is further known to bring the thread in front of a suction nozzle arranged between a bobbin and the joining unit. This known device is however designed for winding packages from a supply coil or cop, so that in case of breakage, ends of a same thread are joined together. The present invention overcomes the above drawbacks and eliminates any possibilities of missed junction between the thread and the fibre bundle exiting the drawing rolls of a spinning frame, and further provides a device which is structurally simple, from which considerably reliable operating steps arise. This is achieved by a process as claimed in claim 1 and by a device as claimed in claim 2. Preferred embodiments of the device are claimed in claims 3 to 5. The invention is now disclosed in detail on the basis of an example of practical embodiment which is schematically shown in the figures of the hereto attached drawings, and further peculiarities and features will be clarified, it having to be well understood that the invention can be anyway accomplished according to many further structural forms of practical embodiment. In the hereto attached drawings: Figure 1 shows a schematic, axonometric perspective view of a device which carries out the coupling and the re-joining of the thread with the roving, with the presence of the spinning bobbin under way of formation and illustrates as well the time point at which the mobile saddle unit is in its forwards-moved operating position, close to the pair of drawing rolls, in order to enable the suction port of the ejector nozzle to be frontally predisposed in the proximity of the intake port of the fixed sucking nozzle. All this represents the time point preceding the beginning of the operating steps of coupling and rejoining of the thread to the textile fibre bundle. Figure 2 shows a schematic, axonometric perspective view of the device which carries out the coupling and rejoining of the thread with the roving, at the time point at which the free end of the cut thread, and the textile fibre bundle have got coupled with each other, and are being twisted with each other, resuming the spinning process by the relevant spindle. All this represents the time point subsequent to the activation of the ejector nozzle, carried out together with the cutting of the thread, and the resumption of the revolutionary movement of the spindle. In the figures, same elements are indicated by the same reference numerals. Moreover, in the figures, for the sake of clarity of the overall structure, the parts not necessary for the understanding of the invention are omitted, or are presented in a general way, in that they are per se known. Inside a prismatic block 1 an ejector nozzle 2 is provided. On its upper surface, the block 1 is provided with a "V"-shaped, or similarly shaped, groove in order to put and constrain, the taut thread 7 in a diametrical position and frontal adhesion relatively to the inlet port 3 of the ejector nozzle 2. A pipe 4 provides for the primary pressurized fluid, with this latter being injected into a prolonging pipe 11 of the nozzle 2 according to the direction as shown by the arrow 4a. Said pressurized fluid generates the sucking "air race" 2a in the nozzle 2. 5a and 5b are the two positions, the one moved backwards, and the other moved forwards, relatively to the drawing rolls 24 and 26, of a mobile saddle unit 5 supporting the block 1 and the nozzle 2. The position 5a, shown in dashed lines, corresponds to the retracted inoperative position of the mobile saddle unit 5 during the non-splicing-operating step; the position 5b, depicted in solid line, corresponds to the projecting operative position in which the mobile saddle unit 5 is during the splicing operating step. Said positions are obtained by means of known motor means not depicted in that they do not constitute an object of the present invention. 6a is the arrow showing the feed direction of the roving 6. The thread 7 is generated when the textile fibre bundle 6 exiting the drawing rolls 24 and 26 is twisted, and is wound around the underlying spinning bobbin 14 by means of a technology and means which are per se known. A length 8 of the textile fibre bundle 6, approximately equivalent to the length of the individual fibres, gets detached and is removed from the roving 6 owing to the action by a sucking depressure acting in the direction 8a in a fixed sucking nozzle 10. Said textile fibres are continuously conveyed to a waste storage. Scissor elements 9 are arranged on the saddle unit 5 for removing the excess thread immediately before the free end of the same thread gets coupled to the roving. The fixed sucking nozzle 10 is positioned under the pair of drawing rolls 26 and 24, in order to be capable of intaking and removing a textile fibre bundle portion 8 after the breakage of the thread 7, until the re-joining has taken place. A suction pipe 12 is connected to the nozzle 10 and to means destined to generate inside it, and, consequently, inside the nozzle 10, a depressure which is entrusted with the task of collecting from the working area, after the breakage of the thread, the fibres which continue to come out from the rolls 24 and 26, in order to prevent useless and dangerous deposits of wastes from forming along the spinning spindles. The thread is wound on the tube 16 for forming the spinning bobbin 14 with end cone 15. A spinning ring 21 rotating according to arrow 30 causes a true twist to be given to the thread 7 being formed. 20 is the spinning spindle ring provided on the ring rail 22 which is provided with a reciprocating vertical movement, so as to reel the thread 7 according to concentric, mutually overlapping thread layers around the tube 16. The drawing rolls 24 and 26 are positioned at the end side of the per se traditional drawing system. 28 is the arrow which shows the direction of revolution of the spinning spindle, and consequently of the spinning bobbin 14 which is engaged on it. Two plates 18 and 19 frontally opposite to each other, are provided on the saddle unit 5 and urged against each other by elastic elements, or similar elements, so operating substantially in parallel in order to nip the free end of the thread 7. The tension to the thread 7 is supplied owing to the effect of the nipping pressure between said two plates, between which the end portion of the same thread 7 is wedged in, after being picked up from the stationary spinning bobbin 14 after the thread brakage. The following disclosure of the operating way, carried out by referring to the cited figures, is mainly referred to all of the novel elements and, therefore, it only concerns the device according to the present invention, which carries out the coupling and the re-joining of the thread with the roving, it being understood that, in order to operate, it requires complementary devices, which include scheduling means for sequentially operating the elements of the present device. It is known to associate to the ring spinning frame a travelling unit with a saddle device in order to automatically re-join the broken threads during the spinning spindles operation. Said travelling unit is caused to run along the spinning front(s) of the spinning frame, along running ways comprising one or more rail(s), of any shapes, cooperating with suitable rolling means such as wheels, or rollers, or equivalent means. During the operation of the spinning frame, the saddle unit for the re-joining of the threads is continuously frontally reciprocated along the spindle bed, performing a reciprocating patrolling function. During said patrolling monitoring, the travelling device detects, by using detecting means known from the prior art, whether the thread is present or not, on each spinning spindle. When it detects the absence of one of the threads under way of formation, the device stops the saddle unit 5 in front of the splindle wherein the broken thread is, and actuates the re-joining starting mechanisms. At the mean time, and at the time point at which the thread 7 breaks, the textile fibre bundle 6, when exiting the drawing rolls 26 and 24, is shifted and intaken by the sucking nozzle 10 and is held therein until the re-joining begins. By means of an automatic method, the free end of the broken thread is looked for on the upper layers wound on the spinning bobbin 14, and a long enough length of it is unwound. Said thread end is picked up by mobile pincer means, which are provided on the travelling unit and are moved upwards along a pre-established path, in order to insert the thread end between the plates 18 and 19. The thread 7 results hence to be locked, wedged and tensioned along a well defined length, as it clearly results from Figure 1. The above said pincer means are not shown in the drawings, because they are per se known and in practice they could have a whatever shape as suitable for their intended task. During the operating steps of thread search, picking up and transfer, the spindle on which the spinning bobbin 14 under way of formation is slid, is not under operating revolving conditions, and is stopped and kept stationary by suitable means. Before the wedging of the end of the thread 7 between the plates 18 and 19, operations preliminary to the threading of the same thread through the various elements existing between the spinning bobbin 14 and the device of the present invention are carried out, by using known means and operating methods which are per se traditional, and well-known to those skilled in the art. Before the end of the thread 7 is wedged between said plates 18 and 19, the mobile saddle unit 5 is moved towards the area under the drawing rolls 24 and 26 and is stopped in the operative position 5b, as shown in the hereto attached drawings. In said position the inlet port 3 of the ejector nozzle 2 is arranged in front of the inlet port of the sucking nozzle 10, whereas the thread 7 is positioned in a frontal and diametrical position relative to the inlet port 3 of the nozzle 2. The operation of coupling and re-joining of the end of the broken thread 7 with the roving, or textile fibre bundle 6, now starts. The true splicing of the present invention is carried out simply, with the aid of a sucking "air race" 2a, which performs the function of re-joining the textile fibre bundle 6 with the end of the thread 7, amalgamating them with each other, for resuming the spinning process. In order to begin the splicing operation, the arm of the mobile pincers advantageously cooperates. Said arm, in fact, at the end of its movement, which enables the pincers to wedge the end of the thread 7 between the plates 18 and 19, actuates a microswitch, or a similar element, which enables the releasing of the brake which is keeping stopped the spindle of the spinning bobbin 14. This latter starts to revolve, while the scissors 9 are simultaneously, or substantially simultaneously, actuated, and at the same time the ejector nozzle 2 is activated by delivering compressed air into the pipe 4, according to the direction 4a. This latter actuation is such that a suction higher than that in the nozzle 10 is created in the nozzle 2, so as to immediately cause the textile fibre bundle 6 to be intaken and conveyed from the sucking nozzle 10 towards the inlet port 3 and into the interior of the ejector nozzle 2. At the same time, through this latter inlet port 3, the cut end of the thread 7 is captured; said cut end is already subject to a twisting, due to the effect of the already started revolutions, in the direction 30, of the ring 21, which is driven in its turn by the revolutions of the splindle on which the spinning bobbin 14 is slid. At this time, the thread 7 and the roving 6 inside the inlet port 3 of the ejector nozzle 2 approach each other, and interfere and get constrained with each other, in that the fibres of the roving 6 are captured and wrapped by the fibres of the end of the thread 7, with this latter being strongly twisted by the revolutions of the ring 21. In order to prevent the splice from resulting too long, the scissors 9 must be arranged between the plates 18,19 and the inlet port 3 of the ejector nozzle 2 in such a position to cut the thread at a point rather close to the inlet port 3. The scissors 9 are advantageously actuated with a slight delay after the resumption of the revolutions of the ring 21, in order to give the twists the necessary time for them to rise up to the end of the thread nipped between the plates 18 and 19. Incidentally, the above mentioned operating steps can at least partially overlap each other over time. Instead of the scissors 9, which cut the thread 7 with a substantially sharp cut, also the use can be envisaged of a tearing device, of a traditional structure, in order to carry out a gradual breakage of the fibres, in order to improve the appearance of the splice. It should be stressed that the roving 6 does not need to be cut, or torn, in that at the time at which it is intaken into the interior of the ejector nozzle 2, its length is never eccessive. In fact, the roving inside the suction duct 12 does maintain its fibrous structure along an initial length only, which is approximately equal to the length of the fibres. After this length, inasmuch as it does not have any consistency, the roving gets dissolved owing to the effect of the suction. Therefore, for the purposes of the splice, no need exists for the excess of roving length to be removed. At a time point subsequent to the cutting by the scissors 9, suitably timed by an adjustable scheduling apparatus, known from the prior art, the ejector nozzle 2 is disabled, or partially disabled, with the action of the sucking "air race" 2a being discontinued, or limited. In fact, it is of essential importance that the suction by the "air race" 2a does not retain the coupled thread or roving after that the joining is carried out, in order to prevent the thread 7 from remaining stuck, in correspondence of its upper section, to the inlet port 3 of the ejector nozzle 2, being thus hindered in its running towards the spindle, on which it has started to wind on the spinning bobbin 14. In such a way, the continuity of the roving/thread is reliably resumed, thus the continuity of the spinning process being resumed as well. From tests carried out, the perfect repeatibility and the extreme reliability was observed of the joining process according to the present invention, on the whole range of discontinuous-fibre threads. In fact, the main advantage of the herein proposed device is that the free end of the thread 7 meets always the fibres of the roving 6, whichever the position of these latter may be when exiting the drawing rolls 24 and 26. Therefore, the possibilities are nullified, that the thread 7 and the fibres of the roving 6 may not meet each other inside the interior of the sucking "air race" 2a of the ejector nozzle 2, in that both of them are attracted and piloted by suction. It is obvious that the sucking "air race" inside the tube 11, instead of being generated by compressed air delivered through the tube 4, could be obtained by connecting said pipe 11 with a vacuum pump, or with a similar device. The "air race" inside the pipe 11 can be possibly obtained by combining the suction with the blowing of compressed air by means of one or more nozzles. Also the air intake points may be more then one. The inner wall of the nozzle 2 and/or of the pipe 11, besides being of simple conical or cylindrical configuration, may be given a different shape, suitable for giving the fibres and the thread a centrifugal speed, or similar motions. Furthermore, the extensions of the above said pipes can be both rigid and flexible. When the joining action is ended, the mobile saddle unit 5 is returned to its initial position 5a, thus allowing the spinning to be regularly continued, and the reciprocating patrolling by the travelling unit, which is the supporting and moving unit for the saddle unit 5 of the present invention, to be resumed.

Claims: A process for coupling and re-joining the thread with the roving following thread breakage in a ring spinning frame, in which for each spinning spindle a textile fibre bundle (6) comes out of a pair of drawing rolls (24,26), comprising the steps of: shifting the textile fibre bundle (6) from its running direction toward the inlet port of a fixed sucking nozzle (10) and holding the bundle (6) by suction in said sucking nozzle (10); stopping the spinning spindle; bringing the free end of the broken thread (7) from the spinning bobbin (14) in a tensioned state into tangling engagement with the textile fibre bundle (6) to couple and re-join the thread with the bundle (6), and resuming the spinning process; characterised in that: the end portion of the broken thread (7) picked up from the spinning bobbin (14) is first brought into frontal adhesion with, and in diametrical position relatively to, the inlet port (3) of an ejector nozzle (2) while the latter is inactive; the ejector nozzle (2) is activated and a suction higher than that of said sucking nozzle (10) is created in the ejector nozzle (2); the thread (7) is cut or torn in a region close to the inlet port (3) of the ejector nozzle (2) simultaneously with the activation of the suction in the ejector nozzle (2), and the thread (7) and the bundle (6) are sucked into the ejector nozzle (2); the revolutionary movement of the spinning spindle is resumed substantially simultaneously with, or slightly in advance to, the suction of the bundle (6) into the ejector nozzle (2), whereby the thread (7) and the bundle (6) are twisted together. A device for performing the process according to claim 1, comprising: a sucking nozzle (10) arranged below a pair of drawing rolls (24,26) of a spinning unit of a spinning frame for receiving and holding by suction a textile fibre bundle (6) following a thread breakage; means for stopping the spinning spindle and means for bringing the free end of the broken thread (7) from the spinning bobbin (14) into tangling engagement with the textile fibre bundle (6) to couple and re-join the thread (7) with the bundle (6); means for revolving the spinning spindle; characterised in that the device further comprises: a mobile saddle unit (5) supported by a travelling unit movable along the spinning frame; means for detecting the breakage of the thread (7) and stopping the travelling unit with the saddle unit (5) where a broken thread (7) is detected; an ejector nozzle (2) on the saddle unit (5) and means (pipe 4) for creating in said ejector nozzle (2) a suction higher than that in said sucking nozzle (10), said ejector nozzle (2) being positionable proximate to said sucking nozzle (10) for sucking said bundle (6) into said ejector nozzle (2); movable pincer means on said travelling unit for bringing the end of the broken thread (7) into a frontal and diametrical position relative to the inlet port (3) of said ejector nozzle (2); a nipping element (plates 18,19) on said saddle unit (5) for holding said thread end under tension in said frontal and diametrical position; scissors or tearing elements (9) between said nipping element and the inlet port (3) of the ejector nozzle (2) and close to the ejector nozzle (2) for removing an excess thread adjacent said ejector nozzle (2); scheduling means for sequentially operating said breakage detecting means, said spindle stopping means, said pincer means, said nipping element (plates 18, 19), said scissors or tearing elements (9), said suction creating means and said spindle revolving means to operate a twisting of the cut thread (7) with the bundle (6) within said ejector nozzle (2) for re-joining the thread (7) and the bundle (6). A device as claimed in claim 2, characterised in that the saddle unit (5) is movable relative to the drawing rolls (24,26) between a retracted inoperative position (5a) and a projecting operative position (5b) in which said ejector nozzle (2) is arranged with its inlet port (3) in front of the inlet port of said sucking nozzle (10). A device as claimed in claim 2 or 3, characterised in that said ejector nozzle (2) has an inlet pipe (4) for pressurized air spaced from the inlet (3) of the ejector nozzle (2) and directed to create suction at the inlet port (3) of the ejector nozzle (2). A device as claimed in one of claims 2 to 4, characterised in that said saddle unit (5) has a thread guiding prismatic block (1) in which said ejector nozzle (2) is provided, said block (1) having at the top a V-shaped groove for receiving the taut thread (7) in said frontal and diametrical position.

Inventors: SARTONI, SANDRO
Applicants: SAVIO S.P.A.
Application year: 1988
Main classification: D01H15
IPC codes: D01H15