DEVICE FOR SEEKING A BROKEN YARN END ON A FORMING PACKAGE

Abstract: The invention relates to a device for seeking and withdrawing a broken yarn end on a forming package (7) by means of a number of blowing nozzles (1) located along a line geometrically similar to a helical arc which embraces the package formation cone. The device also allows a yarn portion of determined length to be sucked by a suction cap (3) which tapers upperly into a suction duct (6), the axis of which has a straightened length substantially equal to the length of yarn which needs to be unwound and sucked from the package to enable the subsequent rejoining operation to take place for the automatic reinstatement of the spinning process.

Description: This invention relates to a device for seeking and withdrawing a broken yarn end on a package being formed in order to unwind a yarn length sufficient to allow a rejoining operation to take place for automatically reinstating the spinning process in a continuous ring spinning machine. In textile manufacturing operations for various production purposes it is necessary to seek and release the end of a yarn held fixed in windings which overall form a yarn package. This is necessary in ring spinning machines when the yarn breaks and has to be rejoined to automatically reinstate the spinning process. Automatic carriage apparatus for rejoining broken yarns in ring spinning machines is already known in the art. One of the improvements towards which the present invention tends is in the seeking and withdrawal of a broken yarn end on a package being formed, from which a length is unwound sufficient to complete the rejoining cycle with maximum reliability and speed of implementation, and avoiding any need for unproductive repetition of the operation. In a ring spinning machine for natural or synthetic fibres, during the rejoining of broken yarns it is necessary to bring an actual yarn into contact with a fascicle of textile fibres which has no consistency until the twist of the ring binds the individual fibres together. As the fascicle of textile fibres cannot itself be withdrawn from the feed zone at the exit of the drafting rollers because it would undergo certain breakage, it is absolutely necessary to use the yarn already collected on the package being formed and unwind a part of it to be able to reach the zone for its joining to the fascicle of textile fibres close to the exit of the feed rollers. It is therefore necessary to find the broken yarn end and withdraw it by unwinding a length of it from the package which is at least sufficient to cover the distance between the package and the fascicle of textile fibres fed by the feed rollers. Devices are already known in the art for disengaging and releasing the broken yarn lying on the surface of the package under formation. Said known devices either do not ensure perfect preparation of the yarn under all conditions, or require a considerable use of blown air, or comprise blowing nozzles or sucker elements mounted in a fixed position and therefore unable to be operationally adapted to the variable position of the formation cone on whose surface the broken yarn end to be withdrawn is retained. It is apparent that in this latter case the separation action of the blowing nozzles or sucker elements extends only partly over the surface of the formation cone, or in the limit not at all, with the result that the yarn withdrawal device does not operate effectively. Other devices of the known art include blower and/or sucker elements aided by blades of various materials which rub against the package surface, ie against the wound yarn layers, in an attempt to release the broken yarn end. However the contact pressure of these devices often results in damage to the yarn at several points along the wound surface layers, so creating portions of reduced strength which exert negative influence during the subsequent transformation passages towards the finished product. The aforesaid known devices, especially in the case of yarn which easily felts, have therefore been found unable to sufficiently release the end of a yarn fixed on the package cone. FR-A-2 216 208 discloses a device for seeking and withdrawing a yarn end from a package, having the features of the preamble of claim 1. In the known device the nozzles are arranged concentrically to each other with a component direction in the axial direction of the package, so as to direct the air current onto the external surface of the package and release the yarn end without the need of simultaneously causing the package to be rotated. The released end is then sucked into the suction tube. The location of the nozzles, which act substantially on a same circle, may however not be able to withdraw the yarn under any circumstances. To be sure to reach effective withdrawal it may be necessary to continuously vary the position of the package relative to the nozzles by moving the package up and down. This, on the other hand, may cause uncertainty about the real length of yarn withdrawn and may create problems in the subsequent joining stage, besides complicating the construction of the device. The object of the present invention is to provide a device by which the broken yarn end adhering to the surface of the package formation cone is reliably released and at the same time a yarn portion of sufficient length is unwound to complete the rejoining cycle by which the spinning operation can go to completion. A further object of the invention is to provide a device which when compared to the devices of the known art is constructionally simple and allows the necessary adjustments to be easily made as the geometrical parameters of the package being formed vary and as the type of yarn being wound varies. A device according to the present invention has the features claimed in claim 1. The device may also comprise a control mechanism arranged both to vertically move a package support peg upwards or downwards and to intermittently rotate said support peg to subject the entire surface of the formation cone to the action of the air jets from the blowing nozzles. The control source for rotating the peg and thus the bobbin may provide two rotary movements: firstly a slow rotation for seeking the end of the yarn and extricating it from the wound layers of the formation cone, and then a sufficiently rapid rotation to release into the suction duct the yarn length required for rejoining, this rapidity resulting not only in a reduction in the cycle time but also preventing the yarn fibrillating substantially under the action of the air stream. The pipes of the blowing nozzles may be coupled to respective guide supports fixed to the outer surface of the suction cap, the couplings allowing the pipes both to slide vertically and to rotate angularly to be able to perfectly adjust the operating directions of the air jets blowing against the zone in which the broken yarn end is to be found, on the basis of the dimensions of the package formation cone and the type of yarn wound. According to a further embodiment, the control mechanism located at the base of the package support peg may be able to generate an oscillatory reciprocating motion of limited amplitude straddling the position which the formation cone has assumed, this being done while the package is being rotated about its axis and in the opposite direction to the yarn winding. The invention is described hereinafter on the basis of the embodiment shown diagrammatically on the figures of the accompanying drawings which schematically illustrate the characteristics of the invention. In the accompanying drawings: Figure 1 is a diagrammatic isometric perspective view showing both the device for seeking and withdrawing a broken yarn end and the package under formation, at the moment in which the package formation cone has already been positioned along the helical arc of the blowing nozzles and the yarn end has already been conveyed through the suction duct to the sensing and cutting block; Figure 2 is a cross-sectional view from above, taken on the line A-A of Figure 1, showing a part of the device of the present invention. In the figures identical elements carry the same reference numerals. Again, for reasons of overall clarity, those parts not necessary for understanding the invention are omitted from the figures or are shown only generically as they are of known type. 1 designates the blowing nozzles which are located to surround the formation cone 5 and which operate by blowing jets of air onto the surface of the formation cone 5. Respective position-adjustable pipes 2 of the blowing nozzles 1 are supported by a suction cap 3 under which the upper end of the package 7 is located. Said cap has its lower profile located above the air jets of the nozzles 1 and tapers upperly to engage a suction duct 6 which extends up to a block 4 containing, in a first zone, sensing members for the yarn 8 and, in a second zone, cutting elements 12. This block 4 is the source of an air stream for conveying the end of the yarn 8 through a photo-electric or inductive sensor 9 and into a gap between the cutting blades of the scissor elements 12. On the surface of the package formation cone 5 the broken yarn end is retained. The suction duct 6 is of a length substantially equal to the length of yarn to be unwound and sucked from the package 7, and connects the suction cap 3 to the block 4. The yarn 8 sucked from the package 7 is unwound by a length sufficient to allow the sucked yarn to be sensed by a light barrier 10 arranged in the block 4. The package 7 being formed is held by a peg 11. The scissor elements 12 are so positioned to remove the excess yarn so that the portion of sucked yarn 8 is of a suitable length for rejoining as required for reinstatement of the spinning process. Two optical sensors 14, one emitting and one receiving, are disposed facing each other to form an optical light curtain which when interrupted by the formation cone 5 halts the upward movement of the package 7 being formed to position it correctly under the suction cap 3. A control mechanism block 15 of known type is able to move the support peg 11 for the package 7 vertically upwards and downwards and also able to rotate said peg 11 in the opposite direction to that in which the yarn is being wound so as to disengage and release the broken yarn end reliably and rapidly. Said mechanism 15 is also able to generate, pneumatically or electrically, a reciprocating oscillatory movement of limited amplitude about the position established by the optical sensors 14 to enable the formation cone 5 to be struck by the air jets of the nozzles 1 more effectively. A locking screw 16 for each pipe 2 allows, when slackened, the exact positioning of the blowing nozzle 1 on a guide support 21 by axially and angularly adjusting each nozzle 1 relative to the formation cone 5 such that each air jet strikes the formation cone 5 with high efficiency and in collaboration with the other nozzles. 18 is the direction of rotation of the support peg 11 and thus of the package 7 by the block 15, this direction being advantageously the opposite of that in which the yarn 8 is wound onto the package 7 being formed; 20 is the arrow indicating the vertical raising of the package 7 until its formation cone 5 interrupts the light beam extending between the optical sensors 14. The guide support 21 for the pipes 2 is fixed to the outer surface of the suction cap 3. The following description of operation given with reference to the said figures relates firstly to that which is new and therefore takes into consideration only the device of the present invention which seeks and withdraws the broken yarn end on a package being formed as required for the subsequent rejoining of the yarn to the roving, it being understood that additional devices are required for the other operating stages prior and subsequent to the search for the broken yarn and that these do not form part of the description. It is known to associate a ring spinning machine with a carriage apparatus for automatically rejoining yarns which break during the operation of the spinning spindles. The carriage houses various devices required for the various operational stages involved in rejoining, and therefore also houses the device of the present invention. Said carriage is movable along the spinning machine on runways comprising one or more rails of any shape, cooperating with suitable rolling means such as wheels, rollers or equivalent means. During the operation of the spinning machine, the yarn rejoining carriage is driven to and fro to patrol along the spindles. As it patrols, the carriage apparatus checks by sensor means known in the art whether the yarn is present or not in each spinning spindle. When it detects the lack of one of the yarns the carriage is halted at the spindle where the yarn has been found to be broken and the mechanism for initiating the rejoining procedure is started. This procedure involves stopping the spindle and extracting the package 7 being formed from the spindle line and locating it on the support peg 11 inside the carriage apparatus in a position suitable for seeking and withdrawing the broken yarn end. The peg 11 together with the block 15 of the control mechanism are located in a lower waiting position. When the package 7 has been mounted on the peg 11 the control mechanism 15 is operated to vertically raise the package 7 being formed in the direction of the arrow 20 until its formation cone 5 intercepts and obscures the light beam or optical curtain between the facing sensors 14. When the light beam is intercepted the blowing nozzles 1 are activated and at substantially the same time the control mechanism 15 effects the rotation of the package 7 in the direction of the arrow 18 and suction is applied to the cap 3 and duct 6, this latter being connected to a vacuum pump or similar member, or to any air suction main. The rotation of the package 7 enables its entire frusto-conical surface 5 to be effectively exposed to the air jets leaving the nozzles 1, which by virtue of their overall helical arc arrangement create an air current of ascending vortex type. This latter is channeled along the entire surface of the suction cap 3 at a velocity which increases both because of the effect of the suction zone and because of the effect of the upward taper of the frusto-conical section of the cap 3 which is connected at its top to the suction duct 6. In addition to the rotation of the package 7 the control mechanism 15 generates a reciprocating oscillatory motion of limited amplitude about the position assumed by the package 7 under the suction cap 3 to attain even greater efficiency in disengaging and releasing the broken yarn end. The rotation of the package 7 is advantageously of increasing intensity, ie initially it comprises a few slow rotations necessary to give the blowing nozzles 1 time to disentangle the broken yarn end from the formation cone 5 followed a moment after by a rotation sufficiently rapid to drag along the suction duct the length necessary for passing the yarn 8 through the light barrier 10 and through the scissor elements 12. The presence of the yarn excites the photoelectric barrier 10, which simultaneously deactivates the blowing nozzles 1, the control mechanism 15 and, simultaneously or immediately afterwards, the scissor elements 12. The aforesaid stages could in fact at least partly overlap in time. Immediately following the cutting of the yarn 8 by the scissor elements 12 the package 7 begins to descend by the action of the control mechanism 15. On termination of its descent, the other operational stages follow in accordance with a programmed cycle under the action of various known devices, to complete the automatic rejoining of the yarn withdrawn by the device of the invention to the fascicle of textile fibres leaving the drafting rollers, in order to reinstate the spinning process on the spindle at which the yarn had accidentally broken. The described embodiment has been given by way of non-limiting example only. It is apparent that modifications can be made by experts of the art to the details of the device within the scope of the appended claims.

Claims: A device for seeking and withdrawing a broken yarn end on a package (7) being formed and drawing off by suction a yarn length required to allow a rejoining operation to take place for automatically reinstating the spinning process in a continuous spinning machine, comprising: a series of blowing nozzles (1) located to surround the package cone (5); a suction cap (3) having its lower profile located above the air jets produced by said nozzles (1); a suction duct (6) in fluid communication with said suction cap (3) for receiving a length of yarn (8) unwound and sucked from the package (7) for the subsequent rejoining operation; characterised in that: the nozzles (1) are arranged along a line geometrically similar to a helical arc; a block (4) is connected to the suction cap (3) by the suction duct (6), said block (4) having a first zone for sensing the yarn (8) by means of a sensing light barrier or an electric field (9,10) and a second zone controlled by said first zone and provided with cutting means (12) for cutting the end of the sucked yarn (8) at a position substantially corresponding to the length of yarn (8) required for rejoining; and two facing optical sensors (14) are provided which produce a barrier light beam for sensing the presence of the package cone (5) in order to position said cone (5) along the helical arc of the blowing nozzles (1). A device as claimed in claim 1, characterised in that it further comprises a control mechanism both for vertically moving a package support peg (11) upwards and downwards relative to said suction cap (3) and for intermittently rotating said support peg (11) about the axis thereof to subject the entire surface of the cone (5) to the action of the air jets from the blowing nozzles (1). A device as claimed in claim 1, characterised in that the pipes (2) of the blowing nozzles (1) are axially slidable and angularly rotatable in respective guide supports (21) fixed to the outer surface of the suction cap (3) for adjusting the operating directions of the air jets blowing against the package cone (5) on the basis of the shape and dimensions of the package cone (5) and the type of yarn (8) wound. A device as claimed in claims 1 and 2, characterised in that said support peg (11) is further movable with an oscillatory reciprocating motion of limited amplitude straddling the position which the cone (5) has assumed by the action of the optical sensors (14), while the package (7) is being rotatable about its axis in the direction (arrow 18) opposite to the yarn winding direction.

Inventors: CARATI, FRANCESCO, SARTONI, SANDRO, VERLICCHI, GIOVANNI
Applicants: SAVIO S.P.A.
Application year: 1988
Main classification: D01H15
IPC codes: D01H15, B65H67