"DETECTION DEVICE FOR A SPINDLE OF A SPINNING MACHINE "

[0001] The present invention falls within the field of machinery for the textile industry and ancillary devices for the same. In particular, the present invention relates to a detection device for a ring spinning frame, suitable for detecting the rotational characteristics of the slider that rotates around the spindle of a spinning machine .

[0002] As is known, the spinning machine is one of the most important machines on a spinning line, which starting from a roving, makes it possible to obtain a yarn wound on bobbins .

[0003] The current trend in this specific sector, driven by the need to achieve the best economic performance of the spinning line, is to have spinning machines with a large number of spindles. Currently, there are spinning machines on the market with approximately 2000 spindles.

[0004] It is therefore essential to have devices that can accurately control the operating mode of each spinning station, reliably reporting possible malfunctioning or indications of imminent breakage.

[0005] The reliability of such reports is an important requirement, since the alert must occur if there is a malfunction or if a malfunction is about to occur, but it is equally important for it not to trigger false alerts, for example due to signalling device defects.

[0006] Among the accessory devices used on the spinning machine, the device for detecting the breakage of the yarn being wound during the formation of the bobbin is of particular importance since such breakage is among the most frequent problems during processing, and requires stopping of the spinning station.

[0007] Numerous solutions of devices for detecting the breakage of the yarn being wound during the formation of the bobbin exist. Such solutions reveal the rotation characteristics of the ring; by interpreting these characteristics the integrity or breakage of the yarn can be deduced.

[0008] For example, the solutions described in documents EP 1671119, WO 2013/171774, EP 2772573, CN 203333896, CN 203333895, DE 40 35 385 Al, DE 199 29 467 Al and EP 2 671 984 A2 are known of.

[0009] In addition, the solution described in the document to JP H08 296128 A is known. This solution, however, has some drawbacks, such as false alerts, mainly due to the magnetization of the slider caused by the magnetic field of the detection device.

[0010] The purpose of the present invention is to improve the reliability of a detection device of the aforesaid type, so that it does not emit or emits only rarely false alerts .

[0011] Such purpose is achieved by a detection device according to claim 1 below. The dependent claims describe further embodiment variants of the invention.

[0012] The characteristics and advantages of the detection device according to the present invention will be evident from the description below, made by way of a non-limiting example, according to the appended drawings, wherein:

[0013] - Figure 1 shows schematically a spinning station of a ring spinning machine, provided with a detection device according to the present invention;

[0014] - Figure 2 is a plan view from above of a section of the rail of a spinning machine;

[0015] - figure 3 schematically shows the detection device according to one embodiment of the present invention;

[0016] - figure 4 schematically shows the functioning principle of the detection device according to the present invention;

[0017] - figures 5a and 5b show construction details of an embodiment of a conveyor of the detection device;

[0018] - figure 6 shows an embodiment of the detection device in separate parts;

[0019] - figure 7 schematically shows a control system of the detection devices associated to the spinning machine; [0020] - figure 8 schematically shows the detection device according to a further embodiment of the present invention; and

[0021] - figure 9 schematically shows the positioning of the detection device according to the present invention in spinning machines having different diameters of the spindle ring.

[0022] According to the present invention, a ring spinning machine on a spinning line comprises a plurality of spinning stations 1, aligned along a longitudinal axis X of the spinning machine and typically arranged on two opposite faces for each spinning machine.

[0023] Each spinning station 1 is supplied with a roving 2, generally available in bobbins of roving coming from a roving frame upstream of the spinning machine.

[0024] The spinning station 1 comprises a drawing device 4, comprising a sequence of pairs of pressure-engaged stacked rollers having different peripheral rotation speeds, so to progressively draw the roving passing through the device.

[0025] For example, the spinning station 1 comprises, in the direction of advancement of the roving, a third drawing roller 6a, a second drawing roller 8a and a first drawing roller 10a, which are respectively stacked and pressure-engaged, a third pressure roller 6b, a second pressure roller 8b and a third pressure roller 10b.

[0026] Preferably, the drawing rollers 6a, 8a, 10a are motorised, while the pressure rollers are 6b, 8b, 10b are idle and drawn in rotation since in pressurised contact with the respective drawing rollers.

[0027] The peripheral speed of the drawing rollers increases in the direction of advancement of the roving, so as to perform drawing.

[0028] For example, the peripheral speed of the second roller 8a is greater than the peripheral speed of the first roller 6a and, preferably, the peripheral speed of the first roller 10a is greater than the peripheral speed of the second roller 8a.

[0029] According to one embodiment, downstream of the drawing device or incorporated therein, a device is provided for compacting the roving.

[0030] The spinning station 1 further comprises a fixed guide 12, typically tail-shaped, supported by a first arm 14 connected to a frame of the spinning machine. For example, the fixed guide 12 is made of a rigid wire, usually steel, bent back to form an eyelet 16, crossed by the drawn roving (and possibly compacted) , in order to impose on the roving a preferential path.

[0031] The spinning station further comprises a rotatable spindle 18, having an axis of rotation Z, typically vertical; the spindle 18, supported by a second arm 20 fixed and connected to the frame of the spinning machine, is placed below the fixed guide 12 and generally the axis of rotation Z is coaxial with the eyelet 16.

[0032] A tube 22 is provided on the spindle 18, dragged in rotation by the spindle, so as to wind the yarn Y on itself and form a bobbin.

[0033] In addition, the spinning machine comprises a ring rail 24 translating vertically with reciprocating motion, with prevailing extension along the longitudinal axis X of the spinning machine, and typically common to a plurality of spindles 18.

[0034] The rail 24 has a plurality of apertures 25, longitudinally juxtaposed, each associated with a spindle of a spinning station; the apertures are suitable to be crossed by the spindle and by the bobbin.

[0035] In addition, the spinning station 1 comprises a fixed ring 26, supported by the rail 24, which surrounds the aperture and thus the spindle 18, and a slider 28 perforated, usually in the form of a ring, engaged with the ring 26 and sliding on it so as to rotate around the spindle with a revolving movement.

[0036] The yarn Y passes through the slider 28, so that the yarn is given a desired trajectory.

[0037] For the formation of the bobbin, the spindle 18 is rotated; the yarn Y exiting from the fixed guide 12, passes through the slider 28 and pushes it to rotate around the spindle with a revolving movement; at the same time, the rail 24, which bears the ring 26 and the slider 28 sliding on it, is actuated in reciprocating vertical translation, so as to distribute the yarn along the height of the tube.

[0038] The slider 28 is made of a ferromagnetic material such as steel. According to further embodiments, the slider is made of several parts, at least one of which exhibits ferromagnetic properties. For example, the slider has a core in ferromagnetic material and a nylon coating .

[0039] The spinning station 1 further comprises a detection device 30, typically placed on board the rail 24, suitable to detect the passage of the slider 28 in a detection zone Zr in which the magnetic field is propagated, adjacent to the ring 26.

[0040] The device 30 comprises emission means 30 of a magnetic field, preferably permanent; for example, said emission means comprise a permanent magnet 34, such as a neodymium-iron-boron magnet (Nd-Fe-Bo) .

[0041] According to further embodiments, such emission means comprise an electromagnet.

[0042] The device 30 further comprises a magnetic field sensor 36, for example, a sensor operating by using the Hall effect, preferably linear, and a magnetic flow conveyor 38 suitable to concentrate the magnetic field lines in the detection zone Zr.

[0043] For example, the conveyor 38 is made of a ferromagnetic element, for example steel, preferably of the 100Cr6 (AISI 52100 - ASTM A 29) type.

[0044] The conveyor 38 preferably comprises a tapered portion 40 capable of concentrating the magnetic field lines in said detection zone Zr placed opposite said tapered portion.

[0045] For example, the conveyor 38 is a unit block comprising a cylindrical base 42 and said tapered portion 40, which surmounts the base 42 and has a truncated cone shape .

[0046] For example, according to a preferred embodiment, the conveyor has a total height of 3.2 mm, the base has a diameter of 42 1.6 mm and a height of 1.6 mm, while the tapered portion has the same diameter as the underlying base and ends with a circular surface area with a diameter of 0.8 mm.

[0047] The conveyor 38 is placed opposite a portion of the ring 26, so the tapered portion 40 faces said ring 26, so that the slider 28 sliding on the ring 26 is struck by the field lines L of the detection zone Zr formed by the conveyor .

[0048] According to a further embodiment, the conveyor is made from a box-shaped element 138 (figure 8), for example having a C-shaped cross-section.

[0049] For example, the C-shaped cross-section comprises a pair of end branches 138a, 138b, which preferably extend along an axis M which intersects, for example perpendicularly, the path of the slider 28 on the rail 24.

[0050] Between the free ends of the end branches 138a, 138 the detection zone Zr is formed, crossed by the slider 28 during the revolving motion.

[0051] Preferably, the detection zone Zr in which the magnetic field is propagated and through which the slider 28 transits, is devoid of ferromagnetic components and / or magnetic pole pieces, i.e. devoid of components capable of conducting the magnetic field. In other words, in the detection zone Zr, the magnetic field is propagated only in the air, thus conveniently reducing the magnetic action on the slider (Figure 4) .

[0052] Advantageously, this prevents the slider from being magnetized, avoiding the occurrence of false or inaccurate alerts.

[0053] In general, the magnet 34 is placed on the opposite side to the detection zone Zr from the conveyor 38, for example opposite the base 42 thereof, at a predetermined distance .

[0054] The sensor 36 suitable for detecting a variation of the magnetic field, and in particular a variation of the field between the conveyor 38 and the magnet 34 is placed between the conveyor 38, 138 and the magnet 34

[0055] In addition, preferably, the device 30 comprises a support 50 that supports the magnet 34, the conveyor 38, 138 and the sensor 36; preferably, said support 50 is an electronic board.

[0056] Preferably, in addition, the device 30 comprises a casing 60, suitable to contain the magnet 34, the conveyor 38, 138 and the sensor 36 (and possibly the support 50) and to be connected to the rail 24, so as to position the conveyor 38,18 preferably at least partially protruding from said casing, in the relation to the ring portion 26.

[0057] For example, the casing 60 comprises a lower cover 62, on which the magnet 34, the conveyor 38 and the sensor 36 (and possibly the support 50) are placed, and an upper covering 64, attachable to the lower cover 62, comprising an upper cover 66 having a lumen 68 from which from the tapered portion 40 of the conveyor 38 protrudes, and a covering portion 70 having a main extension along the longitudinal axis X of the spinning machine. [0058] For example, the covering portion 70 is made in a single piece with the upper cover 66 and, preferably, can be coupled to the rail 24, so that, for example, it is outside the rail, but with the upper surface 72 substantially aligned with the upper surface of the rail 24 bearing the rings 26.

[0059] Each detection device 30 is provided for one spinning station 1; having applied a detection device 30 to the respective spinning station 1, the covering portions 70 are longitudinally adjacent to each other, preferably in a continuous, coupled manner, so as to form altogether an upper wall 80 of a raceway 82.

[0060] The raceway 82 can be used, for example, to accommodate the electrical connections for the power supply of the device 30 and/or the transmission of signals from/to the devices 30.

[0061] For each spindle 18 of the spinning station 1 a centreline plane J is defined perpendicular to the longitudinal direction X of the spinning machine and containing the rotation axis Z of said spindle.

[0062] For the detection device 30, a detection plane R is defined passing through the conveyor 38 or the centre of the detection zone Zr, and containing the rotation axis Z of the spindle 18.

[0063] Preferably, the conveyor 38 is placed outside the centreline plane J of the spindle 18; for example, the detection plane R is inclined with respect to the centreline plane J and forms with the centreline plane J an angle K comprised between 15° and 90°, preferably between 15° and 45°, for example equal to 30°.

[0064] This improves operator access to the spindle zone during the design phase and means that the same detection device can be used for spinning machines having different sizes of ring diameter of the spindle.

[0065] For example (figure 9) , for a first spinning machine A, in which the ring has an inner diameter dl and the conveyor is so arranged as to lie on an imaginary circumference of diameter al > dl, the detection device 30 is arranged at a characteristic distance bl from the centreline plane J of the spindle, so that the conveyor is in the desired position such that the slider 28 passes through the detection area of Zr; a second spinning machine B has an inner ring diameter d2 , the conveyor lies on an imaginary circumference of diameter a2 > d2 and a2 > al and the same detection device 30 used for the spinning machine A is placed at a characteristic distance b2 > bl from the centreline plane J of the spindle; lastly, a further spinning machine C has an inner ring diameter d3, the conveyor lies on an imaginary circumference of diameter a3 > d3 and a3 > a2 > al and the same detection device 30 used for the spinning machines A, B is placed at a characteristic distance b3 > b2 > bl from the centreline plane J of the spindle.

[0066] In other words, the detection device 30, and in particular the support 50, is adjustable in position along the longitudinal axis X of the spinning machine and can be fixed to the rail 24, so that the conveyor 38, 138 is correctly placed with respect to the path of the slider 28 during operation.

[0067] During normal operation of the spinning machine, as said, the spindle 18 is rotated; the yarn Y exiting from the fixed guide 12, passes through the slider 28 and pushes it to slide on the ring 26, rotating around the spindle with a revolving movement; at the same time, the rail 24, is actuated in reciprocating vertical translation, so as to distribute the yarn along the height of the tube.

[0068] When the slider 28 passes into the detection zone Zr induced by the conveyor 38, 138, it disturbs the magnetic field existing in said zone, causing a sufficiently substantial variation to be detected by the sensor 36, which emits a respective slider presence signal.

[0069] Appropriately, by processing the signals emitted by the sensor 36, and in particular the slider presence signal, the breakage of the yarn Y (which produces the absence of the slider presence signal), or the rotation speed of the slider (on the basis of the time intervals between one slider presence signal and the next) or further operating irregularities, such as wear of the slider (for example, on the basis of the variation speed of the slider) is detected.

[0070] For the detection of the slider presence signals by each detection device 30 of the spinning machine, a management and control system is provided comprising, for example, a local card 70, for example a microprocessor card, every 16 spindles 18.1-18.16, able to sample the signals from the sensor 34 of the detection device 30.1- 30.16 associated with each spindle, and to perform signal processing .

[0071] In addition, the system comprises a central gateway 72 able to query all the local boards 70, for example able to query the 114 boards of a spinning machine with 1824 spindles (= 114x16) .

[0072] For example, the gateway 72 is operatively connected to the local boards 70 via a wireless connection. The gateway 72 is in turn connected, for example via a serial connection, to a central management unit 74 of the spinning machine, for example a PLC.

[0073] Innovatively, the detection device according to the present invention enables reliable detection to be achieved, thanks to the fact that the conveyor permits a substantial change in the field, detectable by the sensor, even following a slight disorder in the detection zone .

[0074] Advantageously, this permits the use of a permanent magnet to obtain the magnetic field to be monitored.

[0075] According to a further advantageous aspect, the detection device improves operator access to the spindle zone .

[0076] According to yet a further advantageous aspect, during the design of a spinning machine it is possible to use the same detection device for spinning machines having different dimensions of the spindle ring.

[0077] It is clear that a person skilled in the art may make modifications to the detection device described above so as to satisfy contingent requirements while remaining within the sphere of protection of the following claims.