Electropneumatic device for the automatic threading of apparatuses for feeding weft to textile machines and a weft feeding apparatus including said device

Abstract: Electropneumatic device for the automatic threading of apparatuses for feeding weft to textile machines and a weft feeding apparatus including said device, comprising: a first duct (22) and a second duct (23) for feeding pressurized pneumatic fluid, which are cut off by manually-actuated valve means (24) and end respectively in the thread inlet bush (19) and in the thread outlet bush (20) to create a pneumatic flow and a consequent suction current which entrains the thread from one end of the feeder apparatus (10) to the other; an intermediate open channel (28) which is arranged adjacent and parallel to the drum (11) of the apparatus to convey the pneumatic flow and the thread entrained thereby in the free portion comprised between the outlet of the radial arm (13) and a thread braking means (17); a pneumatic pusher (29), which is fed by a third pneumatic duct (32), is arranged at the outlet of the intermediate channel and acts on the braking means (17) to deform it and hinder its elastic action applied to the drum and to guide the thread entrained by the flow through the braking means.

Description: The present invention relates to an electropneumatic device for the automatic and complete threading of apparatuses for feeding weft to textile machines and to a weft feeding apparatus which includes said device. As is known, weft feeders are apparatuses which are suitable to draw the weft thread from spools, to accumulate a reserve of weft in the form of turns of thread wound around a fixed drum and to feed said thread to the textile machine, for example a gripper or bullet loom, with a controlled and constant tension and in an amount linked to the demand of the machine itself. For this purpose, weft feeders comprise, according to a known arrangement, a fixed drum at the base of which a ring is rotatably arranged; said ring is provided with a radial or substantially radial hollow arm in which the thread runs and, by virtue of the rotation of the ring, winds on the drum, forming the turns of the weft reserve. The thread reaches the cavity of the radial arm by passing in a similar cavity of the drive shaft of the disk and unwinds from the drum by passing through a braking means which is in elastic contact with the drum and with a terminal thread guiding ring which is arranged coaxially to said drum; ceramic inlet, intermediate and outlet bushes are provided respectively at the inlet of the drive shaft of the ring, at the outlet of the hollow radial arm and on said terminal thread guide. When the spool located upstream of the pre-feeder ends, or when the thread breaks, the weft reserve is correspondingly depleted and it is necessary to rethread the feeder. Due to the convoluted shape of the path of the thread, and especially to the obstacle constituted by the braking means, the threading operation is performed manually, at least in the front part of the apparatus which is comprised between the intermediate bush and the outlet bush by using a tool, commonly termed "drawboy", which consists of a flexible metallic wire which can follow the path of the thread and at the head of which there is an eye or another means for connecting the thread. In practice, the drawboy is inserted in the pre-feeder, from the front side, through the bush of the thread guide and the braking means, and then the thread is connected to the head of the drawboy; by pulling back the drawboy from the front side, the thread is fully threaded in the pre-feeder; the threading of the rear part of the apparatus, comprised between the inlet bush and the intermediate bush, is performed in a known manner by means of a pressurized pneumatic fluid. The use of the drawboy is quite onerous, requires considerable specialization on the part of the operator but, most of all requires a considerable time for execution, which negatively affects the efficiency of the loom or textile machine. The prior international application WO 89/82944 already described a device which eliminates the use of the drawboy by performing automatic threading in the front part of the apparatus by means of a wall of pressurized fluid, generated by annular nozzles and/or by tubular ducts, which passes through the braking means. The described arrangement assumes, however, that the braking means surrounds the drum so that there is a free annular gap between said braking means and said drum, as in the case of figure 1 of said application, or an annular gap affected by a ring of bristles, as in the case of figure 2 of the same application. However, this known arrangement is unsuitable to produce threading through a continuous braking means which frontally and elastically adheres to the drum of the apparatus, for example a braking means of the kind described in EP-A-0 534 263 in the name of the same Applicants, since such a braking means interacts with the wall of fluid and with the thread entrained by it, preventing its transit. EP-A-0446447 discloses a weft feeder threading device according to the preamble of the appended claims 1 and 12, which also includes a continuous braking means which frontally and elastically adheres to the drum of the apparatus. The aim of the present invention is to eliminate this drawback and, within the scope of this general aim, it has the important object of providing a device which can perform automatically, without any manual intervention, the complete threading of feeders of any kind and in particular of the kind which comprises a continuous braking means which adheres elastically to the drum of the apparatus. Another object of the present invention is to provide an automatic threading device which is structurally simple, highly reliable in operation and suitable to thread any kind of thread. In order to achieve this aim, these objects and others which will become apparent from the following detailed description, the present invention relates to a threading device for weft feeders of the specified type, which comprises: a first duct and a second duct for feeding pressurized pneumatic fluid, said ducts being affected by manually actuated valve means and ending respectively in the rear thread inlet bush and in the front thread outlet bush to create a pneumatic flow and a consequent suction current which entrains said thread from one end of the feeder apparatus to the other; an intermediate open channel, which is arranged adjacent and parallel to the drum of the apparatus to convey the pneumatic flow, and the thread entrained by it, in the free portion comprised between the outlet of the radial arm and the braking means; locating means to align the outlet of the radial arm with the intermediate channel in order to convey the flow and guide the thread entrained by said flow when the threading device is activated; and a pneumatic pusher fed by a third pneumatic duct which is arranged at the outlet of the intermediate channel and acts on a selected portion of the braking means to deform said portion and hinder said portion's elastic action applied to the drum and to guide the thread entrained by the flow through the deformed portion of said braking means. Advantageously, the pusher comprises a concave shaped terminal finger which forms a continuation of the intermediate channel for guiding the thread therethrough. The invention is set out in Claims 1 and 12. Further particular embodiments thereof are set out in Claims 2-11 and 13-14. Further characteristics, purposes and advantages will become apparent from the following detailed description and with reference to the accompanying drawings, given by way of non-limitative example, wherein: figure 1 is a partially sectional elevation view of a weft feeder apparatus with the threading device according to the invention, the threading device being shown in inactive configuration; figure 2 is a partial elevation view, similar to figure 1, illustrating the device in active configuration; figure 3 is an enlarged-scale view of a detail of figure 1; figure 4 is a sectional view, taken along the plane IV-IV of figure 3; figure 5 is an enlarged-scale view of another detail of figure 1; figure 6 is an elevation view, similar to figure 1, of a different type of weft feeder with the device according to the invention. With reference to figures 1 to 5, the reference numeral 10 generally designates a weft feeder apparatus of the type which comprises a fixed drum 11 at the base of which a ring 12 is rotatably arranged; the ring is provided with a hollow radial arm 13 which is connected to a corresponding cavity of the drive shaft 14 of the ring 12. In a per se known manner, the arm 13, by virtue of the rotation of the ring 12, winds the thread F on the drum 11, forming a weft reserve (not shown) in the form of turns of thread which are made to advance toward the head of the drum by an oscillating-plate device 15 which is also per se known. The thread which unwinds from the drum, passing in a thread guide 16 which is coaxial to the drum itself, is subjected to tension caused by the braking means, for example of the type described in the above mentioned prior application in the name of the same Applicant, constituted by a semirigid conical element 17 which is supported and pushed into elastic contact engagement with the drum 11 by an elastic membrane 18 which is in turn supported so that it can be adjusted axially by a rigid arm B which is adjacent to the drum 11; said conical element is tangent to the drum at a section which is adjacent to the one where the circumference is greatest. At the end of the drive shaft 14 there is a ceramic bush 19 for the entry of the thread, and similarly on the thread guide 16 there is a ceramic bush 20 for the exit of the thread. A third intermediate bush 21 is arranged at the outlet of the radial arm 13. According to the present invention, an electropneumatic device D is provided which is suitable to automatically and completely thread the apparatus 10, complete threading being defined as the passage of the thread from the bush 19 to the bush 20 through the intermediate bush 21 and the braking means 17. The device according to the invention comprises a first pneumatic duct 22 and a second pneumatic duct 23 which are cutoff by a monostable valve means 24 and end respectively in the bushes 19 and 20. A duct 25 feeds the pressurized pneumatic fluid, supplied by a source S which is constituted for example by a compressor or by a tank of pressurized fluid, to the valve means 24; a self-releasing button P moves the shutter 26 of the valve means 24 to feed or respectively interrupt the flow of pressurized pneumatic fluid to the ducts 22-23 and to a third duct 32 which will be described hereinafter. The pneumatic fluid fed into the bushes 19-20 creates a flow which is directed from the inlet to the outlet of the apparatus 10 by virtue of the corresponding orientation of the fluid distribution nozzles 27 inside said bushes, and creates a consequent current for the entrainment of the thread F which is directed from the inlet to the outlet of the apparatus 10. In order to convey said flow and the thread entrained by it in the free portion comprised between the bush 21 and the braking means 17, there is an open intermediate channel 28 whose profile is substantially U-shaped; the channel is arranged so that its opening is adjacent and parallel to the drum 11. The channel 28 has an inlet section 28a adjacent to the intermediate bush 21 and an outlet section 28b which is adjacent to the braking means 17 and is inclined along the tangent to the head of the drum 11 which passes substantially through the coupling point of said braking means. At the outlet section 28b, the channel 28 includes a pusher element 29 which is capable of elastically deforming the braking means 17, so as to space it from the drum 11, to hinder its elastic braking action applied to the thread F and allow the passage of said thread entrained by the pneumatic flow. The pusher element 29 comprises a plunger 29a which can slide tight in a pneumatic cylinder 30 defined in the body of the channel 28, with a stem which ends with a concave U-shaped finger 29b which is suitable to engage the edge of the braking means to move it in the specified manner. As clearly shown in figure 1, the U-shaped finger 29b is inclined so that it is substantially parallel to the generatrices of the conical braking means 17, and is chamfered by a radial cut 29c which acts as a deforming inclined plane for the free edge of the braking element. The concavity of the finger 29b is directed toward the drum 11, and said finger constitutes, when the pusher 29 is in active position, an extension of the channel 28 through the braking means 17, in terms both of the conveyance of the pneumatic fluid and of the guiding of the thread. A spring 31 keeps the concave U-shaped finger normally in a position in which it is disengaged from the braking means and the duct 32 feeds pneumatic fluid to the cylinder 30 so as to move the plunger 29a against the action of the spring 31 and deform the braking means 17. In order to establish the pneumatic flow through the channel 28, said channel must be aligned with the bush 21 of the radial arm 13 when the button P of the valve means 24 is pressed to feed the pneumatic fluid to the ducts 22, 23 and 32. For this purpose there is an electromagnetic position-marking element 33 which is energized when a piezoelectric sensor 34, associated with the inlet bush 19, indicates there is no tension in the thread F due either to breakage or to depletion of the thread itself. The element 33 (figure 5) comprises a movable radial pin 35 and a coil 36 which, when energized, moves the pin toward the ring 12. At the end of the pin 35 there is a permanent magnet 37 which has a preset polarity and which, by virtue of the movement of the pin 35, is transferred proximate to, but spaced from, the ring 12 so as to interact with a corresponding permanent magnet 38 of opposite polarity provided on said ring 12. When a piezoelectric sensor 34 indicates lack of tension on the thread, a microprocessor µP associated with the apparatus 10 stops the motor which drives the ring 12 to supply it immediately thereafter with a minimum voltage which corresponds to a minimum speed of the ring 12. Simultaneously, the microprocessor µP energizes the coil 36 which lowers the pin 35. In this manner, when the two magnets 37 and 38 are aligned, the ring 12 stops and remains in the preset position; a proximity sensor 39, which is associated with the magnet 38 and interacts with the magnet 37, cuts power to the motor of the ring 12. The aligned position of the magnets 37 and 38 also corresponds to the alignment between the bush 21 and the channel 28, and therefore, by pressing the button P one produces the pneumatic flow which entrains the thread from the inlet bush 19 to the outlet bush 20 through the bush 21, the channel 28 and the braking means 17, which is loosened by the action of the pusher element 29, which is also activated by the valve means 24. By virtue of this pneumatic flow, the thread F is guided along the path shown in figure 2 and the apparatus is threaded completely. The variation shown in figure 6 differs in that the braking means of the apparatus 10 is constituted by a ring of bristles 170 supported by a ring 171 which surrounds the drum 11; the pusher element 29 acts on a portion of said bristles in a manner similar to what has been described above. More precisely, in the above mentioned figure it can be seen that the U-shaped finger 29b penetrates between the bristles 170 with its convex dorsal part, deforming some of said bristles and spacing them from contact with the drum 11, at the outlet section of the channel 28; the concave U-shaped finger 29b constitutes, when the pusher 29 is in active position, an extension of the channel 28 through the braking element 170 as regards both the conveyance of the flow and the guiding of the thread F. Naturally, without altering the concept of the invention, the details of execution and the embodiments may be altered extensively with respect to what is described and illustrated by way of non-limitative example without thereby abandoning the scope of the invention. Where technical features mentioned in any claim are followed by reference signs, those reference signs have been included for the sole purpose of increasing the intelligibility of the claims and accordingly such reference signs do not have any limiting effect on the scope of each element identified by way of example by such reference signs.

Claims: Electropneumatic device for the automatic threading of weft feeder apparatuses which comprise a fixed drum (11), a hollow rotating radial arm (13), braking means (17) which elastically engage the drum (11), and thread inlet (19) and outlet bushes (20), the device comprising: a first duct (22) and a second duct (23) for feeding pressurized pneumatic fluid, said ducts being affected by manually actuated valve means (24) and ending respectively in the rear thread inlet bush (19) and in the front thread outlet bush (20) to create a pneumatic flow and a consequent suction current which entrains said thread (F) from one end of the feeder apparatus (10) to the other; an intermediate open channel (28), which is arranged adjacent and parallel to the drum (11) of the apparatus to convey the pneumatic flow, and the thread (F) entrained by it, in the free portion comprised between the outlet of the radial arm (13) and the braking means (17); and position-marking means (33) to align the outlet of the radial arm (13) with the intermediate channel (28) in order to convey the flow and guide the thread (F) entrained by said flow when the threading device is activated; the device, further comprising a pneumatic pusher (29) fed by a third pneumatic duct (32), characterized in that said pusher is arranged at the outlet (28b) of the intermediate channel (28) and acts on a selected portion of the braking means (17) to deform said portion and hinder said portion's elastic action applied to the drum (11) and to guide the thread (F) entrained by the flow through the deformed portion of said braking means (17). Device according to claim 1, characterized in that said valve means (24) are of the self-releasing type and in that, in the stable release position, they cut off the pneumatic fluid feed ducts and, in the active actuation position, they feed the pneumatic fluid into said first (22), second (23) and third (32) duct. Device according to claim 1, characterized in that said intermediate channel (28) has a U-shaped profile and is arranged so that its opening is directed toward and adjacent to the drum (11) of the apparatus. Device according to claims 1 and 3, characterized in that said intermediate channel (28) has an inlet section (28b) which is adjacent to the outlet of the radial arm (13) and an outlet section (28b) which is adjacent to the braking means (17), and in that said outlet section (28b) is inclined along the tangent to the drum (11) which passes substantially through the coupling point of said braking means. Device according to claims 1, 3 and 4, characterized in that said intermediate channel (28) includes, at the outlet section (28b) which is adjacent to the braking means (17), the pneumatic pusher (29) which acts on said braking means (17). Device according to claims 1 and 5, characterized in that the pneumatic pusher (29) comprises a plunger (29a) which can slide tight in a pneumatic cylinder (30) defined in the body of the intermediate channel (28) and in that said plunger (29a) is provided with a stem which ends with a concave U-shaped finger (29b) which is suitable to engage the braking means (17) so as to deform them and move them away from contact with the drum (11) of the apparatus, to convey the pneumatic flow and to guide the thread entrained by said flow through said braking means (17). Device according to claim 6, characterized in that said concave U-shaped finger (29b) constitutes, when the pusher (29) is in active position, an extension of said intermediate channel (28) through said braking means (17). Device according to claim 1, characterized in that said locating means (33) are electromagnetic and include a movable pin (35) which is rigidly coupled to the body of the apparatus, is subjected to the field of a movement coil (36) and is provided, at its free end, with a first magnet (37) having a preset polarity which interacts with a second magnet (38) having opposite polarity which is supported by the rotating ring (12) of said apparatus. Device according to claim 8, characterized in that said first (37) and second (38) magnets face each other but are mutually spaced in their active position. Device according to claim 8, characterized in that said first magnet (37) interacts with a proximity sensor (39) arranged adjacent to the second magnet (38) and in that, in the presence of the first magnet (37), said sensor (39) disconnects the power supply of the apparatus. Device according to claim 1 and either one of claims 2 to 10, characterized in that it comprises a piezoelectric sensor (34) which is accommodated in said inlet bush (19), said sensor being sensitive to the tension of the thread (F) and suitable to stop the apparatus in the absence of tension. Weft feeder apparatus for textile machines, comprising: a drum (11) for winding turns of thread which constitute a weft reserve; a rotating hollow radial arm (13) supported by a rotating ring (12), in which the thread wound by said arm (13) on the drum (11) passes; a braking means (17) for the thread, which acts in elastic contact engagement with said drum (11); thread inlet (19) and outlet bushes (20) arranged coaxially to the drum (11); a pair of ducts (22,23), cut off by a monostable valve means (24), for feeding pressurized pneumatic fluid into said bushes (19,20) and create a flow of pneumatic fluid which passes through the apparatus to thread the thread; a channel-shaped intermediate duct (28) with a U-shaped profile, interposed between said rotating radial arm (13) and said braking means (17) and arranged parallel and adjacent to the drum (11) to convey said flow and guide the thread entrained by said flow; the apparatus further comprising a pneumatic pusher element (29) which is fed by a third pneumatic duct (32) controlled by said valve means (24), characterized in that said pusher element (29) acts on a selected portion of the braking means (17) to deform said portion and move the portion away from contact with the drum (11) for the passage of the thread and of the pneumatic flow through the deformed portion of said braking means (17); and in that magnetic locating means (33) are provided to stop the rotating ring (12) and the hollow radial arm (13) in alignment with said intermediate channel (28). Weft feeder apparatus according to claim 12, comprising a braking means which is constituted by a semirigid conical element (17) which is supported and pushed into front elastic contact engagement against the reserve turn winding drum (11) by an elastic membrane (18); said conical element (17) being tangent to the drum (11) at a section of the element which is adjacent to the one with the greatest circumference; characterized in that the outlet section (28b) of said intermediate channel (28) is substantially inclined parallel to the generatrices of the conical element (17), the pneumatic pusher element (29) having a stem with a U-shaped hollow terminal finger (25b) which is also inclined substantially along the generatrices of the conical element (17) and is arranged adjacent to the free ends of said conical element, and in that said U-shaped finger (29b) is chamfered by a radial cut (29c) which acts as an inclined plane suitable to deform the free edge of the conical element (17); said concave U-shaped terminal finger (29b) constituting, when the pusher element (20) is in active position, an extension of the intermediate channel which passes through the braking means (17). Weft feeder apparatus according to claim 12, comprising a braking means which is constituted by a ring of bristles (170) supported by a ring (171) which surrounds the reserve turn winding drum (11), and wherein said bristles (170) elastically engage the surface of the thread winding drum (11), characterized in that the pneumatic pusher element (29) is arranged adjacent to said ring on the side directed toward said intermediate channel (28) and is provided with a stem with a concave U-shaped terminal finger (29b) which engages, with its convex dorsal part, when the pusher (29) is in active position, a corresponding portion of bristles (170), deforming them elastically and spacing them from contact with the drum (11); and in that said concave U-shaped finger (29b) constitutes, when the pusher (29) is in active position, an extension of said intermediate channel (28) which passes through the bristled braking element (170).

Inventors: CASTELLI ROSARIO, PEDRINI GIOVANNI, ZENONI PIETRO, CASTELLI, ROSARIO, PEDRINI, GIOVANNI, ZENONI, PIETRO
Applicants: LGL ELECTRONICS SPA, L.G.L. ELECTRONICS S.P.A.
Application year: 1993
Main classification: D03D47
IPC codes: B65H51, D03D47