SYSTEM OF DETECTION OF SHED CLOSED TO SHUTTLE PASSAGE IN MULTISHED LOOMS

Abstract: System of detection of shed closed to shuttle passage in a multi-step textile loom, constituted by sensitive control bars (15, 16) made elastically movable along the vertical direction, with a stroke at least equalling the vertical shift necessary for the shuttle roller to disengage from the corresponding thrust roller of the chain of dragging of the same shuttle (8, 9), as well as by two sensitive control blades (25, 26) opposite to each other, provided on the divergent side wall, on the rotary-comb facing side, of each shuttle (8, 9), the outward blade (25) of which is fixed and rigid, and the inward blade (26) is longer than the outward one, is rotary around a vertical axis, and by means of a retainer hook thereof keeps in a retracted position a lever pivot (34) urged by a spring to spring outwards relatively to the top shuttle plane (37).

Description: The present invention relates to a multi-phase textile loom incorporating a device for detecting entanglements of warp threads across the shed, and, hence, of shed closed to the passage of the shuttles in a multi-step textile loom, which, by being endowed with characteristics of differential sensitivity, and of memorization of the signalling of the entanglement position, secures an efficacious and optimum operation of the loom, with its immediate stopping only in strictly necessary cases. It is known that the hindrances or obstacles which the shuttle can meet during its run through the shed formed by the warp threads in a multi-step loom are of three types, viz., namely, unstable entanglements of weakly entangled threads, weak but persistent entanglements which are not loosened by the shuttle passage, and strong entanglements. A system of detection of closed shed, for supplying an optimum performance, should hence be able to filter the above said faults, so not to stop the machine in the presence of unstable weak entanglements which are opened by the passage of the same shuttle, to signal the persistent entanglements stopping the loom, and to stop the machine as immediately as possible in the presence of strong entanglements. Furthermore, the system should be also provided with a permanent memory of the signalling of persistent entanglements, for the purpose of anyway securing the looming stoppage even if the instantaneous transmission of the stop signal is hindered by a particular and contingent arrangement of the warp threads. From the prior art, different types of detection systems are already known, but none of these systems are able to fulfill the above-said requirements. DE-B2-2 644 491 discloses a device for exploiting the increase in the resistance to the shuttle running caused by an obstacle present across the shed, such as, e.g., a strong entanglement of warp threads, to cause the same shuttle to be more pressed against a sensitive control bar, which thus interrupts the electrical system of control of the loom and stops this latter. The device now recalled, in addition to being unable of placing an operator in a position to detect the possible weak persistent entanglements, with the consequent production of faulty fabrics, shows the drawback that, due to the natural delay in loom stopping relatively to the entanglement presence signal, the shuttle continues to press against the obstacle present inside the shed, with the possibility that the warp thread mey get broken before the loom is stopped. Another system of the prior art, consisting in providing a side wall of the shuttle with a sensitive control elastic blade controlling the transducers which supply the loom stopping signal, shows, too, the drawback of a delayed action in that, when the blade detects the presence of an obstacle, the shuttle has already penetrated, by a large portion of its length, into the defect, what may cause the fabric under way of formation to be irretrievably damaged. Furthermore, the adjustment of the stiffness of said elastic blade is very complex, in that it is requested to fulfill opposite needs, viz., it should be not too sensitive, so to be able to loosen the unstable entanglements without stopping the loom, and it should be, at the same time, very sensitive, so to be able to signal the persistent entanglements. In practice, an intermediate stiffness is adopted, so that often useless stops of the loom occur, because of the not too low sensitivity of the blade. Finally, none of the known systems is provided with a memory of the stop signal. Purpose of the present invention is precisely that of obviating the above-said drawbacks, and of supplying hence a detection system which may efficaciously and immediately signal the persistent entanglements, immediately stop the loom in the presence of strong entanglements, stop the loom for the least indispensable time and memorize the loom stop signals. That purpose is substantially achieved thanks to the fact that each shuttle is provided with a side profile provided with two different-sensitivity zones. This invention, therefore, provides: A multiphase-weaving-type textile loom comprising a plurality of shuttles, each of which is provided in its bottom portion with a roller, the roller of each shuttle cooperating with a corresponding thrust roller of a dragging chain, and a plurality of control bars that guide said shuttles on their upper portions, said control bars and shuttles being elastically moveable along a vertical direction, characterized in that it further comprises a system for detecting a shed closed by persistent entanglement to the passage of a shuttle, said detection system consisting of: two adjoining control blades, one of which is an inward rotatable blade and the other a shorter rigid and stationary outward blade, both blades located on a divergent side wall of each shuttle on a rotary reed-facing side thereof, wherein said inward control blade is maintained against the outward control blade by a spring; a rotatable lever pin held in a retracted position within each shuttle such that movement of the inward control blade upon engagement of a persistent entanglement frees the rotation of said lever pin, whereupon the lever pin protrudes from the shuttle, thereby pushing a corresponding control bar upwards, and means operatively connected to the loom for converting the upward movement of said control bars into a loom stop signal. More specifically, the divergent side wall on the rotary comb-facing side of the shuttles is equipped with two sensitive control blades opposite to each other, which protrude and diverge beyond the same side wall, from the opposite side relatively to the shuttle point, the outward blade of which, relatively to the rotary comb-facing side, is rigid and stationery, and the inward blade of which is movable around a vertical rotation axis and is kept resting against the said outward blade by a spring, in which position it keeps, by means of a retainer hook it is provided it, in a retracted position inside the thickness of the same shuttle, inside a suitable hollow, a lever pin rotary around a horizontal lever, and urged by a spring to rotate so to protrude from the top shuttle plane, said inward blade being longer than the outward blade. In such a way, in fact, the outward, rigid and stationary blade is efficacious in case of weak and unstable entanglements, in as much as, because of its stiffness, it allows those undesired loom stops to be prevented, which are caused by a few, weakly entangled threads, which are generally disentangled by the passage of the same shuttle, and furthermore extends the operative zone of unstable entanglement disentangling, in that it also adds its length and its divergence to that of the true side wall of the shuttle. The inward blade, which extends lengthwise beyond the outward blade, is, on the contrary, efficacious for the persistent entanglements, in that it allows the loom to be stopped in the presence of entanglements constituted by a few (generally two) warp threads, which are not loosened by the progressing of the shuttle, and of the said outward blade, through the shed. The said stoppage is caused by the persistent entanglement itself, which, in as much as it was not previously loosened by the action of the outward stationary blade, comes to press against the inward, movable, blade which, in its outer portion, protrudes beyond the inward blade, and, by rotating it, releases from its retainer hook the lever pin, which thus springs outwards, by being so urged by its spring, and comes to interact with a sensitive control bar which in its turn closes the excitation circuit of the transducers supplying the loom stop signal. On the other hand, one should keep in his mind that, due to the fact that the lever pin, once sprung, remains protruding out of the shuttle surface, and hence remains in its active position relatively to the sensitive control bars, viz., it memorizes the need for a loom stopping, the loom stopping is anyway secured even if warp threads exist, which prevent an instantaneous transmission of the stop signal. Finally, the strong and resistant entanglements are detected by a whatever shuttle section, starting from its point up to the free end of the said outward, rigid blade, which, when does not find a corresponding opening of the shed, stops the loom in cooperation with the said sensitive control bars which constitute the upper guide elements for the shuttles. Now then, for the purpose of avoiding that, during the necessary time for the loom to stop, the shuttle may continue to act on the obstruction existing across the shed, with the consequent possible breakage of the warp threads, according to another characteristic of the present invention, said sensitive control bars are provided as elastically movable along a vertical direction, with a stroke at least equalling the vertical shift necessary for the shuttle roller to unhook from the corresponding thrust roller of the dragging chain. In such a way, in fact, the increase in resistance to the running of the said shuttle, caused by the obstacle existing across the shed, such as a strong thread entanglement, causes a disengagement, now made possible, of the shuttle, from the corresponding thrust roller of the dragging chain which, by travelling beyond the roller of the same shuttle, causes this latter to be lifted, with the consequent lifting of the related sensitive control bar in the direction opposite to the action of its return springs, and, hence, the closure of the electrical circuit which controls the loom stopping. Summing up, the strong entanglement stops immediately the shuttle and pushes it vertically upwards, together with the overhanging sensitive bar, whilst the dragging chain continues running until the loom stops. The invention is now better explained referring to the hereto attached drawings, which illustrate a preferred form of practical embodiment thereof, supplied for purely exemplifying, and not limitative purposes, in that technical or structural variants can be always supplied without exiting the scope of the present invention. In said drawings: Figure 1 shows a partial perspective, partially sectional view of a multi-step loom adopting the system of closed shed detection according to the present invention: Figure 2 shows a cross-sectional, enlarged-scale view taken along AA path of Figure 1; Figure 3 shows a longitudinal-sectional view, on a different scale, taken along BB path of Figure 2; Figure 4 shows a top view, on an enlarged scale, of a shuttle used on the multi-step loom of Figure 1; Figure 5 shows a partial side sectional view on a different scale, taken according to CC path of Figure 4. Referring to the Figures, with 1 the rotary comb is indicated of a multi-step loom 12, and with 2′ the healds are indicated, which are positioned behind the stationary comb 2, and which, by acting on the warp threads 3 and 3′, generate the different sequential sheds 4, 5, 6, ..., inside which the shuttles 7, 8, 9, ... respectively run, by being dragged into them by the thrust rollers 10, mounted idle on a dragging chain 11 sliding inside a suitable guide provided on loom 12, which cooperate with the rollers 13, which are, in their turn, mounted idle on the same shuttles. The shuttles are furthermore guided on their upper part, inside the sequential sheds, by sensitive control bars 14, 15, 16, ..., which are inserted inside a suitable reverse-"U"-shaped guide 17 integral with the loom 12, are vertically movable, and are elastically pressed onto the same shuttles by being so urged by the springs 18. The structure is such that the bars 14, 15, 16, ... can shift by a vertical stroke at least equal to the vertical shift d (see Figure 5) necessary for the roller 13 of the shuttle to get disengaged from the corresponding thrust roller 10 of the dragging chain 11. At the end of said shift, the bars press pushbuttons 19 which close the circuit of excitation of the transducers 20 which supply the loom stopping signal. In such a way, the presence of a strong entanglement blocks immediately the related shuttle, because this latter can move up and consequently allow the thrust roller to pass; on the other hand, this moving up of the shuttle, and, consequently, of the sensitive bar, causes pushbutton 19 to trip and, hence, it stops the loom. Each shuttle 7, 8, 9, ..., having a substantially triangular pointed shape, with a hollow 21 housing the the warp yarn 23 feeding bobbin 22, is furthermore provided, on its divergent side wall, on the rotary comb-facing side, 24 (see specifically Figure 1), with two sensitive control blades 25 and 26, opposite to each other, which extend and diverge beyond the same side wall, from the opposite side relatively to the point 27 of the same shuttle. The outward blade 25, relatively to the rotary comb 1 facing side, (see specifically Figure 1), is rigid, and is fastened onto said side wall 24 by means of screws 28. The inward blade 26, on the contrary, is movable around the vertical rotation axis 29 (see Figure 4) and is kept resting against the outward blade 25 by being so urged by a spring 30. Said inward blade 26 is furthermore provided with an appendix 31 provided with a retainer hook 32 (see specifically Figure 5), which holds, in a retracted position inside a suitable hollow 33, provided inside the thickness of the shuttle 7, 8, 9, ... (see always Figure 5), a lever pin 34 which, hinged on a horizontal pivot 35, is urged by a spring 36 to rotate so to protrude from the top plane 37 of the same shuttle, as shown in short-dash lines, and indicated by the numeral 34′ in Figure 5, so to come to press against the sensitive control bars 14, 15, 16, ... . Finally, the inward blade 26 is longer than the outward blade 25, so that it protrudes beyond this latter by the length 38 (see Figures 2 and 4), which is the element sensitive to the persistent entanglements. In fact, the presence of a persistent entanglement, i.e., of an entanglement which is opened, but not completely loosened by the passage of the divergent side wall 24 of the shuttle and of its extension constituted by the outward, rigid blade 25, by coming into contact with the said length 38 of the inward blade 26, obliges this latter to rotate to the position as indicated in chain, and by the numeral 26′ in Figure 4, what causes the unhooking of the lever pin 34, which thus comes to protrude to the position 34′ (see Figure 5) and to press onto the corresponding sensitive bar, which stops the loom.

Claims: A multiphase-weaving-type textile loom (12) comprising a plurality of shuttles (7, 8, 9...), each of which is provided in its bottom portion with a roller (13), the roller (13) of each shuttle (7,8,9...) cooperating with a corresponding thrust roller of a dragging chain (11), and a plurality of control bars (14, 15, 16...) that guide said shuttles on their upper portions, said control bars (14, 15, 16...) and shuttles (7,8,9...) being elastically moveable along a vertical direction, characterized in that it further comprises a system for detecting a shed closed by persistent entanglement to the passage of a Shuttle, said detection system consisting of: two adjoining control blades (25, 26), one of which is an inward rotatable blade (26) and the other a shorter rigid and stationary outward blade (25), both blades located on a divergent side wall of each shuttle (7, 8, 9...) on a rotary reed-facing side (24) thereof, wherein said inward control blade (26) is maintained against the outward control blade (25) by a spring (30); a rotatable lever pin (34) held in a retracted position within each shuttle such that movement of the inward control blade (26) upon engagement of a persistent entanglement frees the rotation of said lever pin (34), whereupon the lever pin (34) protrudes from the shuttle (7, 8, 9...), thereby pushing a corresponding control bar (14,15,16...) upwards, and means operatively connected to the loom (12) for converting the upward movement of said control bars (14,15,16...) into a loom stop signal. Multiphase textile loom according to Claim 1, wherein each shuttle (7,8,9...) is triangularly shaped. Multiphase textile loom according to Claim 1, wherein shifting means (18) shifts said shuttle (7,8,9...) and corresponding control bar (14,15, 16...) by at least a vertical stroke necessary for a roller (13) of said shuttle (7,8,9...) to become disengaged from a corresponding thrust roller (13) of a dragging chain (11). Multiphase textile loom according to Claim 1, wherein said means of converting the the upward movement of said control bars (14,15,16...) into a loom stop signal comprises an excitation circuit of a transducer (20). Multiphase textile loom according to Claim 1, wherein said inward control blade (26) has at one end a retainer hook (32) as an appendage (31), the retainer hook (32) controlling the rotation of said lever pin (34). Multiphase textile loom according to Claim 1, wherein said outward rigid control blade (25) engages and frees weak entanglements without causing loom stoppage by movement of said inward control blade (26).

Inventors: BORTOLI, GUILIO, CORRAIN, LUCIANO, MAITAN, GIANNI
Applicants: NUOVOPIGNONE INDUSTRIE MECCANICHE E FONDERIA S.P.A.
Application year: 1987
Main classification: D03D47
IPC codes: D03D51, D03D47, D03D49