Device for flexible retention of a floating system for the advancement of turns of yarn reserve in weft feeders for weaving looms

Abstract: A device (20) for retention of a floating system (13) for the advancement of turns of yarn reserve in weft feeders (10) for weaving looms; comprising a plurality of cylindrical stop elements, each of which comprises a metal coupling pivot (21) and a cylindrical bush (22) made of soft rubber, wherein the bush (22) is provided with at least one perimetric groove (23) which accommodates and retains a continuous ring (24) made of plastics which protrudes radially beyond the cylindrical surface of the bush in order to make contact with the floating system so as to provide rotational retention of the floating system.

Description: The present invention relates to a retention device for the flexible retention of the floating system for the advancement of the reserve turns in weft feeders for weaving looms. Conventional weft feeders are devices provided with a fixed drum whose lateral surface is continuous or divided into laterally adjacent sectors and on which a hollow rotating arm, associated with a driving shaft which is likewise partially hollow, winds a plurality of turns of yarn which constitute a weft reserve. When requested by the loom, at each beat, the turns of the reserve unwind from the drum in order to feed said loom. Sensor means are provided in order to monitor the extent of the weft reserve and to activate the rotating arm in order to replenish the reserve; advancement means are also provided in order to move the turns wound by the arm from the base toward the front output section of the fixed drum. Typically, and according to a known and widely used arrangement, the movement of the turns of the weft reserve on the fixed drum is produced by the composite and substantially undulatory motion of a set of rigid and movable rods which protrude cyclically with respect to the cylindrical surface of the drum, for example protruding from corresponding slots of its lateral surface, or of the sectors of said lateral surface of the drum, and carry the turns on said lateral surface, keeping them spaced by a preset pitch. The movable rods are arranged in groups of four or more rods which are supported at the ends of corresponding spokes which are associated with a central hub. The movable rods, the corresponding supporting spokes and the central hub form a floating system which is freely mounted on the driving shaft of the feeder with the interposition of a bush which can rotate freely on the shaft and whose axis is oblique with respect to the axis of the shaft. Stop means are provided in order to elastically retain the floating system with respect to rotation without however preventing its undulatory motion, applied by said bush and required to produce the advancement of the turns of yarn. In a per se known manner, the rotational retention means are constituted by four cylindrical stop elements made of elastomeric material which are arranged so as to be mutually spaced by 90° with respect to each other at the four dihedral angles formed by the intersection of the spokes of the floating system. Typically, each cylindrical stop element is formed by a threaded metallic coupling pivot on which a cylindrical bush of soft rubber is vulcanized or otherwise rigidly coupled, preferably so that it cannot be removed; by yielding elastically, the bush allows the floating system to perform its undulatory motions freely. The conventional retention means are functionally effective but they suffer the drawback of high wear of the cylindrical stop elements, said wear increasing as the rotation rate of the driving shaft of the weft feeder rises. US-A-5,671,783 discloses a device as claimed in the preamble of claim 1. The aim of the present invention is to eliminate this drawback and within the scope of this general aim an object of the present invention is perfecting the cylindrical stop elements so as to significantly reduce their wear whilst maintaining the elastic flexibility of the retention means as a whole. According to the present invention, this aim, this object and others which will become apparent from the following detailed description are achieved with a device for retention of a floating system for the advancement of turns of yarn reserve in weft feeders for weaving looms, as defined in claim 1. Advantageously, according to the present invention, the continuous ring is made of a polyamide material (nylon) or the like. Further characteristics and advantages of the present invention will become apparent from the following detailed description of a preferred but not exclusive embodiment thereof, illustrated only by way of non-limitative example in the accompanying drawings, wherein: Figure 1 is a partial and partially sectional lateral elevation view of a weft feeder with the retention means according to the present invention; Figure 2 is a front view of the weft feeder, taken in the direction of the arrows II-II of Figure 1; Figure 3 is a partially sectional enlarged-scale view of a cylindrical stop element that composes the retention means according to the present invention. With reference to the above figures, the reference numeral 10 generally designates a conventional weft feeder which comprises a drum with side-by-side sectors 11 on which a hollow rotating arm, associated with a rotating disk 11' arranged at the base of the drum and turned by a driving shaft 12, winds in a conventional way a plurality of turns of yarn which constitute a weft reserve. A floating system, generally designated by the reference numeral 13, is provided in order to move in a conventional way the turns of yarn from the base A toward the front output section B of the drum 11. For this purpose, the floating system 13 is constituted by four sets of rigid and movable rods 15 which protrude cyclically from slots "f" of the drum 11; said sets are connected to a central hub 16 by means of respective supporting spokes 17. In a per se known manner, the central hub 16 is freely mounted on the driving shaft 12 of the feeder 10 with a bush 18 interposed, which can rotate freely on the shaft and its axis is oblique with respect to the axis of said shaft 12. Stop means are provided in order to elastically retain the floating system 13 with respect to rotation without however preventing its undulatory motion, which is applied to it by the bush 18 and is necessary in order to produce the advancement of the turns of yarn on the lateral surface of the drum 11. For this purpose, the stop means comprise cylindrical stop elements 20, preferably four, which are arranged so as to be mutually spaced by 90° and at the four dihedral angles formed by the intersection of the spokes 17 of the floating system 13. According to the present invention and for the stated aim and object, each stop element 20 is structured as shown in detail in Figure 3 and comprises a threaded pivot 21 for coupling to a fixed part 10a of the feeder 10, and a cylindrical bush 22 made of elastomeric material, typically soft rubber, which is vulcanized or otherwise stably retained on a metal flange 21a which is rigidly coupled to the pivot 21. The elastomeric bush 21 is provided with at least one perimetric groove 23 in which a continuous ring 24 of plastic material, typically polyamide material (nylon), is accommodated and retained. As clearly shown in Figure 3, the ring 24 of each stop element 20 protrudes beyond the cylindrical surface of the bush 22 by an extent "t" which has a convenient length, typically between 4 and 8 mm, and in this way the ring makes contact with the spokes 17 of the floating system 13, preventing the rubber of the bush 22 from making said contact and thus avoiding the wear of the bush caused by the relative sliding of the floating system 13 with respect to the stop elements 20. 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 interpretation of each element identified by way of example by such reference signs.

Claims: A device (20) for retention of a floating system (13) for the advancement of turns of yarn reserve in weft feeders (10) for weaving looms, comprising a plurality of cylindrical stop elements (20), each of which comprises a metal coupling pivot (21) and a cylindrical bush (22) made of soft rubber, characterized in that the bush (22) of each cylindrical stop element is provided with at least one perimetric groove (23) which accommodates and retains a continuous ring (24) made of plastics which protrudes radially beyond the cylindrical surface of the bush in order to make contact with said floating system (13) so as to provide rotational retention of said floating system, said cylindrical bush and said ring being subjected to flexural stresses. The device according to claim 1, characterized in that said continuous ring (24) is made of polyamide material. The device according to claim 1, characterized in that said continuous ring protrudes radially, with respect to the cylindrical surface of said bush (22), by 4 to 8 mm.

Inventors: CASTELLI ROSARIO, ZENONI PIETRO, CASTELLI, ROSARIO, ZENONI, PIETRO
Applicants: LGL ELECTRONICS SPA, L.G.L. ELECTRONICS S.P.A.
Application year: 1999
Main classification: B65H51
IPC codes: B65H51, D03D47