Anti-balloon device for weaving loom weft feeders

Abstract: In a weft feeder (1) comprising a fixed drum (2) on which a rotating arm (3) winds a weft reserve (RT) whose turns unwind from the drum (2), passing through a terminal thread guide (G) under the control of a braking means (4), an anti-balloon device (5) constituted by a frustum-shaped ring (5a) whose smaller diameter is slightly larger than the diameter of the feeder drum (2); the ring is fitted on the drum and is arranged directly ahead of the braking means (4), and the ring (5a) is connected, by way of pivoting means (6) with controlled rotation, to the structure of the feeder (1) so that it can be inclined at an angle to the longitudinal axis of the drum (2) in order to pass from an active position, in which the ring is at right angles to the axis of the drum (2), to a position for threading the feeder (1), in which the ring is inclined at an angle with respect to the drum axis.

Description: The present invention relates to an anti-balloon device for weft feeders of weaving looms of the gripper or bullet type, known as mechanical-insertion looms, and of the jet-insertion type. As it is known, weft feeders for modern weaving looms are devices which comprise a fixed drum, having a constant or variable diameter, on which a weft winding arm, rotating in a fishing-reel fashion around said drum, winds a plurality of turns of thread which constitute a weft reserve. When requested by the loom, at each weft insertion, the turns of the reserve unwind from the drum to be fed to the loom by means of a terminal thread guiding ring, under the control of a braking means which is adapted to keep substantially constant the mechanical tension of the thread that is unwinding. A weft reserve monitoring system, which receives the signals of a sensor adapted to detect the passage of the unwinding turns, moves the rotating arm and restores the weft reserve as its turns unwind to feed the loom. As it is known to those skilled in the art, due to the speed with which the turns of the reserve unwind, the thread, propelled by centrifugal force, arranges itself along the directrices of a solid of revolution being commonly termed "balloon", whose dimensions increase as the speed of the weaving process increases and as the mechanical tension acting on the thread decreases. This solid of revolution or balloon which forms at the drum directly upstream of the braking means causes, as is known, severe drawbacks in the operation of the weft feeder, since it facilitates the formation of tangles of thread, knots or other discontinuities which, when they reach the braking means, generate sudden increases in the mechanical tension on the thread, consequently breaking it and interrupting the weaving process. In order to avoid these drawbacks, it is known to use anti-balloon devices designed to prevent, or at least contain within narrow limits, the formation of said balloon. Typically, anti-balloon devices are constituted by annular elements which surround the drum of the feeder directly upstream of said braking means and lie more or less extensively in the axial direction of said drum, assuming configurations which vary from a simply annular one to a more truly cylindrical one as disclosed in US 4013238, which represents the closest state of the art. In any case, said anti-balloon devices, in order to be effective, are arranged very close to the surface of the drum and therefore significantly hinder the threading - or rethreading, in case of weft breakage - of the feeder, correspondingly delaying the production cycles with economically disadvantageous consequences. The aim of the present invention, starting from the notion of these drawbacks, is to eliminate them, and within the scope of this aim an object of the invention is to provide an anti-balloon device which effectively contrasts the formation of the balloon of thread, in that it maintains its position very close to the surface of the drum, but at the same time does not hinder feeder threading, which on the contrary is highly facilitated, making the device according to the invention very advantageous in modern highspeed weaving processes. According to the present invention, this aim and this and other objects which will become better apparent hereinafter from the following detailed description are achieved with an anti-balloon device for weft feeders having the specific characteristics stated in the appended claims. Substantially, the invention is based on the inventive concept of providing the anti-balloon device in the form of a frustum-shaped ring whose smaller diameter is slightly greater than the diameter of the drum of the feeder, of fitting said ring on the drum, arranging it directly upstream of the braking means, and of connecting said ring, by way of pivoting means with controlled rotation, to the structure of the feeder, so that it can be inclined at an angle to the longitudinal axis of the drum. In this manner, the ring delimits, in the inclined position, a thread passage gap which is significantly larger than the gap between the ring and the drum when the ring is in the active position at right angles to the axis of the drum; moreover, the passage gap is correctly orientated in the direction adapted to facilitate the threading of the weft thread in the terminal thread guiding ring through the directly adjacent braking means. The characteristics, purposes and advantages of the anti-balloon device according to the present invention will become better 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 side elevation view of a weft feeder for mechanical-insertion looms with the anti-balloon device according to the invention; Figure 2 is a partial top plan view of the feeder of Figure 1; Figure 3 is an exploded perspective view of the inner side of the front part of the feeder of Figure 1, illustrating in detail the means for the pivoting of the anti-balloon device to the structure of the feeder; Figure 4 is a perspective view of another detail of said pivoting means. With reference to Figures 1 and 2, 1 generally designates a conventional weft feeder comprising a fixed drum 2 on which a hollow weft winding arm 3, which rotates in a fishing-reel fashion around the drum, winds a plurality of turns of thread which constitute a weft reserve RT. When requested by the loom (not shown) at each weft insertion, the turns of the reserve unwind from the drum 2, passing through a terminal thread guiding ring G, under the control of a braking means 4 adapted to keep substantially constant the mechanical tension of the thread F being unwound. Directly upstream of the braking means 4 there is provided the anti-balloon device, generally designated by the reference numeral 5, having the specified task of preventing the thread, by forming the balloon, from generating tangles, knots and other discontinuities, causing the breakage of said thread in passing through the braking means 4. According to the invention, the anti-balloon device 5 is substantially constituted by a frustum-shaped ring 5a in which the smaller diameter is slightly larger than the diameter of the drum 2 of the feeder. The ring is fitted over the drum and is arranged directly upstream of the braking means 4. The ring 5a is connected to the structure of the feeder 1 by way of pivoting means with controlled rotation, generally designated by the reference numeral 6, so that it can be tilted at an angle to the longitudinal axis of the drum 2 of said feeder. In this manner, the ring 5a delimits, in the inclined position, a passage gap L for the thread (Figure 2) which is significantly larger than the gap between the ring and the drum when said ring is in the operating position at right angles to the axis of the drum; moreover, the gap is correctly orientated in the direction that facilitates the threading of the weft thread F, through the adjacent braking means 4, in the direction of the thread guiding ring G. According to a preferred and advantageous embodiment of the invention, the controlled-rotation pivoting means 6 are provided as shown in the detail views of Figures 3 and 4 and substantially comprise, on the inner side of the cover C of the feeder 1, a tubular hub 61 being rigidly coupled to the cover and provided with a seat 62 which accommodates a cylindrical spacer 63 being in turn provided with a seat 63a for accommodating a disk-shaped permanent magnet 64; the magnet and the spacer are retained in their respective seats by a through screw 65. As clearly shown in Figure 3, the spacer 63 has an uneven edge which is formed by mutually opposite inclined planes which delimit crests CR, adapted to selectively engage, so as to act as position markers, corresponding hollows GO' and GO" provided on a similar spacer 53 (Figure 4) which is rigidly coupled to a coupling bracket 50 of the anti-balloon ring 5a. The spacer 53, in turn, comprises a seat 53a for accommodating a disk-like permanent magnet 54 which is locked by a corresponding screw 55 and whose polarity is opposite with respect to the facing magnet 64. The two mutually opposite magnets 54 and 64 ensure the axial coupling of the spacer 53 to the corresponding spacer 63 but allow limited mutual movements and the mutual rotation of said spacers which moves the ring 5a of the device 5 from the active position, in which said ring is perpendicular to the axis of the drum 2 (Figure 1), to the threading position, in which the ring 5a is inclined by an angle "a" with respect to the axis of said drum (Figure 2); the threading position can be reached by the ring after the disengagement, actuated by a button P, of the braking means 4 and its axial advancement. The two angular positions are rendered stable by the position-marking function of the pivoting means 6; the first position is rendered stable thanks to the engagement of the crests CR of the spacer 63 with the hollows GO' of the spacer 53, and the second position is rendered stable thanks to the engagement of the crests CR with the hollows GO" of the spacer 53. Without altering the concept of the invention, the details of execution and the embodiments may be changed extensively with respect to what is described and illustrated by way of non-limitative example without thereby abandoning the scope of the invention. In particular, according to the invention, it is possible to replace the pivoting means 6 with an electric or pneumatic motor for actuating the rotation of the ring 5a which is controlled by the automatic threading system, if present and activated, in order to incline the ring 5a in step with the threading system. The disclosures in Italian Patent Application No. TO2000A000219 from which this application claims priority are incorporated herein by reference. 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: In a weft feeder (1) of weaving looms, comprising a fixed drum (2) on which a rotating arm (3) winds a weft reserve (RT) whose turns unwind from the drum (2), passing through a terminal thread guide (G) for feeding the loom, under the control of a braking means (4), an anti-balloon device (5), characterized in that said anti-ballooning device is constituted by a frustum-shaped ring (5a) whose smaller diameter is slightly larger than the diameter of the feeder drum (2), said ring being fitted on said drum and being arranged directly upstream of the braking means (4), and in that said ring (5a) is connected, by way of pivoting means (6) with controlled rotation, to the structure of the feeder (1) so that it can be inclined at an angle to the longitudinal axis of the drum (2) in order to pass from an active position, in which said ring is at right angles to the axis of the drum (2), to a position for threading the feeder (1), in which said ring is inclined at an angle with respect to the drum axis. The anti-balloon device according to claim 1, characterized in that said frustum-shaped ring (5a) delimits, in the inclined angular threading position, a gap (L) for the passage of the thread (F) which is significantly larger than the gap between said ring and the drum (2) of the feeder when said ring is in the active position; said gap (L) being further correctly orientated in the direction that facilitates the threading of the weft thread (F) in the terminal thread guiding ring (G) through the directly adjacent braking means (4). The anti-balloon device according to claims 1 and 2, characterized in that said pivoting means (6) with controlled rotation act as position markers for the angular active and inclined positions of said frustum-shaped ring (5a). The anti-balloon device according to the preceding claims, characterized in that said pivoting means (6) with controlled rotation comprise two mutually opposite spacers (53-63) which are rigidly coupled respectively to the ring (5a) of the anti-balloon device (5) and to the structure (C) of the feeder (1), and in that said spacers can rotate one with respect to another and are mutually coupled, so as to allow limited mutual axial movements, by the action of permanent magnets (54-64) which are respectively rigidly coupled to each spacer and have mutually opposite magnetic polarities. The anti-balloon device according to claim 4, characterized in that said permanent magnets (54-64) are disk-shaped. The anti-balloon device according to claim 4, characterized in that said mutually opposite spacers (53-63) are provided with uneven edges which have crests (CR) and hollows (GO'-GO") which mutually and selectively engage in order to render stable said angular active and inclined positions of said frustum-shaped ring (5a). The device according to claims 1 and 2, characterized in that said pivoting means (6) are constituted by a motor which is controlled by an automatic threading system of the feeder (1) and is activated, in order to incline said ring (5a), in step with said threading system.

Inventors: PEDRINI GIOVANNI, ZENOMI PIETRO, PEDRINI, GIOVANNI, ZENOMI, PIETRO
Applicants: LGL ELECTRONICS SPA, L.G.L. ELECTRONICS S.P.A.
Application year: 2001
Main classification: D03D47
IPC codes: D03D47, B65H57, B65H51