EP1783255A1

EP1783255A1 - Yarn-recovery braking device for weaving lines

Info

Publication number: EP1783255A1
Application number: EP06019216A
Authority: EP
Inventors: Rosario Castelli; Pietro Zenoni
Original assignee: LGL Electronics SpA
Current assignee: LGL Electronics SpA
Priority date: 2005-11-04
Filing date: 2006-09-14
Publication date: 2007-05-09
Also published as: ITTO20050781A1; CN1958901A

Abstract

A yarn-recovery braking device arrangeable along the running path of a yarn upstream of a loom (10) for temporarily recovering a length of yarn (F) from the loom and returning it subsequently. A deviating arm (32) is arranged between two stationary yarn-guide eyelet (28,30) positioned along the running path of the yarn, is pivotally supported about an axis (A) lying at right angles to such path under control of motor means (34), and bears a yarn-guide eyelet (36) positioned along the running path near the axis of rotation and a further eyelet (38) aligned to the second eyelet downstream of it. The arm is operable to rotate from a passive configuration, in which all the eyelets are aligned to one another, to an active configuration in which the arm (32) is rotated of an angle (α) for recovering a length of yarn from the loom, and vice versa.

Description

The present invention relates to a yarn-recovery braking device particularly for weaving lines equipped with air jet looms.
As known, in the weaving processes the loom draws the yarn either directly from a spool or via a weft feeder which draws the yarn from the spool and delivers it to the loom under a controlled tension. The yarn feeder is typically provided with a stop member which stops the yarn unwinding from the feeder in certain stages of the weaving process.
In order to reduce the peaks of tension to which the yarn is subjected when the yarn is stopped by said stop member, it is known to insert a braking device such as that described in US 5,544,680 between the weft feeder and the loom. Such device generally comprises two aligned stationary eyelets through which the yarn is passed, as well as a rotating recovering device which is arranged between the eyelets and bears a pair of pins at diametrically opposed positions with respect to the axis of rotation. At rest, the pins do not interfere with the unwinding yarn. On the contrary, by rotating the recovery device to its operative position, the pins deviate the yarn from its rectilinear path aligned to the eyelets so that a lenght of yarn is stored between the two stationary eyelets. When the recovery member is rotated back to its resting position, the yarn previously recovered is returned to the loom.
The known braking devices of the above-mentioned type have the drawback that, when the yarn is recovered from the loom, the upstream yarn (i.e., the feeder-side yarn) is subjected to considerable peaks of tension. As well known to the person skilled in the art, this circumstance is undesired because it may cause the yarn to break and it may affect the correctness and the accuracy of the feeding process.
Therefore, it is a main object of the present invention to provide a braking device which is capable of recovering yarn from the loom without subjecting the upstream yarn to rises or peaks of tension.
The above object and other advantages, which will better appear below, are achieved by a braking device having the features recited in claim 1, while the dependent claims state other advantageous, though secondary features of the invention.
The invention will be now described in more detail with reference to a preferred, non-exclusive embodiment, shown by way of non-limiting example in the attached drawings, wherein:

Fig. 1 diagrammatically shows the yarn braking device according to the invention positioned between a general weft feeder and an air-jet loom;
Fig. 2 is a perspective view of a braking device according to the invention at rest;
Fig. 3 is a view in side elevation of the device of Fig. 2;
Fig. 4 is a view similar to Fig. 2, which shows the braking device in an operative configuration;
Fig. 5 is a view in side elevation of the braking device of Fig. 4.

With initial reference to Fig. 1, a general air-jet loom 10 draws yarn F from a spool 12 via a yarn feeder 14 that controls the tension of the yarn fed to the loom.
Yarn feeder 14 comprises a stationary drum 16 on which a swivel arm 18 driven by a motor 20 winds a plurality of yarn loops forming a weft reserve RT. A stationary arm 22 projects from motor housing parallel to the axis of the drum and supports an electro-actuated stop member 24 having the aim of locking the yarn F unwinding from drum 16 in certain stages of the weaving process.
A braking device 26 is arranged between yarn feeder 14 and loom 10, which is adapted to reduce the peaks of tension to which the yarn is subjected when the above stop member 24 is energized.
Having now particular reference to Figs. 2-5, braking device 26 according to the invention comprises a first pair of stationary yarn- guide eyelets 28, 30 aligned to each other along the running path of yarn F, and a deviating arm 32 arranged between stationary eyelets 28, 30 which is pivotally supported under control of a motor 34 about an axis A lying at right angles to the running path of yarn F. Arm 32 bears a second pair of yarn- guide eyelets 36, 38 aligned to each other, of which a first eyelet 36 is arranged along the running path of yarn F near the axis of rotation A, and a second eyelet 38 is attached to the free end of arm 32.
As shown in the Figures, both eyelets 28, 30 and 36, 38 have a beveled inner profile. Eyelet 36 is positioned such that the axis of rotation A is tangent to its inner profile on the side of the incoming yarn, and the direction of rotation of the arm is such that yarn F is bent about the axis of rotation A (counter-clock direction in Fig. 5).
Preferably, motor 34 is a brushless motor controlled by position in a conventional way in the field, in order to accurately control the angle of rotation of the arm, the amount of recovered yarn depending from said angle, as will be described below.
In the operation, yarn F to be fed to loom 10 successively passes through the four yarn- guide eyelets 28, 36, 38, 30. At rest, arm 32 is standing in the passive position of Figs. 1-3, with its eyelets 36, 38 aligned to stationary eyelets 28, 30, so that it does not interfere with the running yarn. Before stop member 24 is energized in order to lock the yarn unwinding from the drum, arm 32 is rotated of an angle α to its active position, thereby causing the yarn to be deviated from its rectilinear path aligned to stationary yarn- guide eyelets 28, 30, and a lenght of yarn to be recovered from the downstream loom (Fig. 5). The upstream yarn is not subjected to stress or tensioning because the upstream eyelet 36 on arm 32 is positioned near the axis of rotation A and substantially rotates about itself. As shown in the Figures, the amount of recovered yarn is proportional to the angle of rotation α. In order to return the yarn, arm 32 is rotated back to the initial position, with the four yarn-guide eyelets aligned to one another.
A preferred embodiment of the invention has been described herein, but of course many changes may be made by the person skilled in the art within the scope of the inventive concept. For example, as shown in the Figures, the upstream, stationary yarn-guide eyelet 28 could be not necessary. Furthermore, positioning the inlet eyelet 36 of arm 32 with its inner profile tangent to the axis of rotation A, which allows the device to be operated without disturbing the upstream yarn, should only be intended as a preferred, though non-indispensable, arrangement.

Claims

A yam-recovery braking device arrangeable along the running path of the yarn upstream of a loom (10) for temporarily recovering a lenght of yarn (F) from the loom and returning the yarn subsequently, characterized in that it comprises a deviating arm (32) which is arranged upstream of a first stationary yarn-guide eyelet (30) positioned along the running path of the yarn, is pivotally supported about an axis (A) lying at right angles to the running path of the yarn under control of motor means (34), and bears a second yarn-guide eyelet (36) positioned along the running path of the yarn near said axis of rotation and a third yarn-guide eyelet (38) aligned to the second eyelet and spaced therefrom, said arm being operable to rotate from a passive configuration, in which all said eyelets are aligned to one another, with the second eyelet arranged upstream of the third eyelet along the running path of the yarn, to an active configuration in which the arm (32) is rotated of an angle (α) for recovering a lenght of yarn from the loom, and vice versa.
The braking device of claim 1, characterized in that said deviating arm (32) is positioned between a pair of stationary yarn-guide eyelets (28, 39) aligned to each other.
The braking device of claim 1 or 2, characterized in that said second eyelet (36) is positioned such that the axis of rotation (A) is substantially tangent to its inner profile on the side of the incoming yarn, the direction of rotation of the yarn being such that the yarn (F) is bent about the axis of rotation (A).