Textiles: weaving – Fabric manipulation – Cutter mechanism
Reexamination Certificate
2000-04-06
2001-07-17
Falik, Andy (Department: 3741)
Textiles: weaving
Fabric manipulation
Cutter mechanism
C139S266000, C139S302000
Reexamination Certificate
active
06260586
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a device for cutting the weft yarn in a weaving loom, and in particular in an air weaving loom, of the type suitable for forming weft ends of identical height and hence a fringe on the fabric which is perfectly uniform and aesthetically acceptable, without using a split selvedge.
DESCRIPTION OF THE RELATED ART
It is known that in air looms, both on the side for insertion and on the side for receiving the weft, cutting devices are mounted for performing cutting of the weft yarn, after the weft itself has been inserted into the shed and beaten-up against the fabric being formed. In order to obtain cutting of the various weft yarns inserted in succession into the shed, which is as uniform and homogeneous as possible, and hence obtain a fringe of weft ends of uniform and constant height, it is essential that cutting should be performed with the weft yarn perfectly tensioned.
In order to achieve this condition it is conventionally known in the art to insert an additional group of warp yarns at a certain distance from the last warp yarn of the fabric, thus obtaining the formation of a split selvedge. Special tensioning devices are able to act on the latter and keep the weft ends tensioned up to a zone which is sufficiently distant from the weaving zone and where the conventional cutting devices may be accommodated so as to separate the split selvedge by cutting the weft yarns arranged between the latter and the fabric to the desired uniform length. This weaving technique is able to achieve, as has been seen, a perfectly uniform fringe of weft ends, but it has the drawback that it uses a not insignificant additional amount of yarn for formation of the split selvedge.
More recently, therefore, in the sector of air looms, a technique for the formation of the weft end fringe, which no longer requires the formation of a split selvedge, has been introduced; cutting of the ends is in fact performed on each individual weft after the latter has been beaten-up. Cutting, however, must be preferably performed along the weft insertion line, i.e. along the launching channel formed in the reed of the loom; devices for pneumatically tensioning the weft yarn are, in fact, present along this line, both on the side for insertion and on the side for receiving the weft, said devices being able to keep the weft yarn perfectly stretched during the operation of cutting thereof, so as to ensure that cutting is performed reliably and that the height of the residual weft end is perfectly constant.
The need for the cutting members to be arranged in the immediate vicinity of the weft insertion line involves the consequent need for both the reed and the fabric holder on which the fabric being formed rests to have a longitudinal extension equal to the height of the fabric being processed. In the opposite case, in fact, i.e. when fabrics with a height less than the maximum effective weaving height of the loom are processed on the loom, the cutting devices could not be moved by the desired amount towards the edge of the fabric because they would interfere in fact with the reed and with the fabric holder.
As regards the reed, the problem is solved in a fairly simple manner by replacing on each occasion the reed with one which is of a size suitable for the fabric being processed. Since it is a compact component arranged “outside” the body of the loom, the reed may in fact be replaced rapidly and the only drawback is that associated with the need to stock different types of reeds in the different heights required in the case of the fabric holder, on the other hand, it is not possible to contemplate rapid replacement thereof with another one of suitable dimensions; the fabric holder, is in fact, a component situated inside the loom and in a zone thereof, moreover, where a series of closely arranged additional devices for controlling and regulating weaving is located, and it is therefore inconceivable to envisage replacement thereof in acceptably short time periods, considering also that, during assembly, said fabric holder must be carefully set in position, using spacers for the supports, in order to ensure that it is perfectly leveled.
In the known art it is therefore not possible to perform, hitherto, cutting of the weft yarn along the line for insertion thereof—both on the side for insertion and on the side for receiving the weft—when weaving is performed with a fabric width less than the maximum weaving width of the loom, unless special fabric holders of the telescopic type are used. These consist, as can be easily understood from the term used, of fabric holders formed as several parts—which can slide on one another and can be fixed together—so as to allow adjustment of the overall length of the fabric holder by the desired amount. This type of telescopic fabric holder, in addition to having a higher cost than conventional fabric holders, is also not without drawbacks. In fact, the variation in thickness—albeit small—which necessarily exists between the various fabric holder sections in the zones for mounting on top of one another and joining together two sections of the fabric holder, results in not perfectly uniform weaving. This type of fabric holder can therefore be used only for the production of inferior quality fabrics or for processing with large-size yarns, since in other cases the fabric would not be perfectly uniform, i.e. it would almost always show a weaving mark in the zone joining together two sections of the fabric holder.
SUMMARY OF THE INVENTION
The object of the present invention is therefore that of providing a device for cutting the weft yarn, which allows cutting of the weft yarn to be performed along the line of insertion of the weft, both on the insertion side and on the side-for receiving thereof, irrespective of the length of the fabric holder and the width of the fabric being processed, thus making it possible to dispense entirely with the need for a fabric holder of the telescopic type.
This object is achieved, according to the present invention, by means of a device for cutting the weft yarn in a weaving loom provided with a fabric holder, said cutting device comprising fixed-blade and movable-blade cutting means and motor means for the cutting movement of the movable blade in order to perform cutting of the weft yarn and also at least one guide rail which is transverse with respect to the loom and joined thereto and on which said cutting means are slidable and can be fixed, characterised in that said cutting means comprise a fixed blade group and a movable blade group provided with respective elongated blade-carrying arms on the ends of which said fixed blade and movable blade are mounted, said arms extending respectively above and below said fabric holder of the loom, as far as a cutting zone located beyond the leading edge of the fabric holder itself in the direction of the reed, a zone in which said blades overlap so as to perform cutting of the weft.
REFERENCES:
patent: 2633157 (1953-03-01), Zabriskie et al.
patent: 3779289 (1973-12-01), Bulcock et al.
patent: 5076331 (1991-12-01), Debaes
patent: 5649570 (1997-07-01), Wahhoud et al.
patent: 1 218 502 (1960-05-01), None
patent: 2 634 230 (1990-01-01), None
Falik Andy
Somet Societa' Meccanica Tessile, S.p.A.
Young & Thompson
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