Textiles: weaving – Weft manipulation – Weaving with stationary weft supply
Reexamination Certificate
2000-05-08
2001-10-30
Falik, Andy (Department: 3741)
Textiles: weaving
Weft manipulation
Weaving with stationary weft supply
Reexamination Certificate
active
06308743
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a device for passing weft yarns to at least one weft insertion means on a weaving machine, which can be operated in order either to bring a weft within the weft feed area of the weft insertion means so that a weft can be inserted, or to hold it out of this feed area to effectuate a weft cancellation.
This device also relates to a weaving machine provided with such a offering device for wefts.
Known weaving machines comprise a mechanism for inserting wefts between warp yarns. Such a mechanism comprises one or more weft insertion means, such as for example rapiers, which can be operated in order in the course of successive weft insertion cycles to bring a respective weft into a shed formed between warp yarns.
In order to be able to weave certain weave constructions or to be able to weave in an efficient manner it is necessary to prevent the insertion of one of more wefts in the course of certain insertion cycles. By means of the above described device this can be effected automatically. The prevention of the insertion of a weft by a weft insertion means is generally referred to by the term “weft cancellation”.
Such offering devices for wefts with which weft cancellations can be effected automatically are generally known.
The known devices comprise weft cutters which are provided in order after each weft insertion to cut off the piece of weft yarn, inserted in the fabric, from the weft yarn fed from the supply package, and in order, after cutting off the piece of weft, to clamp the free extremity of the fed weft. These weft cutters are connected to the weaving batten and therefore move back and forth with every beating-up. The clamped weft is brought below the movement path of a rapier in the course of the return movement of the weaving batten. These devices furthermore also comprise a swivelling arm with a guiding eye for the weft. The swivelling arm is rotatably connected to the frame of the weaving machine and can be operated in order whether or not to bring the weft extending through the guiding eye above the movement path of the rapier.
If a weft has to be inserted the weft cutters are operated in order to cut through and clamp the weft. The clamping means move with the weaving batten and bring the weft under the rapier movement path. The swivelling arm is at that moment rotated to a position in which the guiding eye brings the weft above the movement path of the rapier, so that the part of the weft extending between the clamping means and the guiding eye is within the feed area of the rapier.
If on the other hand a weft cancellation has to be effected the weft cutters are not operated in order to cut through the weft. The weft therefore remains connected to the fell of the fabric and is also not clamped by the clamping means. Because of this the weft is also not carried to below the rapier movement path, with the beating-up movement of the batten. The swivelling arm is also not operated to bring the weft to above this movement path, so that the weft remains outside the feed area of the rapier.
A disadvantage of these known devices is that the swivelling levers and their operation are rather complex and expensive.
SUMMARY OF THE INVENTION
The purpose of this invention is to provide such a device which on the one hand is simpler and cheaper than the known devices, and which on the other hand can nevertheless operate in a very efficient manner and enables a proper and fast operation of the weaving machine, without any reduction of quality for the fabrics.
This objective is achieved by providing a device with the characteristics mentioned in the first paragraph of this specification, which furthermore comprises a yarn carrier which is provided in order to be moved by a weaving machine drive in order to bring a weft within the aforesaid feed area, and which can be operated in order to bring the weft and the carrier into a first and a second mutual position, while the weft in the first mutual position can, and in the second mutual position cannot be carried along by the yarn carrier to the aforesaid feed area.
The movement of the yarn carrier can among others be effected by the weaving batten drive, whereby the yarn carrier is for example attached to a part of the weaving machine moving synchronously with the movements of the weaving batten. The offering of a weft to a weft insertion means therefore no longer requires a separately operable drive mechanism. The expensive and complex swivelling levers are therefore no longer necessary. The performance of a weft cancellation can occur by so altering the mutual position of the weft and the yarn carrier that this weft cannot be carried along by the yarn carrier. This can be effected in a very efficient manner with simple means.
With a weft cancellation the piece of weft that was inserted in the course of the previous insertion cycle is not cut off from the weft supply means, so that this remains connected to the fabric. The weft is not clamped by the moving weft cutters during the beating-up movement and is with use of the device according to this invention furthermore also not carried along by the yarn carrier, so that there is no danger at all that the weft is withdrawn from the fell of the fabric.
This danger would namely exist if the known swivelling levers with guiding eye were just to be replaced by a guiding eye that is permanently attached to the weaving batten. Indeed with a weft cancellation the non-cut-off weft yarn extending through the guiding eye would in the course of the return movement of the weaving batten, as a result of the frictions in the guiding eye, be withdrawn from the fell of the fabric. The quality of the fabric would be reduced because of this. More specifically faults would be discovered in the pile height.
Especially with fast-running weaving machines these frictions would also lead to a non-cut-off weft no longer being able to be held sufficiently under tension. With an offering following thereafter of this weft to a weft insertion means, the chance would be inadmissibly great that the weft is not properly stretched, and consequently is not carried along by the weft insertion means. The quality of the fabric would therefore also be reduced through so-called weft faults. This would especially occur with the weaving of thicker weft yarns, such as e.g. jute and polypropylene yarns.
With use of the device according to this invention the weft is in the course of a weft cancellation not subject to frictions. The wefts can consequently be held sufficiently under tension in order to prevent weft faults, and are not withdrawn from the fell of the fabric. The quality of the fabric therefore remains guaranteed, even when weaving with fast-running weaving machines or with interweaving thicker weft yarns.
The device according to this invention is preferably provided with a movable pusher element that can be operated in order to bring a weft into a first and into a second position in relation to the yarn carrier, whereby this can, respectively cannot be carried along by the yarn carrier.
Such a pusher element can be moved by means of a very simple and inexpensive actuator, such as for example an electromagnet with plunger or a pneumatic cylinder. A vertical movement over a rather small height can moreover already be sufficient.
The device according to the invention in a very simple and efficiently operating embodiment comprises a yarn carrier which is connected to the weaving batten of the weaving machine. No expensive and complex drive device is necessary, while the yarn carrier is nevertheless driven in a very operationally safe manner, synchronous with the beating-up movements, in order to bring wefts at the correct moment within the feed area of a weft insertion means.
With another preferred embodiment of the device according to this invention the pusher element is connected to the frame of the weaving machine.
The device according to this invention can also be provided with a yarn carrier which can be operated in order to take a first or a second position, w
Debaes Johnny
Dewispelaere Andre
Creighton Wray James
Falik Andy
N. V. Michel Van De Wiele
Narasimhan Meera P.
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