Textiles: weaving – Warp manipulation – Shedding
Reexamination Certificate
2001-10-25
2002-11-12
Vanatta, A (Department: 3765)
Textiles: weaving
Warp manipulation
Shedding
C139S055100, C139S06600A
Reexamination Certificate
active
06478055
ABSTRACT:
This invention relates to a shed forming device, such as for instance a jacquard machine, comprising at least one shed-forming element to determine the positions of one or more warp yarns on a weaving device, a lifting means provided for moving up and down the shed-forming element, and at least one actuator provided for selectively influencing the shed-forming element, so that it either stays at a fixed height, or is moved by the lifting means.
More particularly this invention concerns a weaving device provided with a shed-forming device according to this invention.
In addition, a shed-forming element (e.g. a hook) for determining the positions of one or more warp yarns on a weaving device, which has been provided for being selectively influenced by an actuator of a shed-forming device, is within the scope of this invention. More particularly such a shed-forming element has then been provided to be selectively influenced by an actuator or/and a shed-forming device according to this invention.
Shed-forming devices with the characteristics mentioned above are well known and are mainly used to form a shed during successive weaving cycles on a weaving machine each time between a series of warp yarns, in which the warp yarns take up such a position with respect to one or more inserting levels, that after having inserted the weft warp yarns on this inserting levels a fabric is formed having the structure desired and possibly the design or pattern desired.
A known shed forming device—which has been described in GB 2 047 755—is a two-position-open-shed jacquard machine on which the warp yarns may be brought at two heights and which allows during each cycle either to keep those warp yarns (according to the open-shed principle) at the same height as during the preceding cycle or to bring them at a different height, as desired.
For that purpose, this device disposes of two knives which may be moved up and down in opposition and a series of sets of two co-operating shed-forming elements, called hooks, which may be moved up and down by a respective knife and which in their upper position may be elastically deformed by means of electromagnets in order to hook on to a holding lutch provided for at a fixed height. The shed-forming elements are connected to each other by a pulley cord thrown around and led under a pulley of a pulley element. The pulley element itself is connected to one or more harness cords, which, in turn, are connected to their respective warp yarns.
By making the hooks and the knives moving up and down or by selecting one of the hooks in its upper position, so that it is held in the upper position, the warp yarns my be brought into or kept in one of two different positions during each cycle.
In EP 0 214 075 a similar two-position-open-shed shed-forming device is described. This device differs from the device described above, in that the pulley element now comprises an upper and a lower pulley, where the pulley cord, connecting the two hooks is thrown around the upper pulley and a second pulley cord is thrown around the lower pulley from a fixed fastening point and is further connected to the warp yarns and in that the selection of the hooks in their upper position may now occur by an elastic deformation of two strips with hook-shaped extremities by means of an electromagnet.
Both devices function with a pulley device and pulley cords. This system has several disadvantages. Rolling the pulley cords off the pulleys causes the pulley cords to wear out so that they might break easily. The pulley elements function in the dusty environment of a weaving mill, as a result of which they will get jammed by the effect the dust has on their bearings. At the high working speed of modern weaving machines, the pulley devices develop frictional heat, which has a negative influence on the duration of the pulley cords and a ventilation device should be provided for, in order to evacuate this heat. Furthermore replacing parts of these pulley device (pulley cords, pulley elements) in case of break or wear is a particularly time consuming job.
The first purpose of this invention is to provide for a shed-forming device for a weaving device, having none of the disadvantages mentioned above.
There are shed-forming devices which function without a pulley device and which do not show the above-mentioned disadvantages. Such a pulleyless shed-forming device was described, among others, in EP 0 779 384.
This shed-forming device works with a U-shaped flexible hook, which is connected to one or more harness cords without a pulley element intervening and of which the upper part of the two legs has the shape of a hook and on which respective knives may hook to be moved upwards, with the hook resting on a bottom board. The knives move up and down in opposition. An electromagnet, situated between de legs of the hook is used to bend the hooks elastically towards each other, so that the hook-shaped extremities of these legs get outside the pick-up range of the knives. In BE 9800036 and BE 9800035 also, similar shed-forming devices are described.
However, these pulleyless devices have a new problem, namely when a hook is coupled with one leg to a rising knife, then the other descending knife will hit the top of the other leg of the rising hook, and when one leg of a hook is coupled to a descending knife, then the other rising knife will pick up again the descending hook at the hook-shaped extremity. To avoid these unwanted phenomena, the known devices provide for a supplementary control with the intention to make the hook leg concerned give way in these critical moments.
This avoiding movement has to be performed each time at full speed of the moving hook. This makes the control rather complicated and consequently the moving hooks will suffer from supplementary friction with more production of neat. Moreover, the devices described are insufficiently suitable to adapt the lifting of the hooks and to adjust the inclination of the shed to be for med.
In addition, the electromagnet is expected to influence the position of a hook leg over its entire length. For that purpose, a rather large passing space is needed for the hook legs as a result of which the electromagnets have to work with a rather large air gap and as a result of which the selection system is no longer able to function with sufficient efficiency. In order to increase efficiency, stronger electromagnets are needed, but they have the disadvantage that they consume quite some electric energy.
A second purpose of this invention is to provide for a shed-forming device with the help of which the disadvantages of the known pulleyless shed-forming devices mentioned above may be remedied.
According to this invention the objects mentioned above are obtained by providing for a shed-forming device comprising at least one shed-forming element to determine the positions of one or more warp yarns on a weaving device, a lifting means provided for to move the shed-forming element up and down, and at least one actuator provided for to influence the shed-forming element selectively, so that it is either kept at a fixed height or is moved by means of the lifting means, and of which, according to the invention, each shed-forming element comprises at least one selection body which, in order to obtain said selective influencing, may be put, as desired, in a first or in a second stable position by means of an actuator.
Of course, the said aims are likewise achieved by providing for a shed-forming element to determine the positions of one or more warp yarns on a weaving device having the characteristics mentioned above. A shed-forming element that has been provided for to be selectively influenced by an actuator of a shed-forming device and that comprises, according to his invention, at least one selection body, whereas this selection body, for the said selective influencing, as desired, may be put in a first or second stable position by means of the actuator, and is therefore in itself an object of this invention.
Because the said positions of the selection body are stabl
Creighton Wray James
Muromoto, Jr. Robert
N.V. Michel Van de Wiele
Narasimhan Meera P.
Vanatta A
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