Textiles: weaving – Weft manipulation – Lays or beat-ups
Reexamination Certificate
2002-07-18
2004-10-05
Worrell, Danny (Department: 3765)
Textiles: weaving
Weft manipulation
Lays or beat-ups
Reexamination Certificate
active
06799609
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a sley apparatus having a sley profile, a reed, and a drive. The sley profile carries the reed and is in active connection with the drive.
Jet weaving machines are characterized in particular in that the insertion of a weft thread into a shed is accomplished with the help of a flowing fluid, such as e.g. in air jet weaving machines with the help of compressed air. In a jet weaving machine of this kind a sley apparatus comprises a sley profile, a reed and a drive, with the sley profile carrying the reed and at least one apparatus which is designated as the main nozzle, and with the sley profile being in active connection with the drive. In this the weft thread is drawn off from a thread supply, which can for example be designed in the form of a drum storage, and accelerated for insertion into the shed by means of the main nozzle, which is fed by the flowing fluid. Additional air nozzles, so-called relay nozzles, which assist the progressing insertion of the weft thread into the shed, are provided at specific spacings along the weft insertion length on the sley profile. In this the main nozzle is in a rotationally fixed connection with the sley profile in order that the progressing weft insertion along the relay nozzles through the shed is not impaired by the pendulum-like movement of the sley apparatus. As a rule, the weft thread is held taut after its arrival until the shed is closed.
Under certain circumstances it proves advantageous to use a so-called tandem nozzle for the weft insertion in addition to the above-mentioned main nozzle. The tandem nozzle is placed in series ahead of the main nozzle. This arrangement corresponds substantially to two main nozzles which are placed one after the other with the purpose of achieving the introduction of the force for the thread transport via an increase of the thread surface on which the air acts. In this the tandem nozzle mainly takes over the unwinding of the weft thread from the drum storage, through which the unwinding resistance is compensated. Through this the pressure at the main nozzle can be diminished, which results in a more careful insertion of the web.
On the other hand, with a constant or higher pressure level of the main nozzle, the weft insertion speed or weft insertion time respectively can be varied in such a manner that depending on the weft material to be inserted and the weft thread length, i.e. the cloth draw-in width, a maximum weft-meter performance can be realized with the highest demands on the cloth quality.
Essentially two variants are known for the re-equipping of the sley profile from one main nozzle to a combination of a main nozzle with an additional tandem nozzle as a pre-nozzle. Either the tandem nozzle is fixedly connected to the frame of the weaving machine in a stationary manner by means of a holder section, or in this case the main nozzle is moved relative to the tandem nozzle during the weaving process. However, undesirable thread deflection points necessarily result with corresponding friction and the accompanying effects. In addition to this a second variant with a longer sley profile permits the reception of the main nozzle and the tandem nozzle. In this case there results a massive problem during the change back to only one main nozzle. Then, namely, in operation without the tandem nozzle, an additional unnecessary mass of the unused section of the sley profile must be co-moved, which can become highly problematical in particular at higher speeds of rotation of the machine.
The prior art for the arrangement of the main nozzle and the tandem nozzle on the sley profile will be explained in more detail in the following with reference to
FIGS. 1
to
3
on the basis of several examples. To distinguish the prior art from the sley apparatus in accordance with the invention, the reference symbols in
FIGS. 1
to
3
are provided with primes.
FIG. 1
shows a tandem nozzle
8
′, which is connected stationarily to a holder profile part
5
′. In this the holder profile part
5
′ is in turn firmly connected to the frame
5
″ of the weaving machine. Since the sley profile
1
′ with the reed
2
′ and the main nozzle
6
′ carries out pendulum movements about the axis of the drive shaft
3
′ in operation, for the purpose of beating up the weft thread, there necessarily result undesirable thread deflection points with the corresponding friction necessarily resulting between the stationary tandem nozzle
8
′ and the main nozzle
6
′, which is moved with the sley. This leads to the known negative accompanying phenomena such as the production of additional frictional heat and to increased mechanical tensions in the thread, which fluctuate strongly in magnitude. As a result the advantages, such as for example the reduction of the weft insertion time, i.e. increase in the weft insertion speed, which are achieved through the use of the tandem nozzle as a relieving pre-nozzle, are at least partly compensated again. In certain cases the negative accompanying phenomena as a result of the additional thread deflection points between the tandem nozzle and the main nozzle are so severe that in sum total the stresses on the weft thread even increase and therefore the use of a tandem nozzle as a pre-nozzle in a stationary arrangement cannot be allowed.
To avoid undesirable thread deflection points between the tandem nozzle
8
′ and the main nozzle
6
′ the pre-nozzle can likewise be mounted on the sley profile
1
′ in accordance with FIG.
2
. Then however the sley profile must be made longer. Admittedly additional thread deflection points between the tandem nozzle
8
′ and the main nozzle
6
′ are thereby avoided, because the tandem nozzle
8
′ is now co-moved synchronously in rotationally fixed connection with the main nozzle
6
′.
However, a massive problem results here in the change back to only one main nozzle
6
′, or when the cloth width is to be reduced to such an extent that enough room for the positioning of the tandem nozzle
8
′ and the main nozzle
6
′ would be available on the sley profile
1
′ even without the use of a longer sley profile
1
′. A situation of this kind is shown in an exemplary manner in
FIG. 3
, with it naturally being possible for the tandem nozzle
8
′ to be absent. Here the problem arises that undesirable additional masses must be co-moved. Enormous acceleration forces thereby arise through the pendulum-like movement of the sley profile during the weaving process which, if they are not to exceed certain limits, can make a reduction of the speed of rotation of the motor compulsory and/or can lead to the premature abrasion of corresponding machine components as a result of the additionally arising forces, for example in the form of bearing forces. Thus on the one hand the weft insertion performance is reduced and on the other hand maintenance intervals are shortened and the lifetime of mechanically stressed machine components is significantly reduced, through which the economical operation of the weaving machine is at least impaired. Moreover, additional thread guiding elements
9
′ must be used on removal of the pre-nozzle from the unshortened sley profile for the guidance of the weft thread in order to prevent a collision of the weft thread with the sley profile (see FIG.
3
). Additional thread deflection points with the corresponding negative frictional effects thereby arise.
SUMMARY OF THE INVENTION
It is therefore an object of the invention to propose an improved sley apparatus for weaving machines which permits alternatively the ideal use either of one main nozzle alone or of a main nozzle in combination with a further tandem nozzle which is executed as a pre-nozzle. The problems which are known from the prior art should be avoided in order to arrive at a solution which is on the whole technically and economically more advantageous.
In the sley apparatus satisfying this object the sley p
Baumann Heinz
Scorl Hans-Dieter
Sultex AG
Townsend and Townsend / and Crew LLP
Worrell Danny
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