Textiles: spinning – twisting – and twining – Apparatus and processes – Twist setting
Reexamination Certificate
1999-08-19
2001-10-16
Calvert, John J. (Department: 3765)
Textiles: spinning, twisting, and twining
Apparatus and processes
Twist setting
C057S005000, C057S239000, C057S328000, C057S333000
Reexamination Certificate
active
06301870
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a false twist texturing machine for texturing a multiplicity of thermoplastic threads together with a process for producing a textured thread.
A false twist texturing machine of this kind is known from U.S. Pat. No. 5,644,908. In this false twist texturing machine a thread is drawn off from a feeding spool by means of a first delivery device and run in a false twist zone. In the false twist zone are disposed a heating device, a cooling device and a false twist unit. Within the false twist zone a drawing and fixing of the thread takes place. The false twist unit produces a twist which runs in the opposite direction to that of the thread, so that within the cooling device and the heating device, in which a thermal treatment of the thread takes place, the latter exhibits a twist. The thread is after the false twist unit drawn off by a second delivery device and run to a second heating device for the thermal after-treatment. The thread is then run-out of the second heating device by means of a third delivery device and conveyed to a take-up device in which the thread is wound onto a spool. In order to wind on as twist-free a thread as possible, there is provided with the known false twist texturing machine between the third delivery device and the take-up device a vortexing nozzle. In so doing the residual twist contained in the thread is eliminated.
There is known through EP 0 532 458 B1 a false twist texturing machine in which a thread is fed to a false twist zone. In the false twist zone are disposed a first heating device and a false twist unit. The false twist unit produces a twist which runs in the opposite direction to that of the thread. The thread is after the false twist unit run to a second heating device. Downstream of the second heating device is connected a blow nozzle which again imparts a false twist to the yarn, namely in a direction which is opposite to that of the twist produced in the false twist unit.
The problem is encountered with swiftly running threads, however, that the amount of the residual twist increases with the thread speed. In this case the residual twist is imprinted in the thread by the relaxation treatment which has taken place in the second heating device, and it cannot be removed by vortexing.
The present invention is based on the object of developing the false twist texturing machine of the type described above and the process in such a way that the thread is coilable twist-free irrespective of the thread speed.
SUMMARY OF THE INVENTION
The above and other objects and advantages of the invention are achieved by the provision of a yarn false twist texturing machine for texturing a multifilament synthetic thread or yarn comprising a yarn feeding spool, a first delivery device, a first heating device, a cooling device, a false twist unit, a second delivery device, a second heating device, a third delivery device, and a winding device serially arranged along a yarn path of travel. A yarn counter-twist device is positioned between the second heating device and the third delivery device for imparting twist to the yarn in a direction opposite to that imparted by the false twist unit and such that the counter-twist device and the second heating device are linearly aligned and the yarn runs in a straight yarn path therebetween, and so as to produce an essentially twist-free yarn.
The invention is characterised in that the counter-twist in the opposite direction produced by the counter-twist apparatus can run back unimpeded into the second heating device in the opposite direction to that of the thread, i.e. yarn. For this the counter-twist apparatus is arranged in the thread path upstream of the third delivery unit in such a way that the counter-twist apparatus and the second heating device lie in one plane. The thread is thus run in a straight thread path between the heating device and the counter-twist apparatus. The counter-twist produced returns undiminished in the opposite direction to that of the thread until it reaches the second delivery device. It is thus ensured that the thread is already twist-free during the heat treatment for the relaxation. A fixing of a residual twist caused by the false twist unit is prevented. The counter-twist apparatus can in this case produce in the thread a counter-twist by friction, for example by means of discs or straps on the running thread. Since the counter-twist apparatus has to apply a substantially smaller torque to the thread compared with the false twist unit, the counter-twist could also be formed by a roller overrunning obliquely from the thread.
In a particularly advantageous development of the invention, the counter-twist apparatus is arranged directly at the outlet of the second heating device. The counter-twist is consequently introduced in the heated thread. In the heated state the thread possesses a higher elasticity, so that the introduction of the counter-twist is possible with less expenditure of energy.
The construction of the counter-twist apparatus as a vortexing nozzle is particularly preferably applicable here, since as a result of the tangential entering of the air current into a thread channel, first of all, the counter-twist is produced in the thread, and secondly a cooling of the thread is simultaneously effected. A further advantage of this construction of the false twist texturing machine according to the invention lies in the fact that the texturing and hence the bulkiness of the thread is supported by the vortexing of the filaments of the yarn.
According to a particularly advantageous development of the false twist texturing machine the vortexing nozzle is arranged together with a thread channel on an axis of a heating tube of the second heating device. The thread can as a result be inserted without difficulty simultaneously in the heater and in the vortexing nozzle.
With the false twist texturing machine a so-called Z twist or an S twist can be produced in the thread by means of the false twist texturing unit. For this the direction of rotation in the false twist unit is modified. In order to use the vortexing nozzle arranged at the outlet side of the second heating device both for the Z twist and for the S twist, the vortexing nozzle is connected to the heating tube of the heating device by a detachable adaptor. The vortexing nozzle is symmetrical with respect to a center plane lying at right angles to the thread channel, so that a reversal of the direction of rotation is possible by transposing the inlet and outlet sides of the vortexing nozzle.
According to yet another advantageous development of the false twist texturing machine it is proposed that the counter-twist apparatus comprises a substantially rotationally symmetrical, rotatable body, via which the thread is run at an angle &agr;, wherein the angle &agr; enclosed by the thread and a normal lying perpendicular on an axis of the body is less than 90°. A regular and reliable introduction of a counter-twist into the thread is obtained by means of such a counter-twist apparatus.
The counter-twist apparatus comprises preferably a cylindrical, rotatable body, via which the thread is conveyed at an angle. With advantage the angle is adjustable. The adjustment takes place preferably by swivelling the axis of the body of the counter-twist imparter.
According to a further advantageous development of the false twist texturing machine it is proposed that the body of the counter-twist apparatus is durable.
The process according to the invention for producing a textured thread is characterised by the fact that the counter-twist is produced in the heated thread directly at the outlet of the second heating zone. The residual twist in the thread can be removed completely in this way, so that a completely twist-free thread can be fed to the winding stage and be wound up. Moreover, the counter-twist can by virtue of the higher elasticity be introduced into the thread in a simple manner without substantial energy supply and hence without substantial modification of the yarn properties,
Bunger Heino
Lorenz Hellmut
Alston & Bird LLP
Barmag AG
Calvert John J.
Hurley Shaun R
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