False twist texturing machine

Details False twist texturing machine False twist texturing machine

1998-11-05

2001-03-13

Calvert, John J. (Department: 3741)

Textiles: spinning, twisting, and twining

Apparatus and processes

False twist device

C057S058860, C057S105000, C057S238000, C057S244000, C057S252000, C057S264000, C057S284000, C057S285000, C057S332000, C057S334000, C057S336000, C057S341000

Reexamination Certificate

active

06199361

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a false twist texturing machine which imparts a false twist in a filament yarn through a friction of a rotating member like a nip twister or a friction disk, producing a crimped processed yarn.
BACKGROUND OF THE INVENTION
A conventional false twist texturing machine is provided with a plurality of false twist texturing units, and false twisting is carried out by passing the yarn along as it is false twisted by the false twist texturing units. A false twist texturing unit in such a conventional false twist texturing machine looks like the example shown FIG.
4
. This conventional false twist texturing machine is comprised of a plurality of false twist texturing units
1
arranged in a row perpendicular to the plane of the page. Each false twist texturing unit
1
is provided with a first feed roller
4
which draws the yarn Y (filament yarn) from out a supply package
3
held in a creel stand
2
. In the conventional false twist texturing machine, the first feed roller
4
is arranged such that it receives driving force from a line shaft shared by all false twist texturing units
1
, and all the false twist texturing units are driven at a common rotary speed.
A yarn Y, which passes in sequence from the first feed roller
4
to a first heater
5
and to a cooling plate
6
is imparted with a false twist by a false twist device
7
(a nip twister). The yarn Y imparted with the false twist then passes sequentially through a yarn tension detection unit
15
, a second feed roller
8
, a second heater
9
and a third feed roller
10
. It is then wound into a package
12
by a winding device
11
, completing the false twist texturing process.
The false twist device, that is, nip twister
7
, as shown in the enlarged view of
FIG. 5
, is provided with a pair of crossed belts
13
,
14
which nips the yarn Y, propelling and twisting the yarn Y. The twist created by the nip twister
7
is transmitted as far as the first feed rollers
4
and is heat-set by first heater
5
. In other words, the nip twister
7
causes the upstream side to become the twisted side and the downstream side to become the untwisted side.
Thus, the belt-type nip twister
7
is arranged such that it nips the yarn Y using two endless belts that are crossed in contact with each other. By rotationally driving each belt, the yarn Y can be passed along and twisted. Both the nip pressure (contact pressure) of the belts and the rotational speed (the belt surface speed) affect the yarn tension T
2
of the downstream (untwisted) side. The tension T
2
of the untwisted yarn Y, in turn, affects the quality and characteristics of the yarn Y after it is untwisted. Additionally, changes in the running time of the belt also alter the tension T
2
of the untwisted yarn Y, even if the nip pressure and rotational speed remain constant.
Normally, by adjusting the nip pressure and maintaining the constant tension T
2
of the untwisted yarn Y
2
, the quality and characteristics of the yarn Y are kept constant. Specifically, as shown in
FIG. 4
, the yarn tension detection unit
15
for detecting the tension T
2
of the untwisted yarn Y is provided on the downstream side from the belt type nip twister
7
to constantly monitor the tension T
2
of the untwisted yarn Y. To control the tension T
2
of the untwisted yarn Y, a target tension is pre-set and the detected tension T
2
of the untwisted yarn Y is compared against the target value. If the detected value differs from the target value, the nip pressure of belts
13
and
14
are adjusted based on the disparity. When the nip pressure of the belts
13
,
14
is adjusted, the tension T
2
of the untwisted yarn on the downstream side is altered. Thus, it is possible to have the detected tension value approximate the target value.
There is variation, however, in the yarn quality of the packages
12
produced among the different false twist texturing units
1
, as well as within the packages
12
of the same unit
1
, in the conventional false twist texturing machine. The causes of this variation are mainly the mechanical or yarn supply-related problems. The mechanical causes are yarn slippage at the feed rollers
4
and positional differences between the upper and lower levels of the supply packages
3
in the creel stand
2
. The supply-related cause is that there is variation in the degree of elongation of the individual yarns supplied to the false twist texturing units
1
. This variation occurs when different supply packages
3
are used, or as the yarn is taken off the same supply packages
3
.
When there is variation in the condition of the supply side yarn due to such mechanical or supply-related problems, the tension T
1
of the yarn between the first feed roller
4
and the false twist device
7
(tension of the twisted side) changes, and thus variation of the tension T
1
between the false twist texturing units
1
arises even if the yarn is drawn at a constant draw rate (the ratio of the surface speed of the second feed roller
8
to that of the first feed roller
4
) at the false twist texturing units
1
. As a result, the yarn quality varies between each false twist texturing unit
1
, and further, varies within each wound package
12
. This occurs even with conventional control systems that keep the tension of the untwisted yarn T
2
constant.
SUMMARY OF THE INVENTION
In order to eliminate these problems and improve the conventional technology, it is an object of the present invention to provide a false twist texturing machine which can eliminate the variations in yarn quality between wound packages.
The means employed by the present invention to appropriately control a yarn tension in an upstream side from a false twist device is a false twist texturing machine comprised of a false twist device for imparting the yarn with a false twist, a first feed roller arranged on the upstream side from the false twist device, and a yarn tension control device for automatically controlling the rotation speed of the first feed roller relative to the yarn tension of the upstream side.
Thus, since the false twist texturing machine of the present invention controls the speed of the first feed roller in relation to the yarn tension of the upstream side from the false twist device, the yarn tension of the upstream side can be appropriately controlled, and variations in the yarn quality of the wound packages can be eliminated.
Specifically, either an upstream side yarn tension control device that automatically controls the rotation speed of the first feed roller such that the yarn tension of the upstream side from the false twist device is maintained within a fixed range, or a yarn tension ratio control device which automatically controls the rotation speed of the first feed roller such that the ratio of the yarn tension of the upstream side from the false twist device to the yarn tension of the downstream side from the false twist device is maintained within a fixed range may be employed as the yarn tension control device.
The means employed by the present invention to maintain an appropriate tolerance range for the draw rate of the yarn is a false twist texturing machine in which an upstream side yarn tension control device can set an upper limit and a lower limit within which the rotation speed of the first feed roller can change.
Consequently, in the false twist texturing machine of the present invention, the ratio of the speed (draw rate) of the second feed roller arranged on the downstream side from the false twist device of the first feed roller is appropriately adjusted within a permitted range, and variations in the yarn quality of the packages are eliminated.
Specifically, the upstream side yarn tension control device which automatically controls the rotation speed of the first feed roller such that the yarn tension of the upstream side from the false twist device is maintained within a fixed range, or a yarn tension control device which automatically controls the rotation speed of the first feed roller such that the ratio of

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