Textiles: manufacturing – Thread finishing – Surface modification of running length
Reexamination Certificate
2001-04-09
2003-03-25
Worrell, Danny (Department: 3765)
Textiles: manufacturing
Thread finishing
Surface modification of running length
Reexamination Certificate
active
06536087
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a method and an apparatus for continuously unwinding a yarn from a feed yarn package, as well as a method and a texturing machine for texturing a synthetic multifilament yarn.
Various methods and apparatus for unwinding a yarn are known and used in textile machines, wherein a yarn is withdrawn from a feed yarn package and treated or processed. In so doing, the yarn is continuously unwound from the feed yarn package, and advanced to the subsequent process. To ensure a continuous process sequence, the trailing yarn end of the feed yarn package is knotted to the leading yarn end of a second feed yarn package, which is referred to as a reserve package in the present application. Thus, after unwinding the feed yarn package, an automatic change occurs to the reserve package, whose trailing yarn end is in turn knotted to a leading yarn end of a further package, so that the process operates continuously. However, in the subsequent treatment or processing of the yarn, the knot-type piecings constitute problem spots, which may lead to defects in the finished product. In the extreme case, the piecing may separate, so that a yarn break results.
In the texturing of a yarn, the yarn undergoes an intensive treatment during processing. In this process, a crimped yarn is produced from a flat yarn. To this end, as is known, for example from EP 0 641 877 and corresponding U.S. Pat. No. 5,644,908, the yarn is twisted and, for purposes of setting, it is heat treated in its twisted condition. In so doing, the piecing between a trailing yarn end of a feed yarn package and a leading yarn end of a second feed yarn package (reserve package) influences the twist distribution, which results in an irregular crimp. In the further processing of the crimped yarn, such defects may lead, for example, to dye imperfections.
It is therefore an object of the invention to provide a method and an apparatus of the initially described kind for continuously unwinding a yarn, which ensure that a yarn of uniform quality is supplied to a subsequent process.
A further object of the invention is to make available a method and a texturing machine for texturing a synthetic yarn, for purposes of producing from predetermined feed yarn packages with a flat yarn defined packages with crimped yarn, which can be associated to the feed yarn package.
SUMMARY OF THE INVENTION
The above and other objects and advantages of the invention are achieved by the provision of a method and apparatus wherein the yarn is serially withdrawn from the feed yarn package and the yarn reserve package so that the withdrawn yarn is transferred from the yarn feed package to the yarn reserve package. Also, a sensor is provided which senses when the withdrawn yarn is transferred from the feed yarn package to the yarn reserve package, and the sensor then generates a responsive signal.
The invention distinguishes itself in that after unwinding the complete feed yarn package, a signal is generated. This indicates, for example, to an operator that a change of the feed yarn is imminent in the treatment or processing operation. Thus, there exists a correspondence between the finished or end product and the feed yarn package. The operator is able to initiate measures for purposes of avoiding possible occurrences of defects because of the knot-type piecing in the yarn. To detect a change from the feed yarn package to the reserve package, a sensor is used which indicates the transition of yarn from the feed yarn package to the reserve package (yarn change) by emitting a signal. To this end, it is basically possible to use three different embodiments of the method according to the invention. In a first embodiment of the method, the yarn continuously advances through the sensor. To this end, the sensor is designed and constructed such that it generates a signal, when a knot-type piecing passes by, which represents the trailing yarn end of the feed yarn package and the leading yarn end of the reserve package. This embodiment of the method has the advantage that the yarn can be scanned independently of the location in any location along the machine. Likewise, it is possible to use a device of the subsequent process, which detects a process parameter, for example, a yarn tension. In this process, the discontinuity of the signal of the device is evaluated for indicating the passage of the piecing.
In a further advantageous embodiment of the method, only a partial length of the yarn, which comprises a yarn length at the trailing end of the feed yarn package and a yarn length at the leading yarn end of the reserve package, advances through the sensor. To this end, the sensor is arranged between the feed yarn package and the reserve package. Since during the unwinding of the feed yarn package, the trailing yarn end of the feed yarn package and the leading yarn end of the reserve package extend in a loop loosely between the two packages, this variant of the method provides a possibility of scanning the yarn only directly before the yarn change. This minimizes the influence of scanning on the yarn.
A particularly simple and effective development of the invention is given by the further embodiment wherein the trailing yarn end of the feed yarn package and the leading yarn end of the reserve package are stopped, while unwinding the feed yarn package. It is thereby possible to use the movement of a yarn length in the region for signaling the yarn change. This embodiment of the method is characterized in particular in that it requires simple apparatus components for carrying out the method. To this end, the yarn length may be inserted, for example, in a sensor, which generates a signal, as soon as the yarn length no longer contacts it.
At this point, it should be mentioned that the method can be carried out using a variety of designs for the sensor. Thus, for example, it is possible to use mechanical, optical, or capacitive sensors, which generate an electrical, mechanical, or pneumatic signal.
To alert an operator of the signal, it is further proposed that the signal activates a signaler for a visual or acoustic display.
In a particularly advantageous further development of the invention, the signal is supplied to a control unit of the process for purposes of preparing or initiating an intervention in the process. This embodiment of the method is of advantage in particular in the case of automatic process sequences. Thus, it can be realized that, for example, the empty feed yarn package is replaced with a new package, the leading yarn end of which is knotted to the trailing yarn end of the reserve package. With that, it is likewise possible to document the yarn change, in that, for example, the position and the time are registered and stored. These data may form the basis for a further evaluation in quality management.
In processes wherein the piecing leads to occurrences of defects, or wherein it is necessary to maintain a correspondence between the feed yarn and the finished or end product, the embodiment of the method will be especially advantageous, wherein in the event of an unanswered signal, the process will be interrupted for a period of time. For example, in a texturing process, a flat feed yarn is textured in the process and subsequently wound as a textured or crimped yarn on a package. In machines of this kind, a plurality of end packages are wound with a crimped yarn from one feed yarn package. To this end, it is necessary that a package doff be performed in the takeup. During the package doff, a suction device removes the processed yarn to waste. The invention makes it now possible to initiate in such machines a package doff in the takeup in a purposeful manner. The special advantage lies in that it is possible to remove as waste the partial length of the yarn that contains the piecing.
A further advantageous development of the invention provides that in the subsequent process a monitoring mechanism is activated, which detects certain quality parameters for maintaining a uniform quality. With that, it is possible
Alston & Bird LLP
Barmag AG
Worrell Danny
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