JPS6146571B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an untwist detection method for detecting the occurrence of untwist in a manufacturing process of a false twisted crimped yarn of synthetic fiber. Incidentally, untwisted refers to a portion of a false-twisted crimped yarn where false-twisted and crimped single fibers are not untwisted and entangled, resulting in abnormal crimp.

In general, the quality of the processed yarn obtained when synthetic fiber yarn is subjected to draw false twist crimping processing using a draw false twist processing machine is determined by processing conditions such as the number of false twists, heating temperature, etc., and the raw yarn to be processed. This is largely affected by quality abnormalities such as fuzz and loops, damage to the yarn guide of the drawing false twisting machine, and mechanical defects such as scratches on the disk of the false twisting unit. The quality of such false-twisted crimped yarn is evaluated from various aspects such as fineness, strength, elongation, crimp performance, etc., and crimp performance is particularly important as a quality of false-twisted crimped yarn.

In such crimp performance, there is untwisting which, if it occurs, will cause a serious quality abnormality. Conventionally, in order to prevent this untwisted part from being mixed into the product yarn, a yarn quality inspection process was set up, and quality control was carried out by sampling a large number of sample products from the product yarn package.
There is a problem in that the number of items to be tested is large and the testing work is troublesome, requiring a lot of manpower. Furthermore, the inspection of yarn quality in the inspection process is only a sample inspection of a very small part of a single sample product, and it is extremely difficult to detect abnormalities in yarn quality that mostly occur temporarily, such as untwisted yarn. There's a problem.

In order to solve this problem, the present inventors previously proposed the following crimp abnormality detection method in Japanese Patent Application No. 57-149863. This method monitors tension fluctuations in the yarn during the false twisting and crimping process in the manufacturing process of false twisted and crimped yarn, and detects yarn crimp abnormalities based on the occurrence of pulse-like fluctuations in the tension. ,
Since the above-mentioned untwisted parts can be detected online, quality control is complete and the inspection process can be omitted, which is an excellent method.

However, if untwisted fibers are detected using the method disclosed in Japanese Patent Application No. 149863/1982, minute untwisted fibers that pose no practical problem will also be detected. When monitoring untwisted yarn online, detecting minute untwisted yarns that do not actually harm yarn quality poses the following problems in terms of yarn quality management. In other words, if untwisted yarn is detected, unless it is possible to distinguish between untwisted yarn that causes actual damage to yarn quality and untwisted yarn that does not cause any actual damage to yarn quality, untwisted yarn that does not cause any actual damage to yarn quality may occur. There is a problem in that the product yarn is treated as inferior quality, the rate of inferior quality increases accordingly, and productivity decreases.

The present invention was made in view of such problems,
The present invention provides an untwist detection method that can discriminate the strength (size) of untwist that has occurred and reliably detect only untwist that poses a practical problem.

That is, the present invention monitors the tension fluctuation of the yarn in the stretch false-twisting processing area of the stretch false-twisting processing machine when synthetic fibers are stretch-false-twisted by the stretch-false-twisting machine, and the tension fluctuation is adjusted to a predetermined level. This untwisted detection method is characterized in that the untwisted state is detected when it continues for a predetermined period of time or more at a threshold value or more.

Hereinafter, details of the present invention will be explained with reference to the drawings.

FIG. 1 is an explanatory diagram of a drawing false twisting machine according to the present invention, and the false twisted crimped yarn is manufactured as follows. The yarn Y is unwound from the yarn package 1,
The yarn is fed via the yarn guide 2 from the feed roller 3 to the false twisting and crimp processing area S at a constant speed. In the false twisting and crimping processing area S, the yarn Y is given a predetermined twist by a false twisting means 4 (in this example, a friction disk system is used), and at the same time, the twisting is carried upstream and passed to the heater 5. The material is heat set and false twisted and crimped. The false twisted and crimped yarn Y is taken off at a constant speed by a delivery roller 6, passes through a yarn guide 7, and is formed into a predetermined processed yarn package 9 by a winder 8. Therefore, the thread Y is fed by the feed roller 3.
and the delivery roller 6 while being stretched and false-twisted and crimped. 10 in the figure is a yarn path downstream of the false twisting means, specifically between the false twisting means 3 and the delivery roller 6, so that the tension of the yarn Y in the false twisting and crimping process can be monitored with a tension detector. It is installed on the thread path.

In the draw false twisting machine having the above configuration, the present inventors discovered that when untwisting occurs, the output waveform of the tension detector 10, that is, the yarn tension, as shown in FIG. We found that the value fluctuates rapidly as described below. When the thickness of the yarn, processing conditions, etc. are changed, the specific waveform of the tension fluctuation changes slightly, but the same tension fluctuation as shown in FIG. 2 occurs.

As mentioned above, Japanese Patent Application No. 57-149863 detects on-line the occurrence of untwisted drawn and false-twisted yarn by monitoring the occurrence of such pulse-like tension fluctuations, which has the above-mentioned problem. In addition, even in this method in which the magnitude of the variation in tension is added to the discrimination criteria, even minute untwisted yarns that do not actually harm the quality of the yarn are still detected, although the frequency decreases.

As a solution to this problem, the present inventors:
The pulse-like fluctuation of the thread tension T in Figure 2 is the steady tension.
Focusing on the fluctuation time D during which the amount of fluctuation from T ₀ continues at a predetermined threshold value A or more, the relationship between the visually observed unresolved twisting strength, the peak value H of the tension fluctuation, and the fluctuation time D is artificially determined. Various factors (abnormal quality of raw yarn, abnormal processing conditions, mechanical failure of processing means) causing this were created, and the output of the tension detector 10 was recorded and studied by generating untwisted yarn.

Figure 3 shows the wave height H of tension fluctuation and predetermined threshold value A of 6g under the processing conditions of yarn 75 ^De and processing speed 700 m/min.
It is a relationship diagram of the fluctuation time D during which the above tension fluctuation continues and the stratification results of ununraveled twist strength by manual inspection. The vertical axis of the figure shows the peak value H (g) of tension, and the horizontal axis shows the fluctuation time D (seconds) during which the tension fluctuation of 6 g or more continues when the predetermined threshold value A is 6 g.
〇 and × indicate the stratified ununtwisted strength, ◎ mark indicates a high strength that is considered to be a quality abnormality in practical use, and 〇 and × mark indicate a low or minimum strength that does not cause a quality problem. As is clear from the figure, the untwisted strength marked with ◎ is high and causes actual damage to the yarn quality, the tension fluctuation time D when the threshold value A is 6 g or more is approximately 0.6 ^sec or more, and the unraveled twisted strength marked with 〇 is small. Or 6 for those with no actual damage as extremely small threads of ×
The tension fluctuation time D over 100 g was 0.3 ^sec or less.
In a test example in which the tension peak value H is 6 g or more and the tension fluctuation time D is 0.5 ^sec or more, as shown by the dotted line in the figure, all untwisted yarns that cause actual damage to yarn quality are detected, and none of the untwisted yarns that do not cause any actual damage are detected. It was not detected. That is, by distinguishing the magnitude of the tension fluctuation time D that is greater than or equal to a predetermined threshold value A, it is possible to distinguish between untwisted threads that cause actual damage to yarn quality and untwisted threads that do not cause any actual damage. The above explanation is based on the yarn processing conditions.
The explanation is for the case of 75 ^De , 700 m/min, but such untwist detection conditions (threshold value of yarn tension and tension fluctuation time)
varies slightly depending on the processing conditions of the yarn Y, such as processing tension, processing speed, etc., but the tension fluctuation threshold A is about 10 to 30% of the processing steady tension T ₀ , and the tension fluctuation time D setting value is 0.2 to 30%. We have confirmed that it can be dealt with practically in about 10 seconds. Therefore, it is considered that the variation area of the pulse-like tension fluctuation has a correlation with the unresolved twist strength, and a case where the variation area is equal to or greater than a predetermined value may be regarded as the occurrence of unresolved twist.

Although an example has been shown in which the tension fluctuation occurs in the tension increasing direction, it goes without saying that the present invention can also be applied to a case in which the tension fluctuation occurs in the tension decreasing direction.

As described above, the present invention detects untwisting when tension fluctuations exceeding a predetermined threshold value continue for a predetermined period of time, and not only can detect untwisting that causes actual damage reliably, but also uses a simple device. For example, it is an excellent device that can perform multi-spindle management by processing the outputs of tension detectors provided in various places using a signal processing circuit consisting of a voltage comparator circuit and a time comparator circuit, or a microcomputer. Furthermore, in multi-spindle management, the threshold value and duration, which are quality control levels, are generally common to all spindles, so even if the steady-state operating tension value is different for each spindle, common setting management is possible, and management work can be greatly streamlined. Furthermore, there is no possibility that product yarns with small untwisted yarns, which do not have any problems with yarn quality, will be downgraded, and this has an extremely large effect in terms of production.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of a stretching false twisting machine according to the present invention;
Figure 2 is a graph showing an example of measuring yarn tension fluctuations.
Figure 3 shows the peak value H of tension fluctuation and the tension fluctuation dynamic time D.
It is a graph showing the relationship between the stratification results of the unresolved twist strength and the unresolved twist strength determined by manual inspection. 1 is a yarn package, 4 is a false twisting means, 5 is a heater, 8 is a winder, and 10 is a tension detector.

Claims (1)

[Claims] 1. When synthetic fibers are subjected to draw false twist processing using a draw false twist processing machine, tension fluctuations in the yarn in the draw false twist processing area of the draw false twist processing machine are monitored, and the tension fluctuations are monitored. 1. A method for detecting untwisted yarn, which is characterized in that the untwisted yarn is detected as being untwisted when the value of the untwisted yarn remains at a predetermined threshold value or more for a predetermined period of time or more. 2. The threshold value is 10 to 30% of the steady processing tension,
The untwisted detection method according to claim 1, wherein the predetermined time is 0.2 to 10 seconds.