Counter for Synthetic Fiber Yarns

Transcription

1 Development of a Filament Counter for Synthetic Fiber Yarns By Kazutomo Ishizawa, Katsumi Miyawaki, Tohru Koide and Tamotsu Kondo, Members, TMSJ Kanebo, Ltd., Miyakojima-ku, Osaka Based on Journal of the Textile Machinery Society of Japan, Transactions, Vol. 31, No. 7, p (1978-7) Abstract It is very important to detect and eliminate yarns having irregular number of filaments. Formerly, it was done by spreading them manually and counting visually the number of filaments one by one. In order to reduce manpower needed for this manual examination and to improve the reliability of the examination, we developed a new method by which the filaments are arranged in a single layer closely packed and parallel on a stage with a saddle style guide. Then the number of filaments is automatically counted with a photo-electric device. It improves the working efficiency by 5-6 times. 1. Introduction Synthetic multi-filament yarns are composed of many filaments, the number of which is predetermined. But, owing to several troubles during production, some filaments may be cut down or jumped in, causing multi-filament yarns having too many or too small number of filaments. Especially in modern high-multi spinning through many nozzles on one spinning head, the possibility to find irregular number of filaments is apt to increase. However, these irregular-filament yarns look normal in both spinning and thereafter processes because one or two lost filaments cannot easily be recognized in such a yarn. Also, irregular-filament yearns are seldom noticed in weaving or knitting process. Generally, the irregularity of the filament number is found after dyeing or finishing process. Although irregular multi-filament yarns are seldom found in a bobbin or a pirn, they are frequently found in weaving or warp knitting as several hundreds or several thousands of filaments are processed at a time, causing warp streaks after dyed in light colors such as light blue or pink, which results in a large quantity of defective product. In case of lapping 10 warp ends from 70 denier 2 kg bobbins, such a defect is found only after 500 rolls of clothes, each 50 m long, have already been produced, and the factory subbers a great loss. From this point of view, checking the number of filaments in yarns is very important. The conventional method for this is as follows ; an operator rubs filaments to separate them each other by electrification, and then count each filament visually. This method is complicated and low in efficiency. Moreover, operators are apt to pass defective filaments as normal. So this method does not fit our aim to reduce manpower keeping the yarn quality high. This report is for increasing the reliability in checking the number of filaments as well as for reducing man-power. 2. Comparison of Counting Methods 2.1 Electric capacitance method Electric capacitance method is widely used for evenness test of natural and synthetic fibers. The principle is to detect 86 Journal of The Textile Machinery Society of Japan

2 the increase of electric capacitance caused by inserting filaments between a pair of electrodes. In this case, the moisture content should be constant, because the dielectric constant of water is times as large as that of filaments. In winding up synthetic fibers, spinning oil is usually fed to filaments about 1 % by weight, which is mainly water and oil mixed emulsion. Though spinning oil is supplied to each filament evenly in high accuracy, moisture may soon vaporize or move from layers to layers of multi-filament bobbins. Therefore, electric capacitance method may be adequate for measuring fluctuation of filament fineness, but is not suitable for measuring filament number. For instance, Figs. 1 and 2 show Uster % records of two multi-filament yarns having the same number of filaments. The averages differ by a value more than equivalent to a single filament. 2.2 Successive breaking method. When we stretch synthetic multi-filament yarns, each filament is broken one by one untill all of filaments are broken as shown in Fig. 3. When more than one filament are broken simultaneously, we can distinguish the number of broken filaments if it is not over three. If it is over four, we connot determine the number of filaments accurately, because the tension decrease corresponding to each break becomes unequal and fluctuates as shown in Fig. 4. Therefore this method is not suitable when filaments are more than ten. 2.3 Draw tension method Draw tension is a tention which is found when a multifilament yarn is stretched under a given condition. But as its total denier usually varies slightly, draw tension varies as shown in Fig. 5, even if a yarn runs under a given stretch. There are also such factors as exert influence on strainstress characteristic of filament yarns as time goes on. So, the draw tension method is not suitable for checking the number of filaments when several tens filaments are counted. 3. Filament Counter Developed 3.1 To arrange filaments parallel After all, we reached the conclusion that such a method as arranging filaments closely parallel in a layer without gaps Vol. 26 No. 3 (1980) 87

3 between them is the most suitable for counting the number of filaments. To do this, first put filaments around on a circular cylinder set on a stage as shown in Figs. 6 and 7, holding their both ends and stretching by hands, followed by reciprocating them on the cylinder. By so doing, filaments on the stage move from the state shown in Fig. 8 (A) to the state (B), still remaining some gaps between them. By reciprocation both on the cylinder surface and on the valley of the saddle-shaped guide, each filament slides down the slope and gathers to become close parallel in a layer as shown in Fig. 8 (C). Actually only by stretching them, no reciprocation may decrease the gaps and especially so with undrawn yarns. The diameter of the cylinder should be in the range of 5-8 mm. Smaller diameter than this causes less contact area between filaments and the cylinder, resulting in high pressure and inert filament movement. Larger diameter causes larger contact area, resulting in high resistance against filament motion towards the center. So, we decided the cylinder diameter to be 6 mm for practical use. The curvature radius of the valley part of the saddle guide should be as small as possible for arranging filaments in parallel, and we decided this to be 0.25 mmr to fit various denier of synthetic fibers. The material of the cylinder stage must be transparent for photoelectric counting. First, it was made of regular soda glass. But soon after reciprocating filaments on it, it became opaque with TiO2 in filaments. So we adopted for practical use a synthetic sapphire cylinder specially polished. 3.2 Method of counting Though we could arrange filaments neatly close parallel on the cylinder, it was rather hard to count them visually, even if the profile of filaments was enlarged. So we developed such a method as projecting the profile of filaments enlarged times to check the state of arrangement visually. If it is good, the number of filaments is counted photoelectrically. 88 Journal of The Textile Machinery Socie ty of Japan

4 The counting device is shown in Fig. 10: Light is cast from the lower side of the stage cylinder, and after passing through filaments is projected on the screen. Though filaments contain Ti02, it gives no trouble optically, and the light which passes through filaments concentrates in bright lines at A-A' in Fig. 11. These bright lines are projected on the screen as shown in Fig. 12. We can also find a slim filament which is rarely produced in spinning process. When the filamet arrangement on the screen is not perfect, additional reciprocation is necessary. If it is perfect, an operator turns on a foot switch to rotate a motor so that a movable mirror may send the bright lines to a phototransistor one by one through a slit on the upper side of the screen. Circuit is composed of comparatively few flip-flops, logical elements, resistors and capacitors, and can be available to various kinds of multi-filament yarns. The first filament counter we developed is shown in Fig. 16, which can be tiltable to accomodate to various stature of operators. The device shown in Fig. 17 is a more developed one and has the following characteristics; it is for laboratory work and available to dull multi-filament yarns besides semi-dull and bright yarns. Fig. 18 shows the panel part of Fig. 16. In 3.3 Electronic counting device As shown in Fig. 13, the pulse signal from the phototransistor is supplied to Operational Amplifier(OP amp in short) and the output (see Fig. 14A) is differentiated with resistors and capacitors to make it stable (see Fig. 14B). After passing through Comparator (see Fig. 14C), the pulse signal is supplied to Signal Treatment Circuit and Counter. In Fig. 15 is shown the signal treatment circuit within double dotted lines. It has mainly three functions; 1) To reduce one count from signal counts to make them correspond to the number of filaments. This is because a pulse signal is generated when the profile moves from a bright part to a dark one. 2) To remove ambiguous pulses due to such narrow gaps between filaments as cannot be found visually. 3) To indicate Zero count for errornous signals due to oil or dust on the arranging cylinder outside of the filaments. Vol. 26 No. 3 (1980) 89

5 its center there is a projection screen. At the right upper side there is Nixie-tube indicator, and below it a digiswitch to preset the number of filaments to be checked. When this preset value is different from the measured value, a bell rings once to inform something wrong. At the left side of the panel, there are two semi-fixed resistors for OP amp, one is a sensitivity presetting adjuster and the other a manual sensitivity adjuster. Though the image magnification can be changed from 50 to 100 according to filament denier, the sensitivity of op amp is kept moderate by changing over the circuit to each corresponding semi-fixed resistor. Manual sensitivity adjuster is only used when we check special filaments. To preset the semi-fixed resistor, it is sufficient only to set the sensitivity at the maximum to the extent that the output signal of OP amp is not saturated. This is done by watching a light emitting diode (LED) being ignited and the other LED is not ignited which are on the left upper side of the panel. 4. Examples of Filament Counting Now are used 20 sets in our plants for nylon and polyester, and 46 sets in dometstic and foreign synthetic fiber producers. Our experience is as follows; though some skill is necessary to arrange filaments parallel, 10 minutes training is sufficient to set within 5 to 10 seconds a yarn of less than 20 filaments. After 2-3 days later, it is done within 1 to 5 seconds. At present, most operators can set filaments in such a momentary action as 1-2 seconds. When the number of filaments is over 20, it takes longer time. But it is not so difficult for female operators to set a yarn D, Fil. within 3-4 seconds. When filaments are more than 50, it is rather difficult and takes longer time. To solve this difficulty, we put on attachment to make the saddle guide vibrate. So, a yarn, 100 D, 96 F., can be set within 6-8 seconds. The Nixie-tube indicator has a two-figure decimal display, and can indicate the number up to 99. The total time for counting is the sum of the time above mentioned and two seconds which is necessary for the photoelectric counter. S. Conclusion We developed such a filament counter as follows; filaments are arranged on a circular cylinder in a flat layer and their total number is counted photoelectrically. By this device we could increase the filament checking efficiency by 5-6 times as compared with before, and reduced a large amount of female operators mainly engaged in this operation. Even those men-operators who were said hitherto not fit for checking filaments can easily do checking. So the mid-night check work in which female operators are prohibited to engage can be carried out by men-operators, which makes the product flow in a factory smooth. To get more manpower reduction, a checking device set on a producing machine and operated without human judgement is needed, and we are now trying to make it. But for the present, the semi-manual and semiautomatic filament counter we developed seems to be widely used because manpower reduction and quality improvement which will be obtained by this device are very large compared with the device cost. This filament counter is on sale through Kanebo Engineering Ltd., and the export to U.S., Europe, Middle East and Korea is increasing recently. The fact that the devices are bought by the countries where labor cost is comparatively low, suggests that those countries are endeavoring to improve the quality of sythetic fibers. 90 Journal of The Textile Machinery Society of Japan