23
Experimental Study of Travellerless Magnetic Ring Frame
Part 1 : General
By Ichiro Ohno, Member,TMSJ
Japan Wool Texile Co., Ltd., (Nippon Keori K.K.), Kobe
Even the traveller for revolving and twisting During an experiment, we accidentally put the the yarn is dispensed with, the yarn-guiding ring inner ring upside down. The result was that the cannot be omitted. This article relates to a re upper ring floated as shown in Fig. 3. Here again, search on the use of magnetic force as a means to however, the inner ring was attracted to the inside hold guide rings in the air in such a way that it of the outer ring and was biased, but the biasing does not interfere with the revolving movement of force was one-fourth of that in Fig. 2. It was the yarn. made clear that there was no difficulty in letting the yarn pass through the gap between two rings so long as the attracting force was so small. The Device of Magnetic Ring Fig. 4 is an example of the inner ring being held by the circular arrangement of horse-shoe type magnets. This example shows six permanent Take two rings made of a magnetic substance magnets M placed in a combination of poles, as and magnetized, fix one of them, leave the other shown in the drawing around the periphery of holder free, and make the same poles face each other, as H which is made of non-magnetic material. Either shown in Fig. 1. One of the rings should float by an even or odd number of horse-shoe type magnets magnetic force. Actually, the upper ring does not will do. float but is attracted to the inside of the lower ring Fig. 5 shows the horse-shoe type of magnet as shown in Fig. 2. In this case, the inner ring is changed to an arc plate type. The change makes attracted to the inside of the outer ring and biased, it possible to form one solid ring and polarize it later, instead of being kept in the center. instead of having individual magnets.
Fig. 2
Fig. 1
Fig. 3 Fig. 4 Fig. 5 24
Fig. 6 shows the inner ring having poles in a yarn passes through the point of contact of the inner vertical direction being held. Fig. 7 shows the and outher rings. Whatever type of magnetic ring yoke attached to the magnet shown in Fig. 6 in is used must withstand these two kinds of force. order to strengthen the magnetic force in an inward Assume that inner ring R is in contact with direction. holder H at point A in Fig. 8. Then, point B of These examples give a basic idea of the method ring R (the magnetic force is weakest on the opposite of using the magnet ; all the examples can be put side to A) needs magnetic force Tz to resist the to practical use. the tension of the yarn. At the same time, hori
zontal attraction force TA should be below a certain limit so as to allow the yarn to make its way though
contact point A. The characteristic of the magnetic
ring can be found by measuring forces Tz and TA.
Composite vector T,,z indicates the suitability or otherwise of the magnetic ring.
Assuming that Tl represents permissible spinning
tension, it has to be Tz•†Tl. Assuming that T2 represents the acceptable contact force of point A,
then it has to be TA•…T2. Therefore, a magnetic
ring cannot be said to be suitable unless vector TAZ
comes within the area shown in the shadow line.
The characteristic of a magnetic ring of each type measured by the foregoing method is shown
in vector TAZ in Fig. 9. This figure gives the Fig. 6 Fig. 7 condition necessary for running worsted yarn of 2/48
at a spindle speed of 10,000 rev/min. The suitability One objection to these magnetic rings is that of a ring can be judged by whether its characteristic they have to be installed in individual machines and is within the area of the shadow line. tried before the degree of their suitability for spinning (2)in this figure is an example of the character can be determined. Therefore, it is desirable that isitc value where both the inner ring and outer ring some characteristic value of them be sought and are magnetized. ?? is an example of the chara used as a bias for judging their suitability. cteristic value where the periphery is magnetized. In both cases, vector TAZ is in an unqualified area
because the inner ring is held very strongly (Tz>
Forces on Inner Ring T1) and the horizontal constant force of inner ring
is too strong (TA>T2).
The inner ring is pulled upward by the tension of the yarn during spinning. The inner ring must, therefore, be held by a magnetic force which can withstand the tension and which, however, can resist the frictional force to be received when the revolving
Fig. 8 Fig. 9 25
Examples ?? and 6 are in the suitable area and yarn tension to a minimum. Fig. 10 shows yarn can be put to practical use. tension measured during operations by using a ring Example ?? shows the inner ring made to float selected from among the examples shown in Fig. 9 by the repulsive force of both magnetized rings. and considered suitable for the measurement. Though TA>T2, it is not suitable to a spindle speed This figure shows an experimental value under of 10,000 rev/min because TZ Fig. 10 Relation between the yarn tension and spindle speed Fig. 11 Where yarn package is large 26 limited by balloon tension and balloon size. (However in actual operations, it varies largely with traveller durability, the ends down of yarn and the quality of yarn.) The balloon size at less than 10,000 rev/min, in which air drag and delivery of the yarn may be neglected, is obtainable from this formula : b maximum balloon diameter (cm) r : diameter of inner ring (cm) n : number of revolutions of yarn (?? Spindle rev/min) Fig. 12 Relation between yarn number and spindle speed l : balloon stretch (cm) Tz : vertical component of balloon tension on the inner ring edge (g) Nm : metric number of worsted yarn Fig. 12 shows a curve obtained from an exper _??_ Aware of the proper value of ??TTNm from actual imental value and which indicates the spinning speed operations of traveller ring frames, we can get from at which today's magnetic rings can be run. Note carefully that there is a difference in the manner of the above formula the relationship between balloon size and spindle speed. Fig. 13 shows the re curving between the magnetic ring speed curve and lationship between r/b and n for 1=28cm and 1= the traveller ring speed curve. Theoretically, the 21cm. The value of r/b is limited by the spindle traveller ring should have the same trend as CC' which is the curve of the magnetic ring. The pitch of the machine to r/b=0.72 if no control ring is used for the balloon. Therefore, the spindle reason why it does not in operations is that the speed in that case is 7,700 rev/min. traveller, lacking in durability, is used in a way The spindle speed can be increased to r/b=0.5 which does not square with theory. if the balloon is controlled by an antinode ring. It How to adjust yarn tension is shown in Figs. 10 can, therefore, be raised to 8,600.11,500 rev/min. and 11. The spindle speed range is 12,000•`12,500 rev/min and the range of permissible spinning tension This almost agrees with the spindle speed we have T1 for both thick yarn of 2/36 and thin yarn of 2/60 obtained actually in a previous chapter. is 30•`60g. Accordingly, a speed of say, 10,000 rev/min., needs no adjustment of tension for 2/36 •` 2/60 (1/36•`1/60). This is a major advantage over the conventional traveller ring, with which the coarser the yarn, the lower the spindle speed. A magnetic ring needs no frequent changes of the traveller or spindle speed and is, therefore, a boon to worsted spinners who have to manufacture melange yarn in small lots. Theoretical Considerations The spindle speed which a magnet ring can give has been experimentally obtained in an earlier chapter. In what follows we shall investigate whether that spindle speed is reasonable compared with speed theoretically obtainable. Fig. 13 Spindle speed when balloon size is constant. Generally, the spindle speed of a ring frame is (for worsted yarn) 27 Next, the dynamic relationship of tension on the pulls the inner ring up at the start and thus precludes inner ring is regarded as almost the same as in cap operations. spinning. The coef- ficient of friction of the yarn is obtainable from this relationship. Assuming that the denotation is as shown in Fig. 14, then: ƒÊ : coefficient of tangential friction of the yarn on the inner ring edge. Fig. 15 36-spindle model frame using its travellerless ring ƒÊ0 : coefficient of yarn friction in the winding spinning device which is demonstrated at Nakayama mill direction on the inner ring edge. of Japan Wool Textile Co., Ltd., K : T/To Table 1 Various numerical values obtained from the pho tographed balloon size Table 2 A calculation applying (Table 1) numerical values to theoretical formula Fig. 14 _??_ A photograph of a service magnetic ring is shown in Fig. 15. Various numerical values obtained from Quality of Yarns Produced : the photographed balloon size are: A calculation applying these numerical values The upper part above the inner ring is the same to the theoretical formula gives the following results: both in the magnetic ring and the conventional travel Note that value ƒÊ in the above data is more ler ring. Therefore, the yarn remains the same in than twice as large as that of the traveller ring. quality while it is in that part. The absence of a This is the same for a cap frame. The largeness traveller in the magnetic ring influences the quality of value ƒÊ is a formidable obstacle to putting the of the yarn almost the same as a cap frame does magnetic ring practical use. This is because, if it produces slight fuzziness. However, the the friction between the yarn and the inner ring is magnetic ring can be improved further to eliminate large, it prevents smooth revolutions of the yarn, fuzziness. 28 Part 2 : Basic Experiment on Magnetization The magnetic ring being a new invention, manu Table 1 facturing data on it remain to be obtained. This report deals with an experiment made to get the minimum magnetic force required to withstand spinning tension in order to float the inner ring in the magnetic field in the air. It is a matter of course that the magnetic ring can not be a success Note : Expected spindle speed 6,800 r.p.m. if various ferro-magnetic substances cannot satisfy Weight of inner ring: 20g the requirement of the magnitude of said magnetic Magnetized with 4-poles around the circumference force. Table 2 Observing the Magnetic Force of the Ring The author made a few magnetic rings using a Note : Expected spindle speed 7,500 r.p.m. ferro-magnetic substance available at hand and in Weight of inner ring 20g stalled them in a spinning frame to see if they would Magnetized with 6-poles around the circumferences work. Some did not. Some did-only in low speed operations. After some renovations , however, all worked precisely at a speed of 10,000 rev/min . This graph shows the maximum pulling force The results of measuring the magnetic flux density of the inner ring. However, what is needed in of these experimental rings shown in Tables 1 and 2. practice is pulling force for the distance (2-3mm) The position where the magnetic flux was measured over which the inner ring is held up during spinning. is the one shown in Fig. 1. It was the inter Figs. 2 and 3 show also the relationship between the weight of the inner ring and pulling force. mediary position between the pole and pole , 0mm, 5 mm and 10mm toward the center; it was measured The reason why the author sought this this relation with a fluxmeter. ship was that he thought the weight of the inner Table 1 relates to 4-pole magnetization , Table 2 ring would be useful for supplementing the inadequacy to 6-pole magnetization. The mean flux density of the magnetic force. The experiment above of 4-poles is larger, but it cannot be judged merely mentioned has shown that the weight of a 15g by flux density whether 4-pole or 6-pole magneti inner ring will do for weaving worsted yarn. zation is better. At any rate, it has been established that the necessary flux density is 600-700 gauss . However, the magnetic force as it is cannot be regarded as the supporting force for the inner ring , because the magnetic force varies as the inner ring is magnetized when put into the magnetic field. The results of measuring the force which oper ates on the inner ring directly, instead of by obtaining the magnetic force, are shown in Figs. 2 and 3. Fig. 2 Magnetized with Fig. 3 Magnetized with Fig. 1 Measuring point of magnetic field 6 poles 4 poles 29 Pulling Force Acting upon the Inner Ring horizontally. The results of measuring the pulling force at a point on the periphery while the inner The condition of an inner ring receiving spin ring is held in the magnetic field as shown in Fig. 4, ning tension is such that a point on the periphery are given in Fig. 5. A shows the pulling force receives force. This point shifts along the peri of the position in which the inner ring is in contact phery at high speed and holds up the entire ring with the holder. B shows the pulling force on the opposite side. The difference between force A and force B indicates the variation of magnitude of the gaps of the ring or the irregularity of the magnetic force. It is desirable that curves A and B be close to each other. Thus the yarn operates on one point of the inner ring, but the inner ring floats horizontally because the operating point revolves at high speed. At this time inner ring, of course, makes whirling motions in the inner ring axis around the spindle shaft in the third dimension. The distance over which the inner ring floats must not exceed 3mm. Now, the pulling force obtained from Fig. 5, when the inner ring floats over a 3-mm distance, is shown in Fig. 4 Measuring point of pull force Table 3. Fig. 5 Upward pull force on inner ring edge. 30 Table 3 imentto be 0.36. When R and To are eliminated from the aforementioned enuations. _??_ With ƒÕ=38ß tan ƒ¿=0.36 k=0.788 substituted in the above equation, the following quadratic equation is obtained : It is desirable that the force of contact of the _??_ From the foregoing we obtain TA=1.523Tz. inner ring and the holder at point A be of maximum Instead of measuring adhesive force TA from this, weakness and that the pulling force at point B be it will do to measure force Tx which is needed for of maximum strength possible. Holder No. 4 in the yarn to pass through the gap. the foregoing table is, therefore, the best. Adhesive Force Acting upon the Point of Contact of Inner Ring and Magnetic Holder Fig. 6 Forces acting on inner ring at contact point A Fig. 6 shows the spinning conditon in which a Fig. 7 Measuring apparatus for adhesive force of inner magnetic ring is taken out and the yarn is hooked ring on it. r is the inner ring in contact with holder h Fig. 7 shows the measuring apparatus designed at point A. TA is the adhesive force of the inner by the author for T.. Drum B, which is slightly ring, it being assumed that the yarn is pinched at larger in diameter than the inner ring, and spring point A and that the force is balanced. Tx is balance C are fixed to frame A as shown in the assumed to be the component force with which the drawing. Band D is wound more than once on yarn is pulled in a vertical direction. To is assumed drum B and the band's end is fixed to the other to be the component force with which the yarn is reeled onto the bobbin, and R the reactive force point. Clip E at the lower end of the spring balance C is so arranged that-the ends of the yarn operating on the lower side of the inner ring. On reeled on the bobbin is pulled out and held in place these assumptions the following equilibrium of forces by it. is obtainable:_??_ When force A is pulled up along the arrow mark, drum B is revolved by band D. At the same time, the yarn is unwound from the bobbin while pulling spring C, and recording pen draws the curve on the chart. Tx of various magnetic tan a is the coefficient of friction between the rings measured by the method are shown in Fig. 8. yarn and the inner ring and was shown by exper The graph is the view from the rear of the chart. 31 Table 4 Relationship Between Good or Bad Magnetic Holder and Inner Ring As a result of measuring the adhesive force of the inner ring, the difference in characteristics between an operable magnetic ring and an inope rable magnetic ring has been made known. On the other hand, from this experiment it has also been made clear that even a slight error in processing The adhesive force TA obtained from this curve by the inner ring causes variations in magnetic force. the aforementioned formula is shown in Table 4. Fig. 9 shows the curve of unwinding tension where The abscissa in Fig. 8 shows the yarn length inner rings slightly differing in size and weight, as receiving tension and unwound from the bobbin. shown in Table 5, are combined with the same good This length, too, had better beshort. The form of holder. the curve has a bearing merely on the magnitude of the adhesive force of the inner ring in case holder No. 1 rises smoothly. Where, however, there is a concave in the curve, as in the curve for No. 117, it means that there are two contact points of the inner ring, and also that the inner ring vibrates and cannot be safely worked. A curve like the one for No. 115 has too large adhesive force. Because of this and the presence of two contact points, the magnetic ring represented by such a curve cannot be said to be adequate. Thus, the form of the curve which indicates unwinding tension represents and important characteristic by which the adequacy of the magnetic ring is judged. Fig. 9 Adhesive force of different inner ring when using the same holder Table 5 Fig. 8 Adhesive force of different inner ring and holder * Diameter is measured with micrometer 32 Observing the form of the curve shown in Fig. rings weighing 20g. This is presumably because 9, we note that ring F is the best. Rings B and of saturation magnetization in the strong magnetic E are about equal in tension to ring F but are not field. Ring F, when combined with this good adquate because there is a concave in the curve. The holder, can be worked at a spindle speed of 10,000 reason why these concaves developed in the un rev/min. Rings of the other kinds are operable winding tension curve even though the magnetic at a speed up to 8,000 rev/min. holder is good was that the inner ring was irregularly As shown in Fig. 8, there are no individual cut. magnetic rings which are inoperable. Note, however , Ring No. 14, though light in weight, is only even a very slight difference in the form and quality slightly different in adhesive force from the other of the inner ring affects high spindle speed.