A cone of an elastic yarn and a method for producing the same

Abstract

 The present invention relates to a cone of an elastic yarn, which has a superior form and is excellent in unwinding the elastic yarn from the cone.
In winding the elastic yarn on a tapered bobbin, a position of traverse support guide is moved so that a ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of said tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of said tapered bobbin and a ratio (L₂ / L₁) of a linear distance (L₂) between the traverse support guide and the larger end face of a cone of said tapered bobbin to a linear distance (L₁) between the traverse support guide and the smaller end face of a cone of the tapered bobbin becomes nearly equal. An average value of unwinding resistances of the elastic yarn from the cone of elastic yarn obtained is in a range of 3.2g to 3.4g.

Description

BACKGROUND OF THE INVENTION

Technical Field

[0001] The present invention relates to a method for winding an elastic yarn on a tapered bobbin in a favorable corn-like form. A cone of an elastic yarn obtained has a superior unwinding character, and can provide a wound yarn body of an elastic yarn having a form of corn suitable for supplying a yarn that is used in production field for industrial materials such as paper diaper and production fields for warp knitting and warping.

Prior Art

[0002] A wound yarn body having a corn form obtainable by winding a yarn on a tapered bobbin with the yarn being traversed, is widely applied in winding of an usual spun yarn and a synthetic fiber yarn such as polyester and nylon, because it has a superior unwinding character when a yarn is taken out along the direction of an end face of cone from a fixed cone. However, since winding velocity of a bobbin is different between a larger diameter side and a smaller diameter side when the yarn is wound in a cone form, a tension of winding becomes higher at a larger diameter side of the bobbin where a winding velocity is higher, and a tension of winding becomes lower at a smaller diameter side of the bobbin where a winding velocity is lower. Thus, there is a problem that a difference in tension of winding is generated between a larger diameter side and a smaller diameter side. This problem does not cause a practically serious obstacle with yarns having a low elongation which are conventionally used as stated above, but with yarns having a high elongation and low stress such as an elastic yarn of a bare polyurethane, winding on a tapered bobbin has not been employed because wound form becomes unfavorable due to the difference in tension of winding generated in winding on a tapered bobbin.

[0003] With regard to an elastic yarn, a cone of an elastic yarn for a paper diaper, which has a superior wound form and unwinding character with a winding amount of not lower than 1.5 kg and a value of (winding thickness) / (winding width) of not lower than 0.4, is known (see Patent reference 1). Said cone is suitable for unwinding the elastic yarn while the cone is revolved, but has a drawback, that is, a problem that the elastic yarn is caught by a lug of the cone resulting in a yarn breakage and the like, when the elastic yarn is unwound along the direction of an end face of the cone from the fixed cone. To improve such a drawback of the cone as described above, a cone of an elastic yarn which has a value of (winding thickness) / (winding width) of lower than 0.4 using an elastic yarn comprising a dry spun polyurethane-urea is also known (see Patent reference 2). However, each of these inventions relates to a parallel cheese as a fundamental form thereof, and when an elastic yarn is unwound along the direction of an end face of the cone from the fixed cone, an unwinding resistance is larger compared with that from a cone cheese, in particular, in the case of an elastic yarn of a bare polyurethane and the like, the large unwinding resistance causes problems such as yarn breakage and irregular feed tension.

Patent reference 1: JP-B-5-50429

Patent reference 2: JP-A-11-157750

DISCLOSURE OF THE INVENTION

[0004] An object of the present invention is to provide a method for producing a cone of an elastic yarn, wherein an irregular tension in winding, that is, a difference of tension for winding between a larger diameter side and a smaller diameter side in a direction of width of a tapered bobbin generated in winding an elastic yarn having a high elongation and a low stress on a tapered bobbin, has been solved, in order to obtain a cone of an elastic yarn having a superior form and an unwinding character without exhibiting unfavorable winding of a cone.

[0005] The inventors of the present invention intensively studied to solve the above-described problem paying attention on adjusting a position of traverse support guide, and thus accomplished the present invention.

[0006] Namely, the present invention provides a cone of an elastic yarn obtainable by winding an elastic yarn on a tapered bobbin with the yarn being traversed, wherein an average value of unwinding resistance of an elastic yarn from said cone of an elastic yarn is in a range of 3.2 to 3.4 g. In the present invention, an elastic yarn is wound on a tapered bobbin with the elastic yarn being traversed to produce a cone of an elastic yarn, wherein a position of traverse support guide is moved so that a ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of the tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of the tapered bobbin and a ratio (L₂ / L₁) of a linear distance (L₂) between a traverse support guide and a larger end face of a cone of the tapered bobbin to a linear distance (L₁) between a traverse support guide and a smaller end face of a cone of the tapered bobbin become nearly equal.

[0007] Here, it is preferable that the ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of the tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of the tapered bobbin and the ratio (L₂ / L₁) of a linear distance (L₂) between a traverse support guide and a larger end face of a cone of the tapered bobbin to a linear distance (L₁) between a traverse support guide and a smaller end face of a cone of the tapered bobbin, satisfies the following relation:

0.85 ≦ V₁L₁ / V₂L₂ ≦ 1.15.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] 

Fig. 1 is a conceptual drawing of a bobbin driven type of winding machine equipped with a detection sensor and a control equipment to wind an elastic yarn on a tapered bobbin.

Fig. 2 is an explanatory drawing to illustrate positional relations and linear distances between each part of a tapered bobbin and a traverse support guide.

Fig. 3 is a graph showing a correlation when a linear distance between a larger end face of the tapered bobbin and a traverse support guide is continuously adjusted in accordance with a change of a yarn layer thickness of the cone of an elastic yarn.

Fig. 4 is a graph showing a correlation when a linear distance between a larger end face of the tapered bobbin and a traverse support guide is intermittently adjusted in accordance with a change of a yarn layer thickness of the cone of an elastic yarn.

Fig. 5 is an explanatory drawing to illustrate positional relations of a cone of an elastic yarn, a plate-like yarn guide, an apparatus for measuring unwinding resistance (a tension meter), and a draw roller when the cone of an elastic yarn is unwound.

Fig. 6 is an explanatory drawing to illustrate a state of ballooning in the vicinity of a yarn layer thickness of 0.08 m when a wound body of an elastic yarn having a form of a parallel cheese is unwound.

Fig. 7 is an explanatory drawing to illustrate a state of ballooning in the vicinity of a yarn layer thickness of 0.04 m when a wound body of an elastic yarn having a form of a parallel cheese is unwound.

BEST MODE FOR CARRYING OUT THE INVENTION

[0009] Elastic yarn used in the present invention includes a polyurethane type of elastic yarn, a polyether type of elastic yarn, a polyester type of elastic yarn, a polyether-ester type of elastic yarn, a polyamide type of elastic yarn, a polycarbonate type of elastic yarn, a polybutylene terephthalate type of elastic yarn, and an elastic yarn obtainable by conjugating at least one of these elastic yarns and other materials. In particular, the effect of the present invention is remarkably exhibited when a bare polyurethane type of elastic yarn is used, which has a high elongation and a low stress and tends to easily tangle each other due to a large coefficient of friction of yarn surface. The elastic yarn may be either of a monofilament or a multifilament, but a multifilament is preferable in the present invention. Further, the elastic yarn may be adhered with a surface treatment agent such as a lubricant, or may be a bare elastic yarn. With regard to fineness thereof, an elastic yarn having such a wide range as 70 to 1,200 denier can be used.

[0010] Wound yarn body of an elastic yarn with a cone form, to which the present invention relates, may be either of a usual cone form wherein winding is performed with almost the same width from the beginning to the end of winding and a so-called pineapple form wherein a winding width becomes gradually narrower as winding progresses from the beginning to the end thereof. Taper angle of a tapered bobbin used in the present invention may be, for example, in a range of 3°30' to 9°15' as usually used.

[0011] Cone of an elastic yarn of the present invention is produced according to the method described below, and a cone of an elastic yarn obtained has a specified value of unwinding resistance. Namely, an average value of the unwinding resistance is preferably 3.2g to 3.4 g. In particular, in a case of a bare polyurethane elastic yarn, a value less than 3.2 g tends to cause unwinding by inertia due to a too small unwinding resistance, resulting in problems such as entanglement of the yarn. Contrary, a value over 3.4 g tends to cause yarn breakage or hinder smooth supply of the yarn.

[0012] Further, a deviation of unwinding resistance represented by the equation shown below is preferably 0.16 or less. A deviation over 0.16 is not preferable because a length of unwound elastic yarn is not stabilized due to a large dispersion of unwinding resistance, and for example, when an elastic yarn is used on a paper diaper manufacturing machine or a warp knitting machine, poor quality of a paper diaper or a warp knitting fabric produced may be resulted.

[0013] Unwinding resistance of an elastic yarn of the corn is measured using a unwinding resistance measuring equipment. For example, as described in Examples hereinbelow, an unwinding resistance is obtained by holding horizontally a corn of elastic yarn 11 rewound on a tapered bobbin, taking up the yarn at a velocity of 150 m/min through a plate-like yarn guide 12 equipped at the position apart by 0.46m from the rear end of the bobbin by a pair of rollers 13, 13 equipped at the position apart by 0.23m from said plate-like yarn guide 12, and measuring a tension of the elastic yarn by a tension meter 14 [model: PLS-0.2KC, made by NIDEC-SHIMPO CORPORATION] equipped at the position apart by 0.11m from said plate-like yarn guide 12.

[0014] Winding machine of a bobbin driven type, which is used for winding an elastic yarn on a tapered bobbin in the present invention, is composed of a commonly used winding machine equipped with detection sensors and a control equipment, and main parts thereof are shown in Fig. 1.

[0015] The winding machine used in the present invention may be used for direct winding of a spun elastic yarn, but is suitable for preferably rewinding from a wound body of an elastic yarn in a form of parallel cheese wound by the usual method. As a tapered bobbin, for example, bobbin 6 having a taper angle of 3°30' or the like is used, and said tapered bobbin 6 is mounted to spindle 7.

[0016] The spindle 7 is driven by an inverter motor via a gear device, and preferably has an equipment by which winding velocity is controlled to be constant even when yarn layer thickness 5 of a cone of an elastic yarn wound on the tapered bobbin 6 is increased. It is checked by detection sensor for number of revolution of touch roller 3 whether the predetermined winding velocity is maintained or not, using a control equipment having an arithmetic section where calculation is performed based on information obtained from detection sensor for yarn layer thickness 1, detection sensor for number of revolution of spindle 2, and detection sensor for number of revolution of touch roller 3, and an output section from which a signal for maintaining a predetermined winding velocity is sent.

[0017] The cone of an elastic yarn to be supplied for rewinding is fixed by a supporting means which is not shown in the figure, and elastic yarn 10, via guides such as a snail wire, is wound on the tapered bobbin 6 under a predetermined contacting pressure by touch roller 8 in contact with the tapered bobbin 6, while it is traversed with traversing device 9 through the traverse support guide a. In this connection, when the elastic yarn 10 is unwound from the cone of an elastic yarn to be supplied for rewinding, preferably a drive roller to positively deliver the yarn is used to reduce an influence of fluctuation of tension due to unwinding resistance.

[0018] As the traversing device 9 used in the present invention, a type using a traverse guide guiding an elastic yarn which make a reciprocating motion by a cam roller, or a type to traverse an elastic yarn using a rotating blade can be used. Traversing velocity is calculated by an arithmetic section based on information obtained from detection sensor for number of revolution of spindle 2 and detection sensor for traversing velocity 4, so as to maintain a winding number in a range of winding width from a position of beginning of winding at the larger diameter side of the cone and a position of beginning of winding at the smaller diameter side of the cone at a predetermined value, and a signal thereof is sent from the output section.

[0019] In the present invention, the detection sensor for yarn layer thickness 1 includes an ultrasonic sensor and a laser sensor, the detection sensor for number of revolution of spindle 2 includes a photo-sensor and a proximity sensor, the detection sensor for number of revolution of touch roller 3 includes a photo-sensor and a proximity sensor, and a detection sensor for traversing velocity 4 includes a photo-sensor. Each of these sensors used in the present invention can be appropriately selected from the above sensors, respectively.

[0020] Control equipment for a driven bobbin type of winding machine to wind an elastic yarn on the tapered bobbin 6 is composed of a setting section, an arithmetic section and an output section. The setting section may be composed of an input device such as a keyboard and a memory device for the input values. The data to be input include form-dependent values of the tapered bobbin used such as taper angle a, bobbin width F, a linear distance between the larger end face of bobbin and a position of beginning of winding at the larger diameter side of the cone of bobbin E, winding width D (see Fig. 2), and number of revolution of spindle and winding number in a range where the traverse guide traverses from a position of beginning of winding of the cone at the larger diameter side of bobbin to a position of beginning of winding of the cone at the smaller diameter side of bobbin, both of which are initially set values.

[0021] Further, the arithmetic section may be a section that can calculate (1) a position of the traverse support guide being traversed via a servomotor based on form-dependent values of the tapered bobbin, initially set values of the setting section and information from each detection sensor, (2) a number of revolution of the spindle to keep a winding velocity constant, and (3) a traversing velocity to keep a winding number in a range where the traverse guide traverses from a position of beginning of winding of the cone at the larger diameter side of bobbin to a position of beginning of winding of the cone at the smaller diameter side of bobbin, always constant. In addition, the output section may be a section that can output a signal for changing a number of revolution of the spindle, a traversing velocity, and a position of the traverse support guide a, based on results of the calculation performed by the arithmetic section based on form-dependent values of the tapered bobbin, initially set values of the setting section and information from each detection sensor.

[0022] In the present invention, a position of the traverse support guide a is determined by calculating so that a ratio of a winding velocity at the smaller end face of a cone of the tapered bobbin on which an elastic yarn is wound, to a winding velocity at the larger end face of a cone of the tapered bobbin, and a ratio of a linear distance between the traverse support guide a and the larger end face of a cone of the bobbin to a linear distance between the traverse support guide a and the smaller end face of a cone of the tapered bobbin becomes equal, and providing a direction to move a position of the traverse support guide a. Hereinafter, this will be explained by referring to Fig. 2. **Fig. 2 is an explanatory drawing to illustrate a positional relation of the cone of an elastic yarn wound on a tapered bobbin having taper angle a and the traverse support guide a, a positional relation of the center of a spindle and the traverse support guide a, a linear distance X between the traverse support guide a and the larger end face of the tapered bobbin, a linear distance L₂ between the traverse support guide a and the larger end face of cone of the tapered bobbin c, and a linear distance L₁ between the traverse support guide a and the smaller end face b of a cone of the tapered bobbin.

[0023] Winding velocity V₁ (m/sec) at the smaller end face of a cone of the tapered bobbin in the present invention is defined by the following equation (1) from diameter A (m) of the bobbin at a position of beginning of winding of a cone at the smaller diameter side of the tapered bobbin, yarn layer thickness G (m) of a corn, traversing velocity I (m/sec) and number of revolution of the spindle SP (number/sec).

[0024] Winding velocity V₂ (m/sec) at the larger end face of a cone of the tapered bobbin in the present invention is defined by the equation (2) shown below from diameter B (m) of the bobbin at a position of beginning of winding of a cone of the larger diameter side of the tapered bobbin, yarn layer thickness G (m) of a cone, traversing velocity I (m/sec) and number of revolution of the spindle SP (number/sec).

[0025] In addition, as stated in the present invention, a cone having a favorable form and a superior unwinding character can be obtained by calculating a position of the traverse support guide a, number of revolution of the spindle SP and traversing velocity I so that a ratio (L₂ / L₁) of linear distance L₂ (m) between the traverse support guide a and the larger end face c of a cone of the tapered bobbin to linear distance L₁ (m) between the traverse support guide a and the smaller end face b of a cone of the tapered bobbin becomes equal to a ratio (V₁ / V₂) of winding velocity V₁ (m/sec) at the smaller end face of a cone of the tapered bobbin, on which an elastic yarn is wound, to winding velocity V₂ (m/sec) at the larger end face of a cone of the tapered bobbin, that is, so as to satisfy the following equation (3), based on information obtained from detection sensor for yarn layer thickness 1, detection sensor for number of revolution of spindle 2, and detection sensor for traversing velocity 4 , and outputting the results to determine a position of the traverse support guide a.

Wherein,

V₁: winding velocity at the smaller end face of a cone of the tapered bobbin (m/sec);

V₂: winding velocity at the larger end face of a cone of the tapered bobbin (m/sec);

L₁: Linear distance (m) between the traverse support guide a and the smaller end face b of a cone of the bobbin; and

L₂: Linear distance (m) between the traverse support guide a and the larger end face c of a cone of the bobbin.

[0026] Here, the linear distance L₂ (m) between the traverse support guide a and the larger end face c of a cone of the bobbin is represented by the equation (4) below, provided that a linear distance between the larger end face C of the bobbin and the traverse support guide a is X (m), a linear distance between the larger end of the bobbin and a position of beginning of winding of a cone at the larger diameter side of the bobbin is E (m), a linear distance of the center of spindle and the traverse support guide a is H (m) , a diameter of the bobbin at the position of beginning of winding of a cone at the larger diameter side of the tapered bobbin is B (m), and a yarn layer thickness of the cone is G (m).

[0027] Further, a linear distance L₁ (m) between the traverse support guide a and the smaller end face b of a cone of the bobbin also is represented by the equation (5) below, provided that a winding width is D (m), a diameter of the bobbin at the position of beginning of winding of a cone at the smaller diameter side of the tapered bobbin is A (m).

[0028] Further, the distance from the center of spindle and the traverse support guide H (m) can be appropriately determined depending on a distance between each of bobbins mounted on a bobbin driven type of winding machine.

[0029] A position of the traverse support guide of the present invention is determined by the following procedures. First, a taper angle (a) which is a form-dependent value of the bobbin used, a width of the bobbin F (m), a distance between a larger end of the bobbin and a position of beginning ofwinding E (m), a wound width D (m), andanumber of revolution of a spindle SP₀ (number/see) and a winding number where a traverse guide transfers from a larger diameter side of the bobbin to that at a smaller diameter side thereof, both of which are initially setting values, are input. A diameter A (m) of the bobbin at the position of beginning of winding in a smaller diameter side of the bobbin, and a diameter B (m) of the bobbin at the position of beginning of winding in a larger diameter side of the bobbin, are calculated from the taper angle (a), the width of the bobbin F (m) , a distance between a larger end of the bobbin and a position of beginning of winding E (m), and a wound width D (m), which were input, and an initial velocity of traverse I₀ (m/sec) is calculated from an initial number of revolution of spindle SP₀ (number/see) and a winding number during the traverse guide travels from a larger diameter side of the bobbin to a smaller diameter side thereof. Next, supposing that a yarn layer thickness of a cone at the beginning of winding G₀ = 0 in the equations 1 and 2, a ratio (V₁ / V₂) of a winding velocity V₁ (m/sec) at a smaller end face of the tapered bobbin, to a winding velocity V₂ (m/sec) at a larger end face of the tapered bobbin, is calculated. Then, a position of the traverse support guide X₀ is calculated so that a ratio (L₂ / L₁) of a linear distance L₂ (m) between a traverse support guide a and a larger end face c of a cone of the bobbin to a linear distance L₁ (m) between a traverse support guide a and a smaller end face b of a cone of the bobbin becomes equal to the ratio (V₁ / V₂), namely L₂ / L₁ = V₁ / V₂, and is determined by selecting a positive value thereof.

[0030] In the equations 4 and 5, the diameter A (m) of the bobbin at the position of beginning of winding in a smaller diameter side thereof, and the diameter B (m) of the bobbin at the position of beginning of winding in a larger diameter side thereof, are values obtainable by the calculations as stated above, and a wound width D (m), a distance between a larger diameter of the tapered bobbin and a position of beginning of winding of the cone in a larger diameter side thereof E (m), and a linear distance of a spindle center and a traverse support guide H (m) are the values initially input. Therefore, a ratio (L₂ / L₁) of a linear distance L₂ (m) between a traverse support guide a and a larger end face c of the cone of a bobbin to a linear distance L₁ (m) between a traverse support guide a and a smaller end face b of the cone of a bobbin is a function of a yarn layer thickness of the cone G (m) and a linear distance between a larger end face of a bobbin and a traverse support guide X (m). Here, since the yarn layer thickness of the cone G (m) increases with time, L₂ / L₁ varies with a linear distance between a larger end face of a bobbin and a traverse support guide a X (m). L₂ / L₁ is determined by calculating V₁ / V₂ , and a corresponding linear distance between a larger end face of a bobbin and a traverse support guide X (m) becomes a solution of a quadratic equation, and the value thereof is essentially a positive one when a position of a traverse support guide at the beginning of winding is assumed to be X₀ (m). A taper angle of the tapered bobbin used, a diameter of the bobbin and a width of the bobbin, may be appropriately selected, so long as the position of a traverse support guide at the beginning of winding X₀ (m) is a positive value.

[0031] After the beginning of winding, a position of a traverse support guide X (m) and linear distance between a larger end face of a bobbin are determined in the same manner as of the procedures used for the beginning of winding except that values measured by each sensor are used as a yarn layer thickness of the cone G (m) , a traversing velocity I (m/sec) and a number of revolution of a spindle SP (number/sec). A position of a traverse support guide is preferably controlled continuously as shown in Fig. 3, but may be controlled stepwise in accordance with a yarn layer thickness of the cone as shown in Fig. 4 within a range not affecting winding form and unwinding character.

[0032] Namely, in the present invention, a position of a traverse support guide is controlled so that the relation of L₂ / L₁ = V₁ / V₂ is satisfied as described above, but the control may be performed continuously or stepwise within a certain range. Accordingly, in the present invention, the relation of L₂ / L₁ = V₁ / V₂ is not necessarily required to be satisfied, but the both values are required to be almost same, and for example, the values within the following range are acceptable. When a value of the ratio

is smaller than 0.85, namely, a tension of a smaller diameter side is smaller than that of a larger diameter side, loose winding or wrinkles occurs at an end face of the smaller diameter side, and bulge winding, cob-webbing and the like occurs at a larger end face. On the other hand, when a value of the ratio is larger than 1.15, namely, a tension of a smaller diameter side is larger than that of a larger diameter side, wavy edges or cob-webbing occurs at a smaller end face, and thus a wound package having a favorable corn form cannot be obtained.

[0033] Conventionally, when a yarn having a high elongation and a low stress such as a polyurethane elastic yarn was wound on a tapered bobbin, there was a remarkable influence due to a difference in winding tension between a larger diameter side and a smaller diameter side of the tapered bobbin, and if a winding tension at a smaller diameter side of the bobbin was kept properly, a winding tension at a larger diameter side of the bobbin became excessively large, resulting in a problem of unfavorable winding such as traversing-off often occurred. Contrary, if a winding tension at a larger diameter side of the bobbin was kept properly, a winding tension at a smaller diameter side of the bobbin became weak, resulting in a tendency of often occurrence of loose winding or wrinles. Such a phenomenon became more remarkable as a winding amount increased, or as a taper angle of the tapered bobbin increased. However, in the present invention, as stated above, by winding with a position of a traverse support guide being moved, a cone of a polyurethane elastic yarn having a favorable form and an excellent unwinding character can be obtained.

[0034] Winding amount of a cone of an elastic yarn obtained by the present invention is not particularly limited, and may be not only 500 g to 1.5 kg of an usual winding amount, but also a winding amount of a corn of not lower than the range. In particular, the method of the present invention is suitable for a winding amount of not lower than 1.0 kg, and can be suitably used in various fields.

EXAMPLES

[0035] Hereinbelow, the present invention will be explained in detail by referring to Examples, but is not construed to be limited to this scope. In the Examples, a winding tension of a cone of elastic yarn having a form of cone was evaluated by measuring a value of unwinding resistance during unwinding an elastic yarn from a cone of elastic yarn. Values of unwinding resistance in these Examples were measured by using an apparatus for measuring an unwinding resistance as described below, and a deviation of unwinding resistance (a dispersion of unwinding resistance values) was calculated from the measured values obtained.

Method for measuring by using an apparatus for measuring unwinding resistance and an equation for calculating a deviation

[0036] As shown in Fig. 5, unwinding resistance was obtained by holding horizontally a corn of elastic yarn 11 rewound on a tapered bobbin, taking up the yarn at a velocity of 150 m/min through a plate-like yarn guide 12 equipped at the position apart by 0.46m from the rear end of the bobbin by a pair of rollers 13, 13 equipped at the position apart by 0.23m from said plate-like yarn guide 12, and measuring a tension of the elastic yarn by a tension meter 14 [model: PLS-0.2KC, made by NIDEC SHIMPO CORPORATION] equipped at the position apart by 0.11m from said plate-like yarn guide 12 at 3 points of 40 mm, 20 mm and 5 mm in yarn layer thickness of a corn of elastic yarn for 30 sec. per each point. A deviation of unwinding resistance values was calculated from the maximum value, the minimum value and the average value of the unwinding resistance obtained by the following equation (6).

Example 1

[0037] Apolyurethane elastic yarn of 46.62 tex [Trade name: FUJIBO SPANDEX, manufactured by Fuji Spinning Co., Ltd.] having a weight of 3.0 kg, which was wound in a form of parallel cheese on a cylindrical bobbin and free of lubricant, was prepared. Then, as initially set values, a taper angle a = 3°30' which is a form-dependent value of the bobbin used, a smaller diameter of the bobbin = 0.047 m, a larger diameter C of the bobbin = 0.075 m, a width F of the bobbin = 0.2286 m, a linear distance E between a larger diameter end of a bobbin and a position of beginning of winding at a larger diameter side of a cone thereof = 0.015 m, a winding width D = 0.195 m, a linear distance H between a spindle center and a traverse support guide = 0.2 m, an initial number of revolution of a spindle SP₀ = 24.77 number/see, and a winding number during a period of the traverse guide moving from a larger diameter side of the bobbin to a smaller diameter side thereof = 3.25, were input. Arithmetic values of a diameter A of the bobbin at the position of beginning of winding of a cone of a smaller diameter side of the tapered bobbin = 0.0493 m, a diameter B of the bobbin at the position of beginning of winding of a cone of a larger diameter side of the tapered bobbin = 0.0732 m, and an initial traversing velocity I₀ = 1.49 m/sec, which were calculated from the initially set values input, were obtained. The arithmetic values obtained and an initial yarn layer thickness of a cone G₀ = 0 m, were substituted in said equations (1) and (2), and calculated to obtain the arithmetic values of the winding velocity V₁ at a smaller end face of the tapered bobbin 4.12 m/sec and the winding velocity V₂ at a larger end face of the tapered bobbin 5.88 m/sec.

[0038] Calculation was performed by substituting the arithmetic values of a ratio of velocities V₁ / V₂ = 0.70 obtained in said equations (4) and (5) to obtain a linear distance between a larger end face side of a bobbin and a traverse support guide of X₀ = 0.049 and -0.392. Adopting the positive value thereof, the traverse support guide was moved to a position of 0.049 m from a larger end face of a tapered bobbin by using a servomotor. Then, a number of revolution of a spindle was controlled to become an average speed 5.0 m/sec = 300 m / min of a winding velocity V₁ = 4.12 m/sec at a smaller end face of a cone of the tapered bobbin and a winding velocity V₂ = 5.88 m/sec at a larger end face of a cone of the tapered bobbin, and a traversing velocity was controlled to maintain a winding number 3.25 during a period of the traverse guide moving from a larger diameter side to a smaller diameter side, and further a position of the traverse support guide was controlled so that a ratio (L₂ / L₁) of a linear distance L₂ (m) between a traverse support guide, which varied with an increase of a yarn layer thickness of a cone, and a larger end face of a cone of the bobbin to a linear distance L₁ (m) between a traverse support guide and a smaller end face of a cone of the bobbin, became equal to a ratio (V₁ / V₂) of a winding velocity V₁ (m/sec) at a smaller end face of a cone of the tapered bobbin to a winding velocity V₂ (m/sec) at a larger end face of a cone of the tapered bobbin, to produce 3 kg of a cone of polyurethane elastic yarn having a corn form.

[0039] Results of appearance examination on a wound yarn body of polyurethane elastic yarn having a corn form, measurements of unwinding resistances at 40 mm, 20 mm, and 5 mm of yarn layer thickness, deviations of unwinding resistance, and examination on winding states of a polyurethane elastic yarn in the most inner layer within a yarn layer thickness of 2 mm, are shown in Table 1.

Table 1

Result of appearance examination	Winding form was cone-like and favorable without deformation.
Thickness of yarn layer (mm)	Unwinding resistance (g)			Deviation
	Maximum	Minimum	Average
40 mm	3.4	2.9	3.2	0.16
20 mm	3.5	3.0	3.3	0.15
5 mm	3.6	3.1	3.4	0.15
2 mm or less or less	Almost uniform tension was obtained without loosening of a polyurethane elastic yarn in the most inner layer.

[0040] From Table 1, it can be seen that average values of unwinding resistances are in a range of 3.2 to 3.4, though those at the beginning of winding tend to have slightly higher values, and a deviation thereof resides in a range of 0.15 to 0.16. Thus, a wound yarn body of polyurethane elastic yarn having a cone form and a superior unwinding character was obtained, and further both of end faces of a corn package were almost plane-like. Further, an appearance and a winding state in each yarn layer were also superior.

Comparative Example 1

[0041] Using the same polyurethane elastic yarn of 46.62 tex having a winding amount of 3 kg as in Example 1, and a tapered bobbin having the same form-dependent value as in Example 1, 3 kg of a cone of polyurethane elastic yarn having a corn form was produced at a winding velocity of 300 m/min by using a bobbin driven style of winding machine with a traverse support guide fixed at a position apart by 0.03 m from a larger end face of a tapered bobbin without moving.

[0042] In the same way as in Example 1, results of appearance examination on a wound yarn body of polyurethane elastic yarn having a corn form, measurements of unwinding resistances at 40 mm, 20 mm, and 5 mm of yarn layer thickness, deviations of unwinding resistance values, and examination on wound states of polyurethane elastic yarn within the most inner layer of 2 mm of yarn layer thickness, are shown in Table 2.

Table 2

Result of examination examination	Occurrences of bulge winding and wrinkles were observed.
Thickness of yarn layer (mm)	Unwinding resistance (g)			Deviation
	Maximum	Minimum	Average
40 mm	4.3	3.4	3.9	0.23
20 mm	4.3	3.4	4.1	0.22
5 mm	4.4	3.8	4.2	0.14
2 mm or less or less	Almost uniform tension was obtained without loosening of a polyurethane elastic yarn in the most inner layer.

[0043] From Table 2, it can be seen that average values of unwinding resistance are in a range of 3.9 to 4.2, and the value at the beginning of winding tend to show a higher value and gradually lower, but deviations of unwinding resistance are higher compared with those in Example 1. With regard to results of appearance examination, the appearance was poor with bulge winding having a wrinkles at the smaller end face of the bobbin, and thus a cone of a polyurethane elastic yarn having a favorable unwinding property could not be obtained.

Comparative Example 2

[0044] By the same way as in Comparative Example 1 except that a position of the traverse support guide was fixed at a position apart by 0.11 m from a larger end face of the tapered bobbin, 3 kg of a wound yarn body of polyurethane elastic yarn having a cone form was produced at a winding velocity of 300 m/min by using a bobbin driven type of winding machine.

[0045] Results of the appearance examination on the cone of polyurethane elastic yarn having a cone form obtained, the measurements of unwinding resistances at 40 mm, 20 mm and 5 mm in yarn layer thickness, the calculations of deviations of unwinding resistance, and the examination on wound states of a polyurethane elastic yarn within the most inner layer within 2 mm of yarn layer thickness, are shown in Table 3.

Table 3

Result of appearance examination	Wound form was favorable without deformation. deformation.
Thickness of yarn layer (mm)	Unwinding resistance (g)			Deviation
	Maximum	Minimum	Average
40 mm	4.0	3.5	3.7	0.14
20 mm	4.2	3.4	3.8	0.21
5 mm	4.3	3.4	3.8	0.24
2 mm or less	Loose winding of a polyurethane elastic yarn occurred in the most inner layer.

[0046] From Table 3, it can be seen that average values of unwinding resistance are in a range of 3.7 to 3.8 and almost in the same level, but deviations thereof are higher compared with those in Example 1. The result of appearance examination was favorable, but loose winding of a polyurethane elastic yarn was generated in the most inner layer, and therefore this was not a cone of polyurethane elastic yarn having a superior unwinding character.

Reference Example

[0047] Using a cone of a polyurethane elastic yarn of 44.62 tex and free of lubricant having a form of parallel cheese with a winding amount of 3.0 kg, which was used in Example 1, an unwinding resistance was measured by using an apparatus for measuring unwinding resistance as described in Example, and deviations were calculated from the results the measurements. Results are shown in Table 4. A cone of a polyurethane elastic yarn having a form of parallel cheese with a winding amount of 3 kg, was wound at a diameter of bobbin of 0.085 m, a width of the bobbin of 0.1143 m, a winding width of 0.096 m, and a yarn layer thickness of 0.095 m. Measurements of unwinding resistance were made at three points of 80 mm, 40 mm and 5mm.

Table 4

Thickness of yarn layer (mm)	Unwinding resistance (g)			Deviation
	Maximum	Minimum	Average
80 mm	9.8	2.8	4.2	1.67
40 mm	3.8	2.8	3.2	0.31
5 mm	3.5	2.9	3.1	0.19

[0048] From Table 4, it can be seen that average values of unwinding resistance are in a range of 3.1 to 4.2 and uneven, and deviations thereof are larger and in a range of 0.19 to 1.67. At a yarn layer thickness of 80mm, ballooning in unwinding is large as shown in Fig. 6. Although a ballooning state becomes moderate at a yarn layer thickness of 40 mm as shown in Fig. 7, but deviations of unwinding resistance were larger and fluctuation in tension was larger compared with those of the cone of a polyurethane elastic yarn of the present invention.

EFFECT OF THE INVENTION

[0049] A wound yarn body of a polyurethane elastic yarn having a corn form obtainable according to the method of the present invention does not exhibit an unfavorable form in appearance, nor loose winding in an inner layer of a cone, and exhibits a superior unwinding character with less variation of tension due to a small deviation of unwinding resistance, and thus has enabled to wind a bare polyurethane elastic yarn on a tapered bobbin.

INDUSTRIAL APPLICABILITY

[0050] The cone of a bare polyurethane elastic yarn having a corn form obtained by the present invention has a superior unwinding character, a small deviation of unwinding resistance and a small dispersion of tension, without exhibiting an unfavorable form in appearance and a loose batching in the most inner layer of a corn. Further, a winding amount of a package can be arbitrarily set, in particular, a cone having a larger winding amount than usual can be produced. Thus, the cone of the present invention can be suitably used in a production field for paper diaper and the like or a production fields for warp knitting and the like.

[0051] The term 'cheese' used in this specification refers to the wound yarn package formed by winding yarn onto a bobbin. The term 'parallel cheese' refers to a wound yarn package having a substantially cylindrical or tubular shape with substantially parallel sides. The term 'cone cheese' refers to a wound yarn package having a substantially frustoconical or tapered shape with converging sides.

Claims

1. A cone of an elastic yarn wound on a tapered bobbin with the elastic yarn being traversed, wherein an average value of unwinding resistance of said elastic yarn from said cone of an elastic yarn is in a range of 3.2g to 3.4g.

2. A cone of an elastic yarn according to Claim 1, wherein said elastic yarn is a bare polyurethane type of elastic yarn.

3. A cone of an elastic yarn according to Claim 1 or Claim 2, wherein, in winding said elastic yarn on a tapered bobbin with said elastic yarn being traversed, a position of traverse support guide is moved so that a ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of said tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of said tapered bobbin and a ratio (L₂ / L₁) of a linear distance (L₂) between the traverse support guide and the larger end face of a cone of said tapered bobbin to a linear distance (L₁) between the traverse support guide and the smaller end face of a cone of the tapered bobbin becomes nearly equal.

4. A cone of an elastic yarn according to Claim 3, wherein a ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of said tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of said tapered bobbin and a ratio (L₂ / L₁) of a linear distance (L₂) between the traverse support guide and the larger end face of a cone of said tapered bobbin to a linear distance (L₁) between the traverse support guide and the smaller end face of a cone of the tapered bobbin satisfy the relation of 0.85 ≦ V₁L₁ / V₂L₂ ≦ 1.15.

5. A method for producing a cone of an elastic yarn, wherein in winding said elastic yarn on a tapered bobbin with said elastic yarn being traversed, a position of traverse support guide is moved so that a ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of said tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of said tapered bobbin and a ratio (L₂ / L₁) of a linear distance (L₂) between the traverse support guide and the larger end face of a cone of said tapered bobbin to a linear distance (L₁) between the traverse support guide and the smaller end face of a cone of the tapered bobbin becomes nearly equal.

6. A method for producing a cone of an elastic yarn according to claim 5, wherein a ratio (V₁ / V₂) of winding velocity (V₁) at a smaller end face of a cone of said tapered bobbin to a winding velocity (V₂) at a larger end face of a cone of said tapered bobbin and a ratio (L₂ / L₁) of a linear distance (L₂) between the traverse support guide and the larger end face of a cone of said tapered bobbin to a linear distance (L₁) between the traverse support guide and the smaller end face of a cone of the tapered bobbin satisfy the relation of 0.85 ≦ V₁L₁ / V₂L₂ ≦ 1.15.

7. A cone of an elastic yarn produced by a method according to claim 5 or 6.

8. An apparatus for producing a cone of an elastic yarn by winding elastic yarn onto a tapered bobbin, comprising a traverse support guide for traversing said yarn, means for measuring the winding velocity (V₁) at the smaller end of the cone, means for measuring the winding velocity V₂ at the larger end of the cone, means for measuring the linear distance (L₁) between the traverse support guide and the larger end of the cone, means for measuring the linear distance (L₂) between the traverse support guide and the smaller end of the cone and means for adjusting the winding velocities V₁ and/or V₂ and/or the linear distances L, and/or L₂ so that the ratio V₁/V₂ is approximately equal to the ratio L₂/L₁.

9. An apparatus according to claim 8 wherein 0.85 ≤ V₁L₁/V₂L₂ ≤ 1.15.

Drawing