Thick and thin yarn manufacturing method

Abstract

To manufacture a thick and thin yarn by a simple method.SOLUTION: In a thick and thin yarn manufacturing method, variation in dyeability is applied to a false-twisted yarn Yf formed by false-twisting an original yarn Yr made of polyester-based synthetic fibers. In the manufacturing method, a third feed roller 18 and a fourth feed roller 20 feed the false-twisted yarn Yf to a downstream side in a yarn travelling direction and the false-twisted yarn Yf is heated by a second heating device 19 having a contact face 56. The heating temperature of the second heating device 19 is set so that the false-twisted yarn Yf is at least partially heated to a temperature equal to or higher than a predetermined temperature causing change in dyeability and heat shrinkage in the second heating device 19. the overfeed ratio is held at 15% or more. Consequently, the false-twisted yarn Yf travelling while being heat-shrunk is fed to the downstream side in the yarn travelling direction while being loosened.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a method for producing thick and thin yarn. [Background technology]

[0002] Patent Document 1 discloses a method for producing false twist textured yarn formed by false twisting a yarn made of polyester synthetic fiber. More specifically, in this production method, before the false twisting, a running highly oriented undrawn yarn is heated and drawn by contacting it with a hot pin. This intentionally produces drawing unevenness in the running yarn. When a cloth produced using false twist textured yarn formed from such a yarn is dyed with a heated dye, a heathered look (uneven dyeing) is imparted to the cloth. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-183732 A Summary of the Invention [Problem to be solved by the invention]

[0004] Hereinafter, for convenience of explanation, a yarn having variation in dyeability in the longitudinal direction and serving as a material for fabric having a heathered texture after dyeing will be referred to as a thick and thin yarn, regardless of the shape, structure, or raw material of the yarn. Although not described in Patent Document 1, in a method of drawing a running yarn (single yarn) while contacting it with the above-mentioned hot pin, a thick and thin yarn is produced as follows. That is, the known stick-slip phenomenon is intentionally generated by making the running speed of the yarn, the tension of the yarn, and the frictional force generated between the yarn and the hot pin satisfy specific conditions. As a result, the running speed of the yarn in contact with the hot pin is intentionally changed over time. As a result, in the yarn, a microcrystalline portion (thin portion) that is greatly drawn and oriented in the longitudinal direction of the yarn, and an amorphous portion (thick portion) that is not drawn as compared to the microcrystalline portion and maintains an amorphous state are alternately formed in the longitudinal direction. Dyes do not easily penetrate into the microcrystalline portions, and dyes penetrate relatively easily into the amorphous portions.

[0005] Here, in the method for producing thick and thin yarn using hot pins, there is a problem that the running speed of the yarn cannot be increased in order to prevent the yarn from being cut by rubbing against the hot pins.

[0006] An object of the present invention is to rapidly produce thick and thin yarns. [Means for solving the problem]

[0007] A method for producing a thick and thin yarn of a first invention is a method for producing a thick and thin yarn in which a variation in dyeability is imparted to the yarn in the longitudinal direction of the yarn, the yarn being a false twisted yarn formed by false twisting a raw yarn made of a polyester-based synthetic fiber, the false twisted yarn being fed downstream in the yarn running direction in which the false twisted yarn runs by a first yarn feeding device that feeds the false twisted yarn downstream in the yarn running direction in which the false twisted yarn runs, and a second yarn feeding device arranged downstream in the yarn running direction from the first yarn feeding device, the false twisted yarn being fed downstream in the yarn running direction, and the false twisted yarn being heated by a heating device arranged between the first yarn feeding device and the second yarn feeding device in the yarn running direction, The heating device has a heat source and a contact surface formed in a heating section heated by the heat source, arranged to extend along the yarn running direction, and arranged to come into contact with the false twist textured yarn.The heating temperature of the heating device is set so that the false twist textured yarn is at least partially heated in the heating device to a temperature equal to or higher than a predetermined temperature at which a change in dyeability and thermal shrinkage occurs, and an overfeed rate calculated based on a first yarn feeding speed by the first yarn feeding device and a second yarn feeding speed by the second yarn feeding device, which is slower than the first yarn feeding speed, is maintained at 15% or more, thereby relaxing the false twist textured yarn as it runs while thermally shrinking, and feeding it downstream in the yarn running direction.

[0008] Polyester synthetic fibers are a general term for synthetic fibers made of a material produced by dehydration condensation of polyalcohol and polycarboxylic acid. The thick and thin yarn of the present invention refers to a yarn that has variation in dyeability in the longitudinal direction and is used as a material for fabric with a heathered feel. Dyeability refers to the ease with which the yarn can be dyed with a dye. In the present invention, a false twist textured yarn that has already been false twisted is heated to a predetermined temperature or higher, causing a change in dyeability and allowing it to run while undergoing thermal shrinkage. The present inventor has found that a thick and thin yarn can be produced by feeding such a false twist textured yarn while relaxing it at a high overfeed rate of 15% or more. The present inventor considers the reason for this as follows. That is, a false twist textured yarn that runs while being largely relaxed runs in a slightly wavy manner, and in the longitudinal direction, it is divided into a portion that comes into contact with the contact surface and is heated thoroughly, and a portion that does not come into contact with the contact surface and is not heated much. The portion of the false twist textured yarn that comes into contact with the contact surface becomes hot, undergoes thermal shrinkage, and increases in thickness. Then, the thickened portion (hereinafter referred to as the first yarn portion) is more likely to come into contact with the contact surface. As a result, the temperature rises to a predetermined temperature or higher around the first yarn portion in the longitudinal direction, and thermal shrinkage (and changes in dyeability) progresses further. On the other hand, the portion (hereinafter referred to as the second yarn portion) that is not in contact with the contact surface as much as the first yarn portion is less likely to become hot, and the progress of thermal shrinkage is suppressed compared to the first yarn portion. Therefore, the thickness of the second yarn portion is less likely to increase, and thermal shrinkage (and changes in dyeability) is further suppressed compared to the first yarn portion. As a result, in the false twist textured yarn, portions where the dyeability changes significantly and portions where the change is relatively small can be formed alternately in the longitudinal direction. As described above, in the manufacturing method of the present invention, there is no need to use a hot pin, and the above-mentioned concerns about yarn breakage are avoided, so the yarn can be run at high speed. In addition, as described above, the yarn can be run at a high overfeed rate of 15% or more. Therefore, thick and thin yarn can be manufactured at high speed.

[0009] A second aspect of the present invention is a method for producing a thick and thin yarn according to the first aspect of the present invention, characterized in that the false twist textured yarn is made of a single yarn.

[0010] Generally, a method for producing a thick and thin yarn by false-twisting and doubling two yarns having different thermal shrinkage rates is also known. However, in order to adopt this method, a large-scale facility is required for false-twisting and doubling the two yarns, and two types of raw yarns with different characteristics must be prepared. In the present invention, a thick and thin yarn can be produced by simply heating a single false-twisted yarn while relaxing it. Therefore, a thick and thin yarn can be produced by a simple configuration and method.

[0011] The method for producing a thick and thin yarn of the third invention is characterized in that, in the second invention, the first yarn feeding speed and the second yarn feeding speed are 600 m / min or more.

[0012] The present invention allows for the production of thick and thin yarns at high speeds.

[0013] The manufacturing method of thick and thin yarn of the fourth invention is characterized in that, in any of the first to third inventions, the material of the false twist textured yarn changes its crystalline state when heated to or above the specified temperature, thereby changing the dyeability.

[0014] It is generally known that there exist polyester synthetic fiber materials whose dyeability changes depending on the crystal state. In the present invention, the dyeability of the false twist textured yarn can be intentionally varied in the longitudinal direction by a simple method in which the false twist textured yarn is heated and run at a predetermined overfeed rate.

[0015] A fifth invention relates to a method for producing a thick and thin yarn according to the fourth invention, and is characterized in that the predetermined temperature is the melting point of a material of the false twist textured yarn.

[0016] By heating the false twist textured yarn above the melting point of the material of the false twist textured yarn, the crystalline state of the material can be significantly changed.

[0017] The method for producing thick and thin yarn of the sixth invention is characterized in that, in the fifth invention, the melting point is 255° C. or higher.

[0018] The melting point of polyester-based synthetic fiber material is generally about 255° C. to 260° C. Alternatively, the melting point of the material may be higher than 260° C. In the present invention, the crystal state of the material can be significantly changed by heating the false twist textured yarn to such a high temperature.

[0019] The seventh invention relates to a method for producing thick and thin yarn according to the sixth invention, and is characterized in that in the heating device, the temperature setting value of the heating section is set to 350° C. or higher.

[0020] In the present invention, the temperature of the heating section is set to a high value of 350° C. or more, so that the false twist textured yarn is effectively heated. As a result, even if the running speed of the false twist textured yarn is fast, the false twist textured yarn can be heated to the required temperature. Therefore, thick and thin yarn can be produced at high speed.

[0021] The method for producing thick and thin yarn according to an eighth aspect of the present invention is characterized in that, in the seventh aspect of the present invention, the temperature of the heating section in the heating device is set to 400° C. or higher.

[0022] In the present invention, the temperature of the heating section is set to a high value of 400° C. or more, so that the false twist textured yarn is effectively heated. As a result, even if the false twist textured yarn runs fast or is thick and difficult to heat, the false twist textured yarn can be heated to the required temperature. Therefore, thick and thin yarn can be produced at high speed.

[0023] The method for producing a thick and thin yarn of the ninth invention is characterized in that, in the seventh or eighth invention, the false twist textured yarn has a thickness of 50 dtex or more.

[0024] In the present invention, it is possible to efficiently heat the false twist textured yarn, and therefore, even when using a false twist textured yarn that is thick and difficult to heat, the present invention makes it possible to produce a thick and thin yarn with stable quality.

[0025] The manufacturing method of thick and thin yarn of the 10th invention is characterized in that, in any of the first to ninth inventions, the raw yarn is false twisted upstream of the first yarn feeding device in the yarn running direction to form the false twist textured yarn, while the false twist textured yarn is run toward the first yarn feeding device.

[0026] In the present invention, while the false twist textured yarn is being formed, the formed false twist textured yarn can be used as is to produce a thick and thin yarn. In a production method such as that of the present invention, it is particularly effective to be able to produce a thick and thin yarn at high speed.

[0027] The manufacturing method of thick and thin yarn of the 11th invention is characterized in that, in any of the first to tenth inventions, the yarn path of the false twist textured yarn is set in advance so that the false twist textured yarn comes into contact with the contact surface when assuming that the false twist textured yarn is running without relaxation through the heating device.

[0028] In a method in which the false twist textured yarn is brought into contact with the contact surface only when the false twist textured yarn is running in a relaxed state, it is necessary to very slightly separate the yarn path from the contact surface when it is assumed that the false twist textured yarn is running in the heating device without being relaxed. This can make it very difficult to set an appropriate yarn path. In this regard, in the present invention, it is sufficient to set the yarn path so that the false twist textured yarn comes into contact with the contact surface when it is not relaxed. Therefore, an appropriate yarn path can be easily set. [Brief description of the drawings]

[0029] [Figure 1] 1 is a side view of a yarn processing machine for carrying out a method for manufacturing thick-and-thin yarn according to an embodiment of the present invention. FIG. [Diagram 2] FIG. 2 is a schematic diagram showing a yarn processing machine deployed along a yarn path. [Diagram 3] 6(a) to 6(c) are explanatory views showing a second heating device. [Figure 4] Photographs of fabrics made using yarns produced by the yarn processing machine. [Diagram 5] Photograph of fabric made using Thick and Thin yarn. [Figure 6] FIG. 1 is an explanatory diagram for considering the principle by which thick-and-thin yarn is formed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] Next, an embodiment of the present invention will be described. The direction perpendicular to the plane of the paper in Fig. 1 is the machine base longitudinal direction, and the left-right direction of the paper is the machine base width direction. The direction perpendicular to both the machine base longitudinal direction and the machine base width direction is the up-down direction (vertical direction) in which gravity acts. The machine base longitudinal direction and the machine base width direction are approximately parallel to the horizontal direction.

[0031] (Overall configuration of yarn processing machine) First, the overall configuration of a yarn processing machine 1 for carrying out the manufacturing method of thick-and-thin yarn of this embodiment will be described with reference to Fig. 1 and Fig. 2. Fig. 1 is a side view of the yarn processing machine 1. Fig. 2 is a schematic view of the yarn processing machine 1 developed along the path (yarn path) of the yarn Y. The direction in which the yarn travels is defined as the yarn travel direction.

[0032] The yarn processing machine 1 is configured to process a yarn Y made of a synthetic fiber (e.g., a polyester-based synthetic fiber). The processing in this embodiment includes the manufacture of a false twist textured yarn (i.e., false twist texture). The yarn Y is, for example, a multifilament yarn made of a plurality of filaments. Alternatively, the yarn Y may be made of a single filament. The yarn processing machine 1 includes a yarn supplying section 2, a processing section 3, and a winding section 4. The yarn supplying section 2 is configured to be able to supply the yarn Y. The processing section 3 is configured to pull out the yarn Y from the yarn supplying section 2 and process it. The winding section 4 is configured to wind the yarn Y processed by the processing section 3 onto a winding bobbin Bw. The components of the yarn supplying section 2, the processing section 3, and the winding section 4 are arranged in a plurality of rows in the machine frame longitudinal direction (see FIG. 2). The machine frame longitudinal direction is a direction perpendicular to the running plane of the yarn Y (the plane of the paper in FIG. 1) formed by the yarn path from the yarn supplying section 2 through the processing section 3 to the winding section 4.

[0033] The yarn supplying section 2 has a creel stand 7 that holds a plurality of yarn supply packages Ps, and supplies a plurality of yarns Y to the processing section 3. The processing section 3 is configured to pull out a plurality of yarns Y (raw yarns Yr) from the yarn supplying section 2 and process them. Each of the raw yarns Yr is a single yarn (i.e., one multifilament yarn or one monofilament yarn). The processing section 3 is configured to have, in order from the upstream side in the yarn running direction, a first feed roller 11, a twist stop guide 12, a first heating device 13, a cooling device 14, a false twist device 15, a second feed roller 16, an intertwining device 17, a third feed roller 18 (a first yarn feeding device of the present invention), a second heating device 19 (a heating device of the present invention), and a fourth feed roller 20 (a second yarn feeding device of the present invention). The winding section 4 has a plurality of winding devices 21. Each winding device 21 winds the yarn Y that has been false twisted in the processing section 3 onto a winding bobbin Bw to form a winding package Pw.

[0034] The yarn processing machine 1 has a main machine base 8 and a winding table 9 arranged at an interval in the width direction of the machine base. The main machine base 8 and the winding table 9 are provided so as to extend to approximately the same length in the longitudinal direction of the machine base. The main machine base 8 and the winding table 9 are arranged so as to face each other in the width direction of the machine base. The yarn processing machine 1 has a unit called a span, which includes one set of the main machine base 8 and the winding table 9. In one span, each device is arranged so that multiple yarns Y running in a line in the longitudinal direction of the machine base can be false twisted simultaneously. In the yarn processing machine 1, this span is arranged symmetrically on the left and right of the drawing with the center line C in the width direction of the main machine base 8 as the axis of symmetry (the main machine base 8 is common to the left and right spans). In addition, multiple spans are arranged in the longitudinal direction of the machine base.

[0035] (Configuration of processing part) The configuration of the processing unit 3 will be described with reference to Figs. 1 and 2. The first feed roller 11 is configured to unwind the yarn Y from the yarn supplying package Ps attached to the yarn supplying unit 2 and send it to the first heating device 13. For example, as shown in Fig. 2, the first feed roller 11 is configured to send one yarn Y to the first heating device 13. Alternatively, the first feed roller 11 may be configured to be able to send each of adjacent yarns Y downstream in the yarn running direction. The twist stop guide 12 is configured to prevent the twist imparted to the yarn Y by the false twist device 15 from propagating upstream of the twist stop guide 12 in the yarn running direction.

[0036] The first heating device 13 is a device for heating the yarn Y sent from the first feed roller 11 to a predetermined processing temperature. The first heating device 13 is, for example, a non-contact heating device described in JP 2002-146640 A. The first heating device 13 is configured to be capable of heating one yarn Y, for example, as shown in FIG. 2. Alternatively, the first heating device 13 may be configured to be capable of simultaneously heating a plurality of yarns Y. The heating temperature of the first heating device 13 (the set temperature of a heat source, not shown) can be raised to a high temperature of about 550° C. The cooling device 14 is configured to cool the yarn Y heated by the first heating device 13. The cooling device 14 is configured to cool one yarn Y, for example, as shown in FIG. 2. Alternatively, the cooling device 14 may be configured to cool a plurality of yarns Y simultaneously.

[0037] The false twist device 15 is disposed downstream of the cooling device 14 in the yarn running direction and configured to impart a twist to the yarn Y. The false twist device 15 is, for example, a so-called disk friction type false twist device, but is not limited thereto. The second feed roller 16 is configured to send the yarn Y processed by the false twist device 15 to the intertwining device 17. The conveying speed of the yarn Y by the second feed roller 16 is faster than the conveying speed of the yarn Y by the first feed roller 11. As a result, the yarn Y is stretch-twisted between the first feed roller 11 and the second feed roller 16. The intertwining device 17 is configured to impart intertwining to the yarn Y. The intertwining device 17 has, for example, a known interlace nozzle that imparts intertwining to the yarn Y by air flow.

[0038] The third feed roller 18 is configured to send the yarn Y traveling downstream of the intertwining device 17 in the yarn traveling direction to the second heating device 19. The third feed roller 18 is configured to send one yarn Y to the second heating device 19, for example, as shown in FIG. 2. Alternatively, the third feed roller 18 may be configured to send adjacent yarns Y to the downstream side in the yarn traveling direction. The conveying speed of the yarn Y by the third feed roller 18 is slower than the conveying speed of the yarn Y by the second feed roller 16. Therefore, the yarn Y is relaxed between the second feed roller 16 and the third feed roller 18. More specifically, the conveying speed of the yarn Y by the third feed roller 18 is slower than the conveying speed of the yarn Y by the second feed roller 16 by, for example, about 2.5% to 5%. However, the difference in conveying speed is not limited to this.

[0039] The second heating device 19 is configured to heat the yarn Y fed from the third feed roller 18. The second heating device 19 extends, for example, along the vertical direction. The second heating device 19 will be described in more detail later.

[0040] The fourth feed roller 20 is configured to feed the yarn Y heated by the second heating device 19 to the winding device 21. For example, as shown in FIG. 2, the fourth feed roller 20 is configured to be capable of feeding one yarn Y to the winding device 21. Alternatively, the fourth feed roller 20 may be configured to be capable of feeding adjacent yarns Y each downstream in the yarn running direction. The conveying speed of the yarn Y by the fourth feed roller 20 is slower than the conveying speed of the yarn Y by the third feed roller 18. Therefore, the yarn Y is relaxed between the third feed roller 18 and the fourth feed roller 20.

[0041] The processing section 3 configured as above can perform false twist processing, for example, as follows. The yarn Y drawn between the first feed roller 11 and the second feed roller 16 is twisted by the false twist device 15. The twist formed by the false twist device 15 propagates to the twist stop guide 12, but does not propagate upstream of the twist stop guide 12 in the yarn running direction. The yarn Y to which the twist is imparted while being drawn is heated and heat-set by the first heating device 13, and then cooled by the cooling device 14. The yarn Y is untwisted downstream of the false twist device 15 in the yarn running direction, but the yarn Y maintains the wavy false twisted state due to the heat setting (i.e., the crimp of the yarn Y is maintained). The false twisted yarn Y is relaxed between the second feed roller 16 and the third feed roller 18, and is then entangled by the entanglement device 17, and is guided downstream in the yarn running direction. Through the above-described processing, the yarn Y is false-twisted to form a false-twist textured yarn Yf (see FIG. 1).

[0042] Furthermore, the false twist textured yarn Yf is heat-treated in a second heating device 19 while being relaxed between a third feed roller 18 and a fourth feed roller 20. Finally, the false twist textured yarn Yf sent from the fourth feed roller 20 is wound by a winding device 21.

[0043] The conventional heat treatment by the second heating device 19 is mainly carried out to remove residual torque in the false twist textured yarn Yf. For convenience of explanation, the false twist textured yarn Yf having a relatively large residual torque before being subjected to the heat treatment by the second heating device 19 is referred to as the pre-heat treatment false twist textured yarn Yh.

[0044] (Configuration of winding section) The configuration of the winding section 4 will be described with reference to FIG. 2. The winding section 4 has a plurality of winding devices 21. Each winding device 21 is configured to be able to wind the yarn Y onto one winding bobbin Bw. The winding device 21 has a fulcrum guide 41, a traverse device 42, and a cradle 43. The fulcrum guide 41 is a guide that serves as a fulcrum when the yarn Y is traversed. The traverse device 42 is configured to be able to traverse the yarn Y by the traverse guide 45. The cradle 43 is configured to rotatably support the winding bobbin Bw. A contact roller 46 is disposed near the cradle 43. The contact roller 46 contacts the surface of the winding package Pw to apply contact pressure. In the winding section 4 configured as above, the yarn Y sent from the fourth feed roller 20 is wound onto the winding bobbin Bw by each winding device 21 to form the winding package Pw.

[0045] (Second heating device) Next, a more specific configuration of the second heating device 19 will be described with reference to FIG. 1 and FIG. 3(a)-(c). FIG. 3(a) is a cross-sectional view of the contact heating device 19C described later, perpendicular to the vertical direction. FIG. 3(b) is a cross-sectional view of line Ab-Ab in FIG. 3(a). FIG. 3(c) is a cross-sectional view of line Ac-Ac in FIG. 3(a). As described above, the direction in which the second heating device 19 extends (hereinafter, the extension direction) is approximately parallel to the vertical direction. In FIG. 3(b) and (c), the upper side of the paper is one side in the extension direction, and the lower side of the paper is the other side in the extension direction. The one side in the extension direction corresponds to, for example, the upstream side in the yarn running direction. The other side in the extension direction corresponds to, for example, the downstream side in the yarn running direction. The direction perpendicular to both the machine frame longitudinal direction and the extension direction is the height direction (see FIG. 3(a)). In FIG. 3(a), the left side of the paper surface is one side in the height direction, and the right side of the paper surface is the other side in the height direction (the same applies to FIGS. 3(b) and 3(c), although not shown).

[0046] The second heating device 19 has, for example, a non-contact heating device 19N and a contact heating device 19C (see FIG. 1). The non-contact heating device 19N is a non-contact heating device similar to the above-described first heating device 13. The contact heating device 19C is a heating device configured to bring the traveling yarn Y into contact with a contact surface 56 described below to efficiently heat the yarn Y.

[0047] In this embodiment, the contact heating device 19C is configured to be capable of heating, for example, two yarns Y (yarns Ya and Yb; see Figs. 3(a) to 3(c)). The length of the contact heating device 19C in the extension direction is preferably 0.4 m or more and 1.6 m or less. Alternatively, the length of the contact heating device 19C in the extension direction may be, for example, 1.0 m or more and 1.5 m or less. It is preferable that the contact heating device 19C having an appropriate length in the extension direction is selected according to conditions such as the type and / or thickness of the yarn, or the yarn running speed. The contact heating device 19C has a heat source 51 and a heating section 52. The contact heating device 19C heats the yarns Ya and Yb simultaneously by bringing the running yarns Ya and Yb into contact with the heating section 52 heated by the heat source 51.

[0048] The heat source 51 is, for example, a known sheathed heater (electric heater). The sheathed heater is a device having an electric heating wire (for example, a coil) and a pipe surrounding the electric heating wire. The sheathed heater generates Joule heat when an electric current flows through the electric heating wire. The heat source 51 extends along the extension direction (see FIG. 3(b)). The heat source 51 is electrically connected to a control device 100 (see FIG. 3(b)) that controls the heating temperature of the contact heating device 19C. The control device 100 is configured to be able to set the heating temperature of the contact heating device 19C. The control device 100 controls the contact heating device 19C based on the set temperature value of the contact heating device 19C. The control device 100 may control the contact heating device 19C in consideration of, for example, the set temperature of the contact heating device 19C and the detection result by a temperature sensor (not shown) that detects the actual temperature of the heating unit 52. The control device 100 may be electrically connected to devices constituting the yarn processing machine 1 in addition to the contact heating device 19C.

[0049] The heating section 52 is configured to be heated by heat generated by the heat source 51. The heating section 52 extends in the extension direction along the heat source 51 (see Figs. 3(b) and (c)). In the extension direction, the heating section 52 has a length that is approximately the same as the length of the contact heating device 19C in the extension direction. For example, when the length of the contact heating device 19C in the extension direction is 1.0 m, the length of the heating section 52 in the extension direction is also 1.0 m. The heating section 52 has, for example, two heating members 53 (heating members 53a, 53b) and two contact blocks 54 (contact blocks 54a, 54b). The heating member 53a and the contact block 54a are members for heating the yarn Ya. The heating member 53b and the contact block 54b are members for heating the yarn Yb. The member for heating the yarn Ya and the member for heating the yarn Yb are disposed, for example, on opposite sides of the heat source 51 in the longitudinal direction of the machine.

[0050] A member for heating the yarn Ya will be described. The heating member 53a is made of a metal material with a large specific heat, such as brass. The heating member 53a extends in the extension direction along the heat source 51. The heating member 53a is arranged so as to be in contact with the heat source 51. The heating member 53a is arranged, for example, on one side of the heat source 51 in the machine base longitudinal direction (the lower side of the paper surface of FIG. 3(a)). The heating member 53a has, for example, a slit 55 (slit 55a) for forming a yarn path, which extends in the extension direction. The slit 55a is a substantially U-shaped slit in a cross section perpendicular to the extension direction. The slit 55a is open on the other side in the height direction. A contact block 54 (contact block 54a) is accommodated in the slit 55a.

[0051] The contact block 54a is a member that forms a yarn path along which the yarn Ya travels. The contact block 54a is a long member made of, for example, SUS. The contact block 54a extends at least in the extension direction. The contact block 54a is accommodated in the slit 55a. The contact block 54a is fixed to the heating member 53a in a state of contact with the heating member 53a. The contact block 54a is heated by heat transferred from the heat source 51 via the heating member 53a. The contact block 54a has a contact surface 56 (contact surface 56a) for contacting the yarn Y (yarn Ya). The contact surface 56a faces at least the other side in the height direction. The contact surface 56a is curved, for example, in a substantially U-shape when viewed from the extension direction (see FIG. 3(a)). The contact surface 56a is, for example, substantially linear in a cross section perpendicular to the machine base longitudinal direction (see FIG. 3(c)). Alternatively, the contact surface 56a may be curved in a substantially U-shape in a cross section perpendicular to the longitudinal direction of the machine base.

[0052] The member for heating the yarn Yb will be described. The heating member 53b is disposed, for example, on the other side of the heat source 51 in the machine longitudinal direction (upper side of the paper in FIG. 3(a)). The heating member 53b is in contact with the heat source 51. The heating member 53b has a slit 55b having a shape similar to that of the slit 55a. A contact block 54b having a structure similar to that of the contact block 54a is accommodated in the slit 55b. The contact block 54b has a contact surface 56b having a shape similar to that of the contact surface 56a. The contact surface 56b faces at least the other side in the height direction. Further details will be omitted.

[0053] The yarn path in and around the second heating device 19 is set as follows. The yarn path of the yarn Ya is set in advance so that, for example, the yarn Ya comes into contact with the contact surface 56a when it is assumed that the yarn Ya is running without relaxation within the second heating device 19. Similarly, the yarn path of the yarn Yb is set in advance so that, for example, the yarn Yb comes into contact with the contact surface 56b when it is assumed that the yarn Yb is running without relaxation within the second heating device 19.

[0054] In the contact heating device 19C having the above configuration, the yarn Y comes into contact with the contact surface 56 while traveling, and receives heat from the heating unit 52 via the contact surface 56 (contact method). This causes the yarn Y to be heated. In other words, the yarn path of the yarn Y is arranged so that the yarn Y comes into contact with the contact surface 56. By appropriately setting the type of yarn Y, the brand (thickness) of the yarn Y, the traveling speed of the yarn Y, and the heating temperature of the contact heating device 19C, the temperature of the yarn Y can be raised to an optimal processing temperature. In the contact heating device 19C, the heating temperature and the processing temperature may not be the same. In other words, the heating temperature may be set higher than the target value of the processing temperature.

[0055] Here, as described above, the conventional heat treatment by the contact heating device 19C is mainly performed to remove residual torque in the false twist textured yarn Yf (false twist textured yarn Yh before heat treatment). Such heat treatment is usually performed by heating the false twist textured yarn Yf to about 100 to 220°C. On the other hand, the heating temperature of the contact heating device 19C of this embodiment can be set to the same temperature as the heating temperature of the non-contact heating device 19N because the above-mentioned heat source 51 is provided. This allows the contact surface 56 of the contact heating device 19C to be raised to a temperature similar to the heating temperature. Therefore, the false twist textured yarn Yf running in contact with the contact surface 56 can also be raised to a temperature much higher than the above-mentioned about 100 to 220°C. It was not known in the past what phenomenon occurs when the false twist textured yarn Yf is heated to a high temperature.

[0056] Incidentally, there is a generally known yarn (not shown) that has variation in dyeability in the longitudinal direction and is used as a material for fabric with a heathered texture after dyeing. For convenience of explanation, such a yarn is called a thick and thin yarn, regardless of the shape, structure, and raw material of the yarn. In the method of drawing a running yarn (single yarn) while contacting it with the above-mentioned hot pins, the well-known stick-slip phenomenon is intentionally generated. This intentionally changes the running speed of the yarn that contacts the hot pins over time. As a result, in the yarn, microcrystalline parts (thin parts) that are greatly drawn and oriented in the longitudinal direction of the yarn, and non-crystalline parts (thick parts) that are not drawn as compared with the microcrystalline parts and maintain an amorphous state are alternately formed in the longitudinal direction. The dye does not easily penetrate into the microcrystalline parts, and the dye penetrates relatively easily into the non-crystalline parts. Here, in the manufacturing method of thick and thin yarn using hot pins, there is a problem that the running speed of the yarn cannot be increased in order to avoid the yarn being cut by rubbing against the hot pins.

[0057] The inventors of the present application have conducted various studies using a machine having the same configuration as the yarn processing machine 1, and have discovered a completely new method for producing thick-and-thin yarn at high speed, as described below.

[0058] (Thick and Thin Yarn Manufacturing Method) A method for producing thick and thin yarn in this embodiment will be described. For convenience of explanation, the process of producing thick and thin yarn Yt (see FIG. 1) from pre-heat-treatment false twist textured yarn Yh using the above-mentioned yarn processing machine 1 will be referred to as thick and thin processing. Pre-heat-treatment false twist textured yarn Yh has a large residual torque compared to that after the above-mentioned heat treatment. However, since the pre-heat-treatment false twist textured yarn Yh is formed by subjecting raw yarn Yr to false twist processing, it corresponds to the false twist textured yarn of the present invention. Hereinafter, the pre-heat-treatment false twist textured yarn Yh will be simply referred to as false twist textured yarn Yf.

[0059] As shown in FIG. 2, the above-mentioned processing section 3 has a false twist processing section 3A that performs false twist processing and a thick and thin processing section 3B that performs thick and thin processing. The false twist processing section 3A is disposed downstream of the yarn supplying section 2 and upstream of the thick and thin processing section 3B in the yarn running direction. The thick and thin processing section 3B is disposed downstream of the false twist processing section 3A and upstream of the winding section 4 in the yarn running direction. The false twist processing section 3A includes the first feed roller 11 to the intertwining device 17 among the components of the processing section 3. The thick and thin processing section 3B includes the third feed roller 18 to the fourth feed roller 20 among the components of the processing section 3. In this embodiment, in the yarn processing machine 1, the false twist processing section 3A false twists the raw yarn Yr to form a false twist textured yarn Yf, and the false twist textured yarn Yf is sent directly from the false twist processing section 3A to the third feed roller 18 of the thick and thin processing section 3B. Then, the false twist textured yarn Yf is subjected to thick-and-thin processing by the thick-and-thin processing section 3B.

[0060] The inventors of the present application set the manufacturing conditions of the false twist textured yarn Yf in the false twist textured section 3A to the following standard conditions, and then set the conditions of the thick and thin textured section 3B as described below. A single yarn made of synthetic fiber made of PET, a typical polyester-based material, was used as the raw yarn Yr. The raw yarn Yr was used to have a thickness such that the yarn Y after a typical false twist texture would have a thickness of 167 dtex (48 filaments). The running speed of the yarn Y (the conveying speed of the yarn Y by the second feed roller 16; the same applies below) was set to 800 m / min. The heating temperature of the first heating device 13 was set to 550°C at the inlet portion (the upstream portion in the yarn running direction) and 450°C at the outlet portion (the downstream portion in the yarn running direction). A standard disk friction type false twist device was used as the false twist device 15. The air pressure of the intertwining device 17 was set to 0.25 MPa.

[0061] When setting the conditions, the inventors of the present application used heating devices with the following lengths as the second heating device 19 in the thick-and-thin processing section 3B. That is, a non-contact heating device 19N having a length of 0.3 m in the extension direction was used. A contact heating device 19C having a length of 1.0 m in the extension direction was used. The false twist textured yarn Yf was preheated by the non-contact heating device 19N, and the false twist textured yarn Yf was further heated by the contact heating device 19C.

[0062] The inventors of the present application set the conditions for the thick-and-thin processed section 3B as follows. The inventors of the present application processed the false twist textured yarn Yf under each condition, wound it around a winding bobbin Bw, and formed a plurality of winding packages Pw. More specifically, the inventors of the present application changed the set value of the heating temperature of the second heating device 19 at least from 300°C to 400°C in 50°C increments. In other words, the winding packages Pw were formed under at least three conditions of the heating temperature of the second heating device 19: 300°C, 350°C, and 400°C. The inventors of the present application set the set value of the heating temperature of the non-contact heating device 19N and the heating temperature of the contact heating device 19C to the same temperature under each condition.

[0063] The inventors of the present application also set an overfeed rate suitable for each of the three heating temperature conditions. The overfeed rate is defined as follows when the yarn feeding speed by the third feed roller 18 arranged upstream of the second heating device 19 in the yarn running direction is faster than the yarn feeding speed by the fourth feed roller 20 arranged downstream of the second heating device 19 in the yarn running direction. That is, when the overfeed rate is OF, the yarn feeding speed by the third feed roller 18 (first yarn feeding speed) is V1, and the yarn feeding speed by the fourth feed roller 20 (second yarn feeding speed) is V2, the value of OF is calculated, for example, based on the following formula. In this case, the unit of OF is a percentage.

[0064] OF = 100 × (V1-V2) / V1

[0065] The overfeed rate suitable for each heating temperature condition is an overfeed rate at which the false twist textured yarn Yf can run in the thick-and-thin processing section 3B while being relaxed, even if the false twist textured yarn Yf is heated by the second heating device 19 and thermally shrunk. The inventors of the present application monitored the tension of the false twist textured yarn Yf using a tension sensor (not shown) and set the overfeed rate as follows so that the tension becomes zero. When the heating temperature of the second heating device 19 was 300°C, the overfeed rate was set to 3.8%. When the heating temperature of the second heating device 19 was 350°C, the overfeed rate was set to 7.0%. When the heating temperature of the second heating device 19 was 400°C, the overfeed rate was set to 15%.

[0066] The inventors of the present application produced cloth using three types of yarn Y processed at the heating temperature and overfeed rate of the second heating device 19 described above, and checked for the presence or absence of dyeing unevenness. The following description will be given with reference to the photographs shown in Figs. 4 and 5. Simply to define the left-right direction on the paper surface of the drawings, the vertical direction and the horizontal direction are defined in Figs. 4 and 5. The left-right direction on the paper surface of Figs. 4 and 5 is the horizontal direction. The up-down direction on the paper surface of Figs. 4 and 5 is the vertical direction.

[0067] The inventor of the present application used a general cylindrical knitting machine (not shown) to cylindrically knit three types of yarn Y, respectively, to form a cloth made of each of the three types of yarn Y. The inventor of the present application dyed the formed cloth (see FIG. 4). As a dyeing method, heat dyeing, which is a general method for dyeing polyester-based synthetic fibers, was adopted. In order from the left side of the paper in FIG. 4, the heating temperatures of the second heating device 19 when the yarn Y constituting the cloth was formed are 300°C, 350°C, and 400°C. The cloth shown on the left side of the paper in FIG. 4 had no heathered feel (uneven dyeing) at all. In the cloth shown in the center of the paper in the left-right direction of FIG. 4, a slight pattern like uneven dyeing was observed, but no clear heathered feel was observed. In the cloth shown on the right side of the paper in FIG. 4 and in FIG. 5, a clear heathered feel was observed. That is, by processing the false twist textured yarn Yf with the heating temperature of the second heating device 19 set to 400°C, a thick and thin yarn Yt having uneven dyeability in the longitudinal direction was formed.

[0068] (Why Thick and Thin Yarn was created) The inventors of the present application have considered the reason why thick and thin yarn Yt, which is a material for fabric having a heathered texture, is formed under the above-mentioned processing conditions as follows. Fig. 6 is an explanatory diagram regarding the consideration of the principle of forming thick and thin yarn Yt.

[0069] First, as a premise, polyester synthetic fibers have the property that their dyeability (ease of being dyed) changes depending on the change in the crystal state. Specifically, the crystal state of polyester synthetic fibers can be an amorphous state in which the crystals are randomly oriented, or a microcrystalline state in which the crystals are partially oriented regularly. Since the bonding force between molecules is weak in the amorphous state parts, dyes are relatively more likely to penetrate into the amorphous state parts compared to the microcrystalline state parts. For this reason, the amorphous state parts are more easily dyed (i.e., have higher dyeability) than the microcrystalline state parts.

[0070] There are several methods for changing the crystalline state of polyester-based synthetic fibers. For example, when the yarn Y is false-twisted by the false-twisting unit 3A, the yarn Y is stretched while being heated, so that the orientation of the crystals in the yarn Y becomes regular, and the crystalline state of the yarn Y changes to a microcrystalline state. The crystalline state of polyester-based synthetic fibers can also change when heated to a predetermined temperature or higher. For example, it is believed that when the false-twisted yarn Yf is heated to a temperature at or near the melting point, the orientation of the crystals becomes random, and the crystalline state changes from a microcrystalline state to an amorphous state.

[0071] On the other hand, the yarn Y is thermally shrunk when heated to a high temperature. Therefore, when the false twisted yarn Yf is heated to a predetermined temperature or higher, it undergoes a change in dyeability and is allowed to run while undergoing thermal shrinkage. The inventors of the present application have considered that by feeding such false twisted yarn Yf while relaxing it at a high overfeed rate of a predetermined value or higher, a thick and thin yarn Yt can be manufactured based on the following principle. That is, the false twisted yarn Yf running while being largely relaxed runs in a slightly wavy manner, and is divided into a portion that firmly contacts the contact surface 56 and a portion that does not contact it much in the longitudinal direction. The portion of the false twisted yarn Yf that firmly contacts the contact surface 56 becomes hot, undergoes thermal shrinkage, and increases in thickness (see, for example, the first yarn portion Ym shown in FIG. 6). Then, the first yarn portion Ym is more likely to come into contact with the contact surface 56. As a result, the temperature rises to a predetermined temperature or higher in the longitudinal direction, centered on the first yarn portion Ym, and thermal shrinkage (and change in dyeability) progresses further. On the other hand, the portion that is not in contact with the contact surface 56 as much as the first yarn portion Ym (for example, see the second yarn portion Yn shown in FIG. 6) is less likely to become hot, and the progress of thermal shrinkage is suppressed compared to the first yarn portion Ym. Therefore, the thickness of the second yarn portion Yn is less likely to increase, and thermal shrinkage (and change in dyeability) is further suppressed compared to the first yarn portion Ym. In this way, the first yarn portion Ym and the second yarn portion Yn are arranged alternately in the longitudinal direction. As a result, in the false twist textured yarn Yf, it is possible to alternately form portions in which the dyeability changes significantly and portions in which the change is relatively small in the longitudinal direction. As a result, a thick and thin yarn Yt is produced. The inventor of the present application considered the above.

[0072] The inventors of the present application have considered that, even under conditions other than those described above, thick and thin yarn Yt can be produced by appropriately setting the processing conditions in the thick and thin processing section 3B. As a premise, the false twist textured yarn Yf formed by false twisting raw yarn Yr made of polyester synthetic fiber has a property that the dyeability changes and heat shrinks when heated to a predetermined temperature or higher. In addition, in the thick and thin processing section 3B, it is necessary to set the heating temperature of the second heating device 19 so that the false twist textured yarn Yf is at least partially heated to a predetermined temperature or higher. In addition, in order to send the false twist textured yarn Yf, which runs while thermally shrinking, downstream in the yarn running direction while relaxing it, it is necessary to maintain the overfeed rate at a predetermined value or higher.

[0073] The predetermined temperature is, for example, the melting point of the material (PET, etc.) of the false twist textured yarn Yf. More specifically, the melting point of PET (homopolymer type) is, for example, 255°C or higher and 260°C or lower. Alternatively, the melting point may be higher than 260°C.

[0074] The material of the false twist textured yarn Yf is preferably a material such as PET, whose dyeability changes as a result of a change in its crystalline state when heated to a predetermined temperature or higher.

[0075] Specifically, the overfeed rate is preferably 15% or more. If the overfeed rate is low, the following problems may occur, for example. That is, the false twist textured yarn Yf may not substantially relax due to thermal shrinkage, and thick-and-thin yarn Yt may not be formed. In addition, excessive tension may be applied to the false twist textured yarn Yf due to thermal shrinkage, which may cause yarn breakage.

[0076] The contact surface 56 of the contact block 54 of the contact heating device 19C may be linear in a cross section perpendicular to the machine longitudinal direction as shown in FIG. 3(c), but is more preferably curved to be warped in a substantially U-shape. This makes it easier for the false twist textured yarn Yf to come into contact with the contact surface 56, further increasing the heating efficiency. Generally, the smaller the radius of curvature in the cross section, the greater the frictional resistance (in other words, running resistance) applied from the contact surface 56 to the running yarn Y. This may cause the yarn Y on the contact surface 56 to slow down due to the running resistance and become unnecessarily loose, or the yarn may be easily broken due to the slack. Therefore, when a configuration in which the contact surface 56 is curved is applied, it is required to appropriately set the radius of curvature and take measures to reduce the friction coefficient of the contact surface 56 so that the running resistance described above does not become too large.

[0077] In order to produce the thick and thin yarn Yt at high speed, the yarn running speed is preferably 600 m / min or more, and more preferably 800 m / min or more.

[0078] The second heating device 19 preferably has a contact heating device 19C. The contact heating device 19C can quickly heat the false twist textured yarn Yf to a high temperature. The non-contact heating device 19N can preheat the false twist textured yarn Yf, but the non-contact heating device 19N does not have to be provided. In other words, the false twist textured yarn Yf may be heated only by the contact heating device 19C. The length in the extension direction of the non-contact heating device 19N is not limited to 0.3 m. The length in the extension direction of the contact heating device 19C is not limited to 1.0 m. The yarn running speed is appropriately set according to the length in the extension direction of the second heating device 19 and / or the heating temperature, thereby making it possible to produce a thick and thin yarn Yt.

[0079] The heating temperature of the contact heating device 19C (i.e., the set temperature of the contact block 54 of the heating section 52) is preferably 400°C or higher. However, this is not limited thereto. Even if the heating temperature of the contact heating device 19C is less than 400°C, it is sufficient that the false twist textured yarn Yf is at least partially heated to a predetermined temperature or higher. For example, the heating temperature of the contact heating device 19C may be 350°C or higher. For example, the inventors of the present application consider that if the false twist textured yarn Yf is thinner than the above-mentioned 167 dtex or the yarn running speed is slower than the above-mentioned 800 m / min, the thick and thin yarn Yt can be produced even if the heating temperature of the contact heating device 19C is 350°C. This is also inferred from the fact that a slight pattern like uneven dyeing was observed in the fabric shown in the center of the left-right direction of the paper in FIG. 4 (the heating temperature of the contact heating device 19C is 350°C), as described above.

[0080] Moreover, it is more preferable that the thickness of the false twist textured yarn Yf is 50 dtex or more. In this embodiment, the false twist textured yarn Yf can be efficiently heated by the contact heating device 19C. Therefore, even when a thick false twist textured yarn Yf is used, a thick and thin yarn with stable quality can be produced.

[0081] As described above, the false twist textured yarn Yf, which has already been false twisted, is heated to a predetermined temperature or higher, causing a change in dyeability and allowing it to run while undergoing thermal shrinkage. By feeding such false twist textured yarn Yf while relaxing it at a high overfeed rate of 15% or more, thick and thin yarn Yt, which is a material for fabrics with a heathered texture, can be produced. By maintaining such a high overfeed rate, the yarn Y can be run at high speed. Therefore, thick and thin yarn Yt can be produced at high speed.

[0082] In addition, the false twist textured yarn Yf is composed of a single yarn. That is, the thick-and-thin yarn Yt can be produced by simply heating a single false twist textured yarn Yf while relaxing it. Therefore, the thick-and-thin yarn Yt can be produced by a simple configuration and method.

[0083] In this embodiment, the false twist textured yarn Yf can be fed at a high speed of 600 m / min or more, and therefore the thick and thin yarn Yt can be produced at high speed.

[0084] In addition, the material of the false twist textured yarn Yf has a property that the dyeability changes due to a change in the crystalline state when heated to a predetermined temperature or higher. Materials such as PET, whose dyeability changes depending on the crystalline state, are commonly known as polyester-based synthetic fiber materials. In this embodiment, the dyeability of the false twist textured yarn Yf can be intentionally varied in the longitudinal direction by a simple method of running the false twist textured yarn Yf at a predetermined overfeed rate while heating it.

[0085] Furthermore, by heating the false twist textured yarn Yf to a temperature equal to or higher than the melting point (for example, 255° C.) of the material of the false twist textured yarn Yf, the crystalline state of the material can be significantly changed.

[0086] In addition, in this embodiment, the false twist textured yarn Yf can be effectively heated by heat conduction through the contact surface 56 of the contact block 54. As a result, even if the running speed of the false twist textured yarn Yf is high, the false twist textured yarn Yf can be heated to the required temperature. Therefore, the thick and thin yarn Yt can be produced at high speed.

[0087] In addition, since the temperature setting value of the contact block 54 of the heating unit 52 is high at 350°C or higher (it can be 400°C or higher), the false twist textured yarn Yf is effectively heated. As a result, even if the running speed of the false twist textured yarn Yf is fast, the false twist textured yarn Yf can be heated to the required temperature. Therefore, the thick and thin yarn Yt can be produced at high speed.

[0088] Furthermore, in this embodiment, even when a thick false twist textured yarn Yf (for example, 50 dtex or more) is used, a thick and thin yarn Yt with stable quality can be produced.

[0089] In addition, in this embodiment, while the false twist textured yarn Yf is being formed, the formed false twist textured yarn Yf can be used as is to produce the thick-and-thin yarn Yt. In such a production method, it is particularly effective to be able to produce the thick-and-thin yarn Yt at high speed.

[0090] Furthermore, in this embodiment, the yarn path of the false twist textured yarn Yf is set in advance so that the false twist textured yarn Yf comes into contact with the contact surface 56 when it is assumed that the false twist textured yarn Yf is running without relaxation within the second heating device 19. Therefore, an appropriate yarn path can be set easily compared to a method in which the false twist textured yarn Yf is brought into contact with the contact surface 56 only when the false twist textured yarn Yf is running in a relaxed state.

[0091] Next, a modified example of the embodiment will be described, in which the same reference numerals will be used to designate components similar to those in the embodiment, and the description thereof will be omitted as appropriate.

[0092] (1) In the above embodiment, the overfeed rate is preferably 15% or more. However, this is not limited to this. The false twist textured yarn Yf may be sent downstream in the yarn running direction while being relaxed according to the rate of thermal contraction of the false twist textured yarn Yf heated by the second heating device 19.

[0093] (2) In the above embodiment, the yarn traveling speed is preferably 600 m / min or more. However, this is not limited to this. The yarn traveling speed may be appropriately set depending on the length of the second heating device 19 in the extension direction and / or the heating temperature.

[0094] (3) In the above embodiments, the melting point of the material of the false twist textured yarn Yf is about 255 to 260°C. However, this is not limited to this. The predetermined temperature is, for example, the melting point of the material of the false twist textured yarn Yf (PET, etc.). However, this is not limited to this. The temperature equal to or higher than the predetermined temperature may be any temperature at which the dyeability of the material of the false twist textured yarn Yf changes and the material undergoes thermal shrinkage.

[0095] (4) In the above embodiments, the dyeability of the false twist textured yarn Yf changes when the material is heated to a predetermined temperature or higher, due to a change in the crystalline state. However, this is not limited to this. The material of the false twist textured yarn Yf may have a property that the dyeability changes due to a phenomenon other than a change in the crystalline state when heated to a predetermined temperature or higher.

[0096] (5) In the above embodiments, the contact block 54 is provided as a member having the contact surface 56. However, this is not limited to this. Instead of the contact block 54, for example, a stainless steel plate (not shown) that is processed into a substantially U-shape when viewed from the extension direction may be housed in the slit 55 (see, for example, Japanese Patent Application Laid-Open No. 2002-194631). A contact surface (not shown) may be formed on such a stainless steel plate.

[0097] (6) In the above embodiments, the yarn path of the false twist textured yarn Yf is arranged so that the false twist textured yarn Yf comes into contact with the contact surface 56 provided in the second heating device 19. The yarn path is also set in advance so that the false twist textured yarn Yf comes into contact with the contact surface 56 when it is assumed that the false twist textured yarn Yf runs without relaxation in the second heating device 19. However, this is not limited to this. The yarn path of the false twist textured yarn Yf may be set so that it is slightly separated from the contact surface 56 (i.e., so that the false twist textured yarn Yf is adjacent to the contact surface 56) when it is assumed that the false twist textured yarn Yf runs without relaxation in the second heating device 19. Even in this case, a part of the false twist textured yarn Yf in the longitudinal direction can be brought into contact with the contact surface 56 by running the false twist textured yarn Yf in a wavy manner in the second heating device 19.

[0098] (7) In the above-described embodiment, the thick-and-thin yarn Yt was obtained when the manufacturing conditions of the false twist textured yarn Yf in the false twist textured section 3A were set to the standard conditions as described above. However, it is expected that the thick-and-thin yarn Yt can be obtained under manufacturing conditions other than the above-described manufacturing conditions by appropriately setting the processing conditions in the thick-and-thin textured section 3B.

[0099] (8) In the above-described embodiments, the second heating device 19 is configured to be capable of heating two strands of yarn Y. However, this is not limited to this. The second heating device 19 may be configured to be capable of heating one strand of yarn Y. Alternatively, the second heating device 19 may be configured to be capable of heating three or more strands of yarn Y.

[0100] (9) The configuration of the false twist processing unit 3A is not limited to the above. For example, the first heating device 13 may be a known contact-type dowsum heater. The thick-and-thin processing unit 3B may be applied to a yarn processing machine (not shown) having a different configuration, not limited to the yarn processing machine 1. For example, the present invention may be provided with the thick-and-thin processing unit 3B in the rewinder described in Publication No. 2019 / 225138. [Explanation of symbols]

[0101] 1 Yarn processing machine 18 Third feed roller (first yarn feeding device) 19 Second heating device (heating device) 20 Fourth feed roller (second yarn feeding device) 51 Heat source 52 Heating section 56 Contact surface Y Thread Yf false twist textured yarn Yr raw yarn Yt Thick and Thin Yarn

Claims

1. A method for producing a thick and thin yarn, wherein the yarn has variations in dyeability along its longitudinal direction, The aforementioned yarn is a false-twisted yarn formed by subjecting a raw yarn made of polyester synthetic fibers to a false-twist process. The false-twisted yarn is fed downstream in the yarn direction by a first yarn feeding device that feeds the false-twisted yarn downstream in the yarn direction in which the false-twisted yarn travels, and a second yarn feeding device that is positioned downstream of the first yarn feeding device in the yarn direction, and the false-twisted yarn is heated by a heating device positioned between the first yarn feeding device and the second yarn feeding device in the yarn direction. The heating device comprises a heat source and a contact surface formed in a heating section heated by the heat source and extending along the yarn running direction, and arranged to come into contact with the false-twisted yarn. The heating temperature of the heating device is set such that the false-twisted yarn is heated at least partially to a temperature above a predetermined temperature that causes a change in dyeability and thermal shrinkage within the heating device. A method for manufacturing a thick and thin yarn, characterized by maintaining an overfeed rate of 15% or more, calculated based on a first yarn feeding speed by the first yarn feeding device and a second yarn feeding speed by the second yarn feeding device that is slower than the first yarn feeding speed, thereby loosening the false-twisted yarn as it runs while feeding it downstream in the yarn running direction.

2. The method for producing a thick and thin yarn according to claim 1, characterized in that the false-twisted yarn consists of a single yarn.

3. The method for producing a thick and thin yarn according to claim 2, characterized in that the first yarn feeding speed and the second yarn feeding speed are 600 m / min or more.

4. The method for producing a thick and thin yarn according to claim 1, characterized in that the material of the false-twisted yarn changes its crystalline state when heated above the predetermined temperature, thereby changing its dyeability.

5. The method for producing a thick and thin yarn according to claim 2, characterized in that the material of the false-twisted yarn changes its crystalline state when heated above the predetermined temperature, thereby changing its dyeability.

6. The method for producing a thick and thin yarn according to claim 3, characterized in that the material of the false-twisted yarn changes its crystalline state when heated above the predetermined temperature, thereby changing its dyeability.

7. The method for producing a thick and thin yarn according to claim 4, characterized in that the predetermined temperature is the melting point of the material of the false-twisted yarn.

8. The method for producing a thick and thin yarn according to claim 5, characterized in that the predetermined temperature is the melting point of the material of the false-twisted yarn.

9. The method for producing a thick and thin yarn according to claim 6, characterized in that the predetermined temperature is the melting point of the material of the false-twisted yarn.

10. The method for producing a thick and thin yarn according to claim 7, characterized in that the melting point is 255°C or higher.

11. The method for producing a thick and thin yarn according to claim 8, characterized in that the melting point is 255°C or higher.

12. The method for producing a thick and thin yarn according to claim 9, characterized in that the melting point is 255°C or higher.

13. The method for manufacturing a thick and thin yarn according to claim 10, characterized in that the temperature setting value of the heating section in the heating device is 350°C or higher.

14. The method for manufacturing a thick and thin yarn according to claim 11, characterized in that the set value of the temperature of the heating section in the heating device is 350°C or higher.

15. The method for manufacturing a thick and thin yarn according to claim 12, characterized in that the set value of the temperature of the heating section in the heating device is 350°C or higher.

16. The method for manufacturing a thick and thin yarn according to claim 13, characterized in that the temperature setting value of the heating section in the heating device is 400°C or higher.

17. The method for manufacturing a thick and thin yarn according to claim 14, characterized in that the set value of the temperature of the heating section in the heating device is 400°C or higher.

18. The method for manufacturing a thick and thin yarn according to claim 15, characterized in that the set value of the temperature of the heating section in the heating device is 400°C or higher.

19. The method for producing a thick and thin yarn according to claim 13, characterized in that the thickness of the false-twisted yarn is 50 dtex or more.

20. The method for producing a thick and thin yarn according to claim 14, characterized in that the thickness of the false-twisted yarn is 50 dtex or more.

21. The method for producing a thick and thin yarn according to claim 15, characterized in that the thickness of the false-twisted yarn is 50 dtex or more.

22. The method for producing a thick and thin yarn according to claim 16, characterized in that the thickness of the false-twisted yarn is 50 dtex or more.

23. The method for producing a thick and thin yarn according to claim 17, characterized in that the thickness of the false-twisted yarn is 50 dtex or more.

24. The method for producing a thick and thin yarn according to claim 18, characterized in that the thickness of the false-twisted yarn is 50 dtex or more.

25. A method for manufacturing a thick and thin yarn according to any one of claims 1 to 24, characterized in that the raw yarn is false-twisted upstream of the first yarn feeding device in the yarn travel direction to form the false-twisted yarn, while the false-twisted yarn is traveled toward the first yarn feeding device.

26. A method for manufacturing a thick and thin yarn according to any one of claims 1 to 24, characterized in that the yarn path of the false-twist yarn is set in advance so that the false-twist yarn contacts the contact surface when it is assumed that the false-twist yarn is running without becoming slack in the heating device.

27. ​​The method for manufacturing a thick and thin yarn according to claim 25, characterized in that the yarn path of the false-twist yarn is set in advance so that the false-twist yarn contacts the contact surface when it is assumed that the false-twist yarn is running without becoming slack in the heating device.

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