Claims:I/We claim:

1. A yarn winding machine (1) that performs yarn winding process in which a package (P) is formed while traversing a yarn and winding the yarn onto a bobbin (Bw), comprising:
a traverse guide (32) that causes the yarn to traverse;
a traverse driving section (33) that reciprocally drives the traverse guide (32) in a predetermined traverse direction;
a setting section (4) that independently sets, as target values of a traverse angle, at least an initial value of a reference traverse angle and an initial value of the traverse angle that is different from the reference traverse angle, the traverse angle being an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package (P), and is an angle formed between a plane perpendicular to the longitudinal central axis of the package (P) and the yarn that is being traversed; and
a controlling section (30) that
acquires, based on information indicating an end portion traverse angle, an end portion speed pattern that is a speed pattern of the traverse guide (32) at an end portion in the traverse direction;
acquires, based on information indicating the end portion speed pattern and the reference traverse angle, a central portion speed pattern that is a speed pattern of the traverse guide (32) at the central portion in the traverse direction;
controls the traverse driving section (33) based on the central portion speed pattern and the end portion speed pattern; and
performs, by changing the reference traverse angle from the initial value during the yarn winding process, an interlinking control in which the end portion traverse angle is increased when the reference traverse angle is increased, and the end portion traverse angle is decreased when the reference traverse angle is decreased.

2. The yarn winding machine (1) as claimed in Claim 1, wherein the setting section (4) performs an operation of switching a control mode of the controlling section (30) between
an interlinking mode in which the interlinking control is performed, and
a constant end portion traverse angle mode in which the end portion traverse angle is maintained at a constant value during the yarn winding process.

3. The yarn winding machine (1) as claimed in Claim 1 or 2, wherein the controlling section (30) is capable of performing step precision winding in which a certain winding ratio, which is a ratio between number of rotations of the package (P) per unit time and number of reciprocations of the traverse guide (32) per unit time, is changed in a stepped manner as a diameter of the package (P) increases during the yarn winding process, and
the controlling section (30) performs the interlinking control during the step precision winding.

4. The yarn winding machine (1) as claimed in one of Claims 1 to 3, wherein the setting section (4) sets a predetermined minimum end portion traverse angle, and the controlling section (30) performs settings such that the end portion traverse angle does not decrease below the minimum end portion traverse angle during the interlinking control.

5. The yarn winding machine (1) as claimed in one of Claims 1 to 4, wherein the setting section (4) sets a predetermined maximum end portion traverse angle, and the controlling section (30) performs settings such that the end portion traverse angle does not exceed the maximum end portion traverse angle during the interlinking control.

6. The yarn winding machine (1) as claimed in one of Claims 1 to 5, wherein the controlling section (30) controls the traverse driving section (33) to perform a reversal control in which the traverse guide (32) that is traveling outward in the traverse direction at a predetermined speed is caused to decelerate, travel inwardly in a reverse direction, and re-accelerate up to the predetermined speed, and sets a length of a reversal area across which the traverse guide (32) moves between start of deceleration of the traverse guide (32) and end of the re-acceleration during the reversal control to a constant value regardless of a value of the end portion traverse angle.

7. The yarn winding machine (1) as claimed in one of Claims 1 to 5, wherein the controlling section (30) controls the traverse driving section (33) to perform a reversal control in which the traverse guide (32) that is traveling outward in the traverse direction at a predetermined speed is caused to decelerate, travel inwardly in a reverse direction, and re-accelerate to the predetermined speed, and sets a magnitude of the deceleration and acceleration of the traverse guide (32) between a start of deceleration of the traverse guide (32) to an end of re-acceleration during the reversal control to a constant value regardless of a value of the end portion traverse angle.

8. A yarn winding method for performing a yarn winding process in which a package (P) is formed while traversing a traveling yarn in a predetermined direction by using a traverse guide (32) and winding the yarn onto a rotating bobbin (Bw), comprising:
setting independently, as target values of a traverse angle, at least an initial value of a reference traverse angle and an initial value of the traverse angle that is different from the reference traverse angle, the traverse angle being an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package (P), and is an angle formed between a plane perpendicular to the longitudinal central axis of the package (P) and the yarn that is being traversed;
acquiring, based on information indicating the end portion traverse angle, an end portion speed pattern that is a speed pattern of the traverse guide (32) at an end portion in the traverse direction;
acquiring, based on information indicating the end portion speed pattern and the reference traverse angle, a central portion speed pattern that is a speed pattern of the traverse guide (32) at a central portion in the traverse direction;
causing the traverse guide (32) to travel reciprocally based on the central portion speed pattern and the end portion speed pattern; and
increasing the end portion traverse angle when the reference traverse angle is increased and decreasing the end portion traverse angle when the reference traverse angle is decreased by changing the reference traverse angle from an initial value thereof during the yarn winding process.
, Description:BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a yarn winding machine and a yarn winding method.

2. Description of the Related Art
A yarn winding device disclosed in Japanese Patent Application Laid-Open No. 2010-260729 winds a yarn on a rotating bobbin to form a package. When winding the yarn, the yarn is traversed by using a traverse guide that reciprocates along the axial direction of the bobbin. A controlling section controls a motor that drives the traverse guide. The controlling section controls a moving speed (traversing speed) of the traverse guide based on a predetermined speed pattern. Accordingly, a traverse angle determined by a ratio between a circumferential speed and the traversing speed of the package is controlled. The traverse angle is an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package, and is an angle formed between the plane perpendicular to the longitudinal central axis of the package and the traversed yarn. Furthermore, the controlling section can set a target value of the traverse angle at end portions in an axial direction of the package (end portion traverse angle) independently of an average target value of the traverse angle in the entire axial direction of the package (reference traverse angle). Consequently, the degree of freedom of controlling the traverse angle is improved. As a specific example, performing the following controls becomes possible.
For example, when performing step precision winding (a type of winding type in which a winding ratio, which is a ratio of the number of rotations of the package per unit time and the number of traverses per unit time is changed in stepped manner), which is a known type of yarn winding, the actual traverse angle changes with the increase in a package diameter. If a trajectory of the yarn at the end portion of the package changes due to such a change in the traverse angle over time, the so-called step winding (unevenness of the package end surface) may occur.
To address this issue, the controlling section disclosed in Japanese Patent Application Laid-Open No. 2010-260729 sets the end portion traverse angle to a constant value. Accordingly, a speed pattern of the traverse guide at the end portion in the axial direction of the package is maintained constant. Consequently, the trajectory of the yarn at the end portion of the package is retained constant, and the occurrence of the step winding is suppressed.
Generally, when the traverse angle changes, density (winding density) of the formed package, too, changes. Specifically, when the traverse angle is large, the winding density is low, and when the traverse angle is small, the winding density is high. Therefore, with an aim to obtain a package having a desired winding density, there is a demand for changing the reference traverse angle during the yarn winding process. However, when the reference traverse angle is changed during the yarn winding process in such a manner, if the end portion traverse angle is maintained constant as explained in Japanese Patent Application Laid-Open No. 2010-260729, the traverse angle at the central portion and the traverse angle at the end portions of the package can differ significantly. When such significant difference occurs, there is a possibility that the winding density is significantly different at the central portion and the end portions of the package. Consequently, problems such as uneven winding density in the axial direction of the package and deterioration of the package shape may occur. Such problems are not limited to the step precision winding. That is, they can occur in in other yarn winding methods as well.

SUMMARY OF THE INVENTION
One object of the present invention is to suppress occurrence of a significant difference in a traverse angle at a central portion and a traverse angle at an end portion of a package.
According to one aspect of the present invention, a yarn winding machine that performs yarn winding process in which a package is formed while traversing a yarn and winding the yarn onto a bobbin includes a traverse guide that causes the yarn to traverse; a traverse driving section that reciprocally drives the traverse guide in a predetermined traverse direction; a setting section that independently sets, as target values of a traverse angle, at least an initial value of a reference traverse angle and an initial value of the traverse angle that is different from the reference traverse angle, the traverse angle being an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package, and is an angle formed between a plane perpendicular to the longitudinal central axis of the package and the yarn that is being traversed; and a controlling section. The controlling section acquires, based on information indicating an end portion traverse angle, an end portion speed pattern that is a speed pattern of the traverse guide at an end portion in the traverse direction; acquires, based on information indicating the end portion speed pattern and the reference traverse angle, a central portion speed pattern that is a speed pattern of the traverse guide at the central portion in the traverse direction; controls the traverse driving section based on the central portion speed pattern and the end portion speed pattern; and performs, by changing the reference traverse angle from the initial value during the yarn winding process, an interlinking control in which the end portion traverse angle is increased when the reference traverse angle is increased, and the end portion traverse angle is decreased when the reference traverse angle is decreased.
According to another aspect of the present invention, a yarn winding method for performing a yarn winding process in which a package is formed while traversing a traveling yarn in a predetermined direction by using a traverse guide and winding the yarn onto a rotating bobbin includes setting independently, as target values of a traverse angle, at least an initial value of a reference traverse angle and an initial value of the traverse angle that is different from the reference traverse angle, the traverse angle being an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package, and is an angle formed between a plane perpendicular to the longitudinal central axis of the package and the yarn that is being traversed; acquiring, based on information indicating the end portion traverse angle, an end portion speed pattern that is a speed pattern of the traverse guide at an end portion in the traverse direction; acquiring, based on information indicating the end portion speed pattern and the reference traverse angle, a central portion speed pattern that is a speed pattern of the traverse guide at a central portion in the traverse direction; causing the traverse guide to travel reciprocally based on the central portion speed pattern and the end portion speed pattern; and increasing the end portion traverse angle when the reference traverse angle is increased and decreasing the end portion traverse angle when the reference traverse angle is decreased by changing the reference traverse angle from an initial value thereof during the yarn winding process.
The above and other objects, features, advantages and technical and industrial significance of this invention will be better understood by reading the following detailed description of presently preferred embodiments of the invention, when considered in connection with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a front view of an automatic winder according to an embodiment of the present invention.
FIG. 2 is a front view of a winding unit.
FIG. 3 is an enlarged view of a traversing device and a peripheral configuration thereof.
FIG. 4 is an enlarged view of a setting section.
FIG. 5 is a graph showing a speed pattern of a traverse guide.
FIG. 6 is a diagram for explaining step precision winding.
FIGS. 7A and 7B are graphs showing a relationship of a reference traverse angle and an end portion traverse angle with the thickness of a yarn layer when an end portion traverse angle is set constant.
FIGS. 8A and 8B are diagrams for explaining a problem that may occur when the end portion traverse angle is set constant.
FIG. 9 is an explanatory diagram of the setting section when a control mode is set to an interlinking mode.
FIGS. 10A and 10B are graphs showing change in the reference traverse angle and change in the end traverse angle.
FIG. 11 is a graph showing a speed pattern used when the control mode is set to the interlinking mode.
FIG. 12 is a graph showing a speed pattern used at the end portion.
FIG. 13 is an explanatory diagram of a setting section according to a modification.
FIGS. 14A and 14B are graphs showing change in the reference traverse angle and change in the end traverse angle according to the modification.
FIG. 15 is a graph showing a speed pattern used at the end portion according to another modification.

DETAILED DESCRIPTION
Exemplary embodiments of the present invention are explained below. Note that, in FIG. 1, a left-right direction on the paper is shown is a left-right direction, and a direction in which the gravitational force acts is shown as an up-down direction.
Schematic Structure of Automatic Winder
First, a schematic structure of an automatic winder 1 (yarn winding machine according to the present invention) will be explained with reference to FIG. 1. FIG. 1 is a front view of the automatic winder 1 according to an embodiment of the present invention. The automatic winder 1 includes a plurality of winding units 2 and a main control device 3.
The winding units 2 is arranged in the left-right direction. Each of the winding units 2 performs yarn winding process in which a yarn Y that is drawn from a yarn supplying bobbin Bs is wound onto a rotating winding bobbin Bw ("bobbin" according to the present invention) to form a package P. The main control device 3, for example, is arranged on the left of the winding units 2. The main control device 3 is electrically connected to a unit controller 30 ("controlling section" according to the present invention. See FIG. 3) provided in each winding unit 2, and communicates with each unit controller 30. The main control device 3 mainly includes a setting section 4 and a storage section 5. The setting section 4 collectively sets winding conditions (for example, a traverse angle explained later) and the like for the winding units 2. The setting section 4 includes a display panel 4a that displays the winding conditions and the like, and an operation panel 4b that is constituted by a plurality of input keys and the like for an operator to input the winding conditions. The setting section 4 is configured so that the operator can set the winding conditions and the like by operating the operation panel 4b while looking at the display panel 4a. The winding conditions and the like that are set by using the setting section 4 are stored in the storage section 5. Alternatively, the setting section 4, for example, can independently set the winding conditions and the like of the corresponding winding unit 2.
Winding Unit
A configuration of the winding unit 2 will be explained below with reference to FIG. 2. FIG. 2 is a front view of the winding unit 2.
The winding unit 2 unwinds the yarn Y from the yarn supplying bobbin Bs arranged at a lower end portion thereof and winds the unwound yarn onto the winding bobbin Bw arranged at an upper end thereof to form the package P. As shown in FIG. 2, the winding unit 2 includes a bobbin supporting section 21, a traversing device 22, a contact roller 23, the unit controller 30, and the like. The winding unit 2 unwinds the yarn Y from the yarn supplying bobbin Bs that is supported by the bobbin supporting section 21 and winds the yarn Y around the winding bobbin Bw, which rotates when in contact with the contact roller 23, while the traversing device 22 traverses the yarn Y . The winding bobbin Bw is rotatably supported by a cradle 24. The cradle 24, for example, is constituted so as to be pivotable according to the change in a diameter of the package P. A package driving motor 41 that rotationally drives the package P is coupled to the cradle 24. The package driving motor 41 rotates a not-shown support member that holds the package P. The package P rotates in synchronization with the rotation of the not-shown support member. The package driving motor 41 includes, for example, a sensor 42 (see FIG. 3) as a detecting section that detects an angular velocity (rotational speed) of a rotor of the package driving motor 41. The package driving motor 41 is electrically connected to the unit controller 30. Moreover, a sensor 43 (see FIG. 3) is provided near the contact roller 23 as a detecting section that detects, for example, an angular velocity (rotational speed) of the contact roller 23. The sensor 43 is electrically connected to the unit controller 30.
The bobbin supporting section 21 supports the yarn supplying bobbin Bs. The traversing device 22 includes a traverse guide 32 for traversing the yarn Y. The traversing device 22 traverses the yarn Y in a direction that is substantially parallel to the axial direction of the winding bobbin Bw (bobbin axial direction) by driving the traverse guide 32 reciprocally. When the contact roller 23 contacts the surface of the winding bobbin Bw (package P), it is rotationally driven by a frictional force received from the package P. Alternatively, the winding bobbin Bw can be caused to rotate upon contact by rotationally driving the contact roller 23 by a not-shown motor. In such a configuration, a motor is coupled to the contact roller 23 as a driving source to rotationally drive the contact roller 23. When the contact roller 23 contacts the surface of the winding bobbin Bw (package P), and the winding bobbin Bw that is in contact with the contact roller 23 is driven by a frictional force. The winding bobbin Bw can be rotationally driven by using such a configuration.
In the yarn traveling direction, a yarn clearer 25 that monitors the traveling yarn Y unwound from the yarn supplying bobbin Bs and detects a defect in the yarn Y is arranged between the bobbin supporting section 21 and the traversing device 22. The yarn clearer 25 includes a not-shown cutter that can cut the traveling yarn Y. When the yarn is cut by the cutter of the yarn clearer 25 or when a yarn breakage occurs due to other causes, the winding unit 2 performs a yarn joining process. The yarn joining process involves joining the yarn Y (a lower yarn Y1) on the yarn supplying bobbin Bs side and the yarn Y (an upper yarn Y2) on the winding bobbin Bw side. As a configuration for the yarn joining process, the winding unit 2 includes a yarn joining device 26, a lower yarn suction 27, and an upper yarn suction 28. The lower yarn suction 27 sucks and holds the lower yarn Y1 and guides the lower yarn Y1 to the yarn joining device 26. The upper yarn suction 28 sucks and holds the upper yarn Y2 and guides the upper yarn Y2 to the yarn joining device 26. The yarn joining device 26 performs yarn joining by using, for example, compressed air. The yarn joining device 26 blows compressed air onto the lower yarn Y1 and the upper yarn Y2. Once both the yarn ends are untangled, the yarn joining device 26 blows compressed air onto both the yarn ends to cause both the yarn ends to intertwine, thereby performing the yarn joining.
The unit controller 30 includes a not-shown CPU, ROM, RAM, and the like. The CPU of the unit controller 30 controls each of the included units according to a computer program stored in the ROM. The unit controller 30 is electrically connected to the main control device 3 and performs communication with the main control device 3.
Traversing Device
A configuration of the traversing device 22 will be explained below with reference to FIG. 3. FIG. 3 is an enlarged view of the traversing device 22 and a peripheral configuration thereof.
The traversing device 22 is, for example, a so-called arm traversing-type device. The traversing device 22 includes an arm 31 that can reciprocate in a direction that is substantially parallel to the bobbin axis direction, the traverse guide 32 that is mounted on a tip of the arm 31, and a traverse motor 33 ("traverse driving section" according to the present invention) that drives the arm 31 to swing. The traverse motor 33 includes, for example, a sensor 34 as a detecting section that detects the angular velocity of the rotor of the traverse motor 33. The traverse motor 33 is electrically connected to the unit controller 30. When the unit controller 30 controls the traverse motor 33 and drives the arm 31 to swing, the traverse guide 32 travels reciprocally in a direction that is substantially parallel to the bobbin axis direction (see an arrow in FIG. 3). Hereinafter, the direction in which the traverse guide 32 reciprocates will be referred to as a traverse direction.
The traversing device 22 can be, for example, a so-called belt traverse-type device that includes a not-shown pulley and an endless belt to which the traverse guide 32 is attached. In other words, the traversing device 22 can be controllable independently of the package driving motor 41.
Motor Control and Calculation of Package Diameter by Unit Controller
The unit controller 30 acquires information on the traveling speed (traversing speed) of the traverse guide 32, based on a detection result obtained in the sensor 34. The unit controller 30 generates a speed pattern (details will be explained later) that indicates information relating to a target value of the traversing speed. The unit controller 30 controls the traverse motor 33 such that the actual traversing speed matches the speed pattern.
The unit controller 30 controls the package driving motor 41 to rotate the package P and controls the traverse motor 33 to reciprocate the traverse guide 32. Accordingly, the yarn Y is wound in an inclined state with respect to the surface (circumferential surface) of the package P. The angle (traverse angle) formed between the circumferential surface of the package P and the yarn Y wound on the package P is determined based on the relation between the circumferential speed (winding speed) and the traversing speed of the package P. Generally, assuming that the traverse angle is ?, the traversing speed is v, and the winding speed is u, the relation of tan ? ? v / u holds true. In other words, the traverse angle becomes larger if the traversing speed is faster than the winding speed, and the traverse angle becomes smaller if the traversing speed is slower than the winding speed. Generally, when the traverse angle is large, the density (winding density) of the package P is low, and when the traverse angle is small, the winding density is high.
The unit controller 30 detects the diameter of the package P based on the traveling speed of the yarn Y traveling on a yarn traveling path between the yarn supplying bobbin Bs and the contact roller 23. Specifically, the traveling speed of the yarn Y is detected by the yarn clearer 25 or a dedicated yarn speed sensor. The traverse angle is calculated in the unit controller 30 based on the traveling speed and the traversing speed of the yarn Y, and the circumferential speed of the package P is calculated based on the traverse angle and the traveling speed. Therefore, the diameter of the package P can be calculated based on the rotational speed of the package P and the circumferential speed of the package P.
However, the unit controller 30 can calculate the diameter of the package P by using another method. For example, the unit controller 30 can calculate the diameter of the package P by using the rotational speed of the package P detected by the sensor 42 and the rotational speed of the contact roller 23 detected by the sensor 43. First, the unit controller 30 calculates the circumferential speed of the contact roller 23 (that is, the circumferential speed of the package P) based on the detected rotational speed of the contact roller 23 and information on the diameter of the contact roller 23 that is set beforehand. Then, the unit controller 30 calculates the diameter of the package P based on the rotational speed of the package P and the circumferential speed of the package P. The diameter of the package P can be calculated in this manner.
Setting Section
The target value of the traverse angle explained above can be set by using the setting section 4 of the main control device 3. The setting section 4 is explained below with reference to FIG. 4. As shown in FIG. 4, the display panel 4a displays names of the winding conditions (control mode, reference traverse angle, end portion traverse angle, and the like) that can be set (see portions enclosed in thin blocks in FIG. 4). On the display panel 4a, specific conditions are displayed next to the names of the winding conditions (see portions enclosed in thick blocks in FIG. 4). The setting section 4 is configured such that the operator can set the winding conditions and the like by operating the operation panel 4b.
In the present embodiment, the "Control Mode" refers to a mode relating to operation control of the traverse guide 32 performed by the unit controller 30. The setting section 4, for example, selects a control mode called "Constant End Portion" mode (details will be explained later) as shown in FIG. 4. The main control device 3 transmits to the unit controller 30 of each winding unit 2 the information relating to the control mode. The unit controller 30 acquires a later explained speed pattern based on that information relating to the control mode.
The "Reference Traverse Angle" is a target value of the traverse angle during one reciprocation of the traverse guide 32 (that is, a target average value of the traverse angle formed in the entire region across which the traverse guide 32 reciprocates in the traverse direction). For example, in FIG. 4, as shown in the upper portion of the display panel 4a, the value of the reference traverse angle is set to 20 degrees. In the present embodiment, the value "20 degrees" is the initial value of the reference traverse angle during the winding process. The main control device 3 transmits to the unit controller 30 of each winding unit 2 the information relating to the reference traverse angle. The unit controller 30 mainly acquires a speed pattern to be used at the central portion in the traverse direction (central portion speed pattern) based on the reference traverse angle information and an end portion speed pattern in the traverse direction explained later. The details are explained later.
The "End Portion Traverse Angle" is the target value of the traverse angle at the end portion of the package P in the bobbin axial direction. The end portion traverse angle at the left end portion and the end portion traverse angle at the right end portion of the package P can be set individually. For example, as shown in FIG. 4, a value of the end portion traverse angle is set to 22 degrees for left and right end portions. Of course, these values can be different from each other; however, in the present embodiment, the end portion traverse angles are assumed to be equal on the left and right sides to simplify the explanation. In the present embodiment, "22 degrees" is the initial value of the end portion traverse angle during the winding process. In this manner, the setting section 4 independently sets the initial value of the reference traverse angle and the initial value of the end portion traverse angle. The main control device 3 transmits to the unit controller 30 of each winding unit 2 the information relating to the end portion traverse angle. The unit controller 30 acquires a speed pattern at the end portion (end portion speed pattern) in the traverse direction based on the information of the end portion traverse angle. The details are explained later.
Furthermore, the setting section 4 can perform settings for changing the reference traverse angle during the yarn winding process. As a specific example, "Traverse Angle Adjustment" is displayed on the lower side of the display panel 4a in FIG. 4. Moreover, "Yarn Layer Thickness" and "Reference Traverse Angle" are displayed below "Traverse Angle Adjustment". The thickness of the yarn layer (Yarn Layer 1, Yarn Layer 2, Yarn Layer 3, and the like) and the reference traverse angle (Traverse angle 1, Traverse angle 2, Traverse angle 3, and the like) can be set by the operator by operating the operation panel 4b. For example, "Yarn Layer 1" is set to 15 millimeters (mm), and "Traverse Angle 1" is set to 19 degrees. This information, for example, is information necessary for the unit controller 30 to control the traverse motor 33 and the like such that the reference traverse angle is 19 degrees when the thickness of the yarn layer wound on the package P is 15 mm during the winding process. The details are explained later.
Speed Pattern
The speed pattern of the traverse guide 32 acquired by the unit controller 30 will be explained below. The speed pattern is the information that indicates a relation between a target value of the traversing speed (target traversing speed) and time. The unit controller 30 controls the traverse motor 33 based on the speed pattern. The unit controller 30 acquires the speed pattern based on the information such as the control mode, the reference traverse angle, the end portion traverse angle, and the like. The unit controller 30 generates and stores the speed pattern, for example, in the form of a table in which the target traversing speed and time are associated. The unit controller 30 generates, for example, this table by calculating the target traversing speed based on a predetermined calculation formula.
An example of the speed pattern of the traverse guide 32 is shown in FIG. 5. FIG. 5 is a graph showing a speed pattern used for one reciprocation of the traverse guide 32. The horizontal axis indicates time, and the vertical axis indicates the target traversing speed. In the left half of the graph is shown a speed pattern corresponding to when the traverse guide 32 moves from an end on the one side to an end on other side in the traverse direction is shown. In the right half of the graph is shown a speed pattern corresponding to when the traverse guide 32 moves from the end on the other side to the end on the one side in the traverse direction is shown.
The unit controller 30 acquires the end portion speed pattern, which is a speed pattern for an end portion in the traverse direction (see the parts shown in a thick line in FIG. 5) and the central portion speed pattern, which is a speed pattern for a portion other than the end portion (that is, the central portion) (see the parts shown in a thin line in FIG. 5). Specific examples will be explained below.
The unit controller 30 divides a movement area (traverse area) in which the traverse guide 32 can move in the traverse direction into the central portion and the end portions that are other than the central portion. Moreover, the unit controller 30 divides the time required for the traverse guide 32 to travel to the end portion (for example, the time duration between -t2 and t2 shown in FIG. 5) into an end portion movement time during which the traversing speed is kept constant and a reversal time during which the traverse guide 32 travels in a reverse direction. The end portion movement time is, for example, time duration between t1 and t2 shown in FIG. 5. The reversal time is, for example, time duration between -t1 and t1 shown in FIG. 5. The unit controller 30 determines the target speed of the traverse guide 32 (v1 in FIG. 5) during the end portion movement time based on the end portion traverse angle, the circumferential speed of the package P, and the reversal time. The reversal time is set beforehand. Moreover, the unit controller 30 generates a speed pattern of the traverse guide 32 during the reversal time (that is, a speed pattern for changing the traversing speed from -v1 to +v1 shown in FIG. 5). Furthermore, the movement distance of the traverse guide 32 during the end portion movement time is determined based on an end portion movement length set beforehand or based on the product of the end portion movement time and the target speed v1. The movement distance that the traverse guide 32 travels during the reversal time is appropriately determined by considering the length of the end portions of the traverse area and the like. In this manner, the unit controller 30 acquires the end portion speed pattern.
Moreover, the unit controller 30 divides the time taken by the traverse guide 32 to travel to central portion (for example, time duration between t2 and t5 shown in FIG. 5) into a speed changing time required for changing the traversing speed and a central portion movement time. The speed changing time is, for example, time duration between t2 and t3 and time duration between t4 and t5 shown in FIG. 5. The central portion movement time is, for example, time duration between t3 and t4 shown in FIG. 5. The unit controller 30 calculates the central portion movement time based on the reversal time, the end portion movement time, and the speed changing time that is set beforehand, and determines the target speed (v2 in FIG. 5) of the traverse guide 32 based on the length of the central portion movement time calculated from the target traversing speed that is calculated based on the central portion movement time, the information relating to the reference traverse angle, and the circumferential speed of the package P explained above. Moreover, the unit controller 30 generates a speed pattern of the traverse guide 32 during the speed changing time (that is, a speed pattern for changing the traversing speed from the target speeds v1 to v2 in FIG. 5). Furthermore, the movement distance of the traverse guide 32 during the speed changing time is determined based on the target speed v1 and the speed changing time set beforehand. Accordingly, the unit controller 30 acquires the central portion speed pattern.
The speed pattern of the entire area in the traverse direction can be acquired by combining the end portion speed pattern and the central portion speed pattern obtained in such a manner. The length of the region shown in the graph of FIG. 5 (that is, the time integral of the speed) is the length of the traverse region (traverse width). The speed pattern is generated such that the time integral of the traversing speed is equal to the set value of a predetermined traverse width.
As explained above, by setting different traversing speeds for the central portion and the end portions in the traverse direction, it is possible to set different traverse angles for the central portion and the end portions in the bobbin axial direction of the package P. Accordingly, for example, by increasing the end portion traverse angle and the traversing speed at the end portions in the traverse direction, the staying time period of the yarn Y at the end portion in the bobbin axial direction of the package P can be shortened, and occurrence of cob-webbing can be suppressed.
Step Precision Winding
Next, the step precision winding, which is one of the types of the yarn winding, will be explained with reference to FIG. 6. FIG. 6 is a graph showing the relation between the diameter of the package P and the actual traverse angle during the step precision winding. Note that, to simplify the explanation, the set value of the reference traverse angle is assumed to be constant.
The step precision winding is a type of yarn winding in which a winding ratio, which is a ratio of the number of rotations of the package P per unit time to the number of reciprocations of the traverse guide 32 per unit time, is changed in stepped manner. The step precision winding is performed to maintain the traverse angle at a value that is close to that of the reference traverse angle while suppressing the winding ratio from becoming the so-called dangerous winding ratio (a winding ratio in which "ribbon winding" occurs in which the yarn is repeatedly wound at the same location onto the surface of the package P). During the step precision winding, the actual traverse angle is changes with time from the reference traverse angle as shown in FIG. 6.
Specifically, the unit controller 30 of each winding unit 2 performs the step precision winding as explained below. Immediately after the start of the yarn winding process, the unit controller 30 acquires the speed pattern of the traverse guide 32 such that the actual traverse angle is larger than the reference traverse angle, and then winds the yarn Y around the winding bobbin Bw while maintaining a constant winding ratio. The unit controller 30 decreases the traversing speed to maintain the winding ratio at a constant value in accordance with the increase in the diameter of the package P (that is, decreases the number of rotations of the package P per unit time to keep the circumferential speed of the package P at a constant value). Accordingly, the actual traverse angle becomes smaller as the diameter of the package P increases (the winding becomes thicker) and approaches the value of the reference traverse angle. When the actual traverse angle reaches a value little higher than the reference traverse angle, the unit controller 30 changes the winding ratio (decreases the winding ratio) in a stepped manner by changing the traversing speed to avoid the dangerous winding ratio. Then, the unit controller 30 maintains the winding ratio at a constant value again and changes the winding ratio again for the next step after the actual traverse angle has reaches a value little higher that the reference traverse angle. The step precision winding is performed by repeating this operation.
Traverse Angle Adjustment and Control Mode
In the explanation of the step precision winding, the reference traverse angle is assumed to be constant. If the reference traverse angle is actively changed, the following problems can occur. First, referring again to FIG. 4, "Traverse Angle Adjustment" and "Control Mode" will be explained in more detail. As explained above, generally, as the traverse angle becomes larger, the winding density becomes low, and as the traverse angle becomes smaller, the winding density becomes high. Therefore, to obtain a package P having a desired winding density, the setting section 4 performs settings for actively changing the reference traverse angle in accordance with the change in the thickness of the yarn layer (thickening of the winding) (that is, adjustment of the traverse angle). As a specific example, as shown in FIG. 4, the settings are performed such that when the thickness of the yarn layer is 15 mm, the reference traverse angle is set to 19 degrees; when the thickness of the yarn layer is 30 mm, the reference angle is set to 18 degrees; and when the thickness of the yarn layer is 45 mm, the reference angle is set to 17 degrees. The unit controller 30 of the winding unit 2 changes the reference traverse angle from the initial value (20 degrees) during the yarn winding process, based on the setting operation explained above. Aspects of change in the reference traverse angle can be set in any manner. For example, the reference traverse angle can be changed gradually according to the change in the thickness of the yarn layer by using a predetermined calculation formula (see FIG. 7A), based on the set values for "Traverse Angle Adjustment" shown in FIG. 4. Alternatively, the reference traverse angle can be changed in a stepped manner (see FIG. 7B).
The control modes are explained below. The "Constant End Portion" mode shown in FIG. 4 is a mode in which the end portion traverse angle is kept constant regardless of the change in the reference traverse angle as explained above. Accordingly, because the end portion speed pattern is constant, occurrence of unevenness (so-called "step winding") on the end surface of the package P is suppressed.
Here, problems that occurs when the control mode is set to the constant end portion mode will be explained with reference to FIGS. 7A, 7B, 8A, and 8B. FIGS. 7A and 7B are graphs showing the relation between the reference traverse angle, the end portion traverse angle, and the diameter of the package P (thickness of the yarn layer) when the end portion traverse angle is kept constant. FIG. 8A is a graph showing two speed patterns in which the end portion traverse angles are set to the same value, but the reference traverse angles are set to different values. FIG. 8B is an explanatory diagram showing a change in the shape of the package P when the end portion traverse angle is kept constant.
When the control mode is set to the constant end portion mode, the end portion traverse angle is maintained at a constant value (see FIGS. 7A and 7B) while the reference traverse angle is decreased in accordance with the winding thickness of the package P. In such a case, for example, a speed pattern assuming that the reference traverse angle is ?1 and a speed pattern assuming that the reference traverse angle is ?2, which is smaller than ?1, are as shown in FIG. 8A. In other words, when the reference traverse angle is smaller, the difference increases between the target traversing speed during the central portion movement time and the target traversing speed during the end portion movement time. When such difference increases, in the bobbin axial direction, the difference between the winding density in the central portion of the package P and the winding density at the end portions of the package P becomes significantly large, and as shown in FIG. 8B, the shape of the package P can deteriorate due to the increase in the winding thickness of the package P. To solve such a problem, the automatic winder 1 is configured to suppress the significant difference in the traverse angle between the central portion and the end portions of the package P.
Setting Section
First, the setting section 4 according to the present embodiment will be explained with reference to FIG. 9. The setting section 4 is capable of changing the control mode explained above. In other words, the setting section 4 performs operations to change the control modes between the "Constant End Portion" mode (see FIG. 4) and the "End Portion Interlinking" mode shown in FIG. 9. In other words, the setting section 4 can select either the constant end portion mode or the end portion interlinking mode. The operator can change the control mode between the constant end portion mode and the end portion interlinking mode by operating the operation panel 4b. When the control mode is set to the end portion interlinking mode, for example, the main control device 3 calculates the difference between the set value of the reference traverse angle (20 degrees) and the set value of the end portion traverse angle (22 degrees), and transmits the calculated difference to the unit controller 30. In other words, the main control device 3 transmits to the unit controller 30 information that indicates that the difference between the end portion traverse angle and the reference traverse angle is 2 degrees. Alternatively, this difference can be calculated by the unit controller 30. The unit controller 30 that receives the information from the setting section 4 performs the interlinking control during the yarn winding process as explained below.
Interlinking Control
The yarn winding method according to the present embodiment (particularly, the interlinking control performed by the unit controller 30) will be explained with reference to FIGS. 10A, 10B, and 11. FIG. 10A is a graph showing change in the reference traverse angle and change in the end portion traverse angle when the reference traverse angle is decreased during the yarn winding process. FIG. 10B is a graph showing change in the reference traverse angle and change in the end portion traverse angle when the reference traverse angle is increased during the yarn winding process. FIG. 11 is a graph showing a speed pattern used when the control mode is set to the interlinking mode. Furthermore, to simplify the explanation, in the present embodiment, the unit controller 30 changes the reference traverse angle gradually (continuously). In other words, the unit controller 30 changes the reference traverse angle gradually in accordance with the change in the thickness of the yarn layer (see FIG. 9) by using a predetermined calculation formula. However, the configuration is not limited thereto.
The unit controller 30 changes the reference traverse angle from the initial value during the yarn winding process (for example, during the step precision winding). Moreover, the unit controller 30 performs the interlinking control in which the end portion traverse angle is changed in accordance with the change in the reference traverse angle. As the interlinking control, the unit controller 30 decreases the end portion traverse angle when decreasing the reference traverse angle (see FIG. 10A). In contrast, the unit controller 30 increases the end portion traverse angle when increasing the reference traverse angle (see FIG. 10B). In the interlinking control, the unit controller 30 maintains, for example, the difference between the end portion traverse angle and the reference traverse angle at a constant value (2 degrees in the present embodiment). Accordingly, as shown in FIG. 11, even if the reference traverse angle changes, the increase in the difference between the traversing speed during the central portion movement time and the traversing speed during the end portion movement time is suppressed.
Control Performed when Reversing Traverse Guide
Next, a reversal control of the traverse guide 32 performed by the unit controller 30 will be explained below with reference to FIG. 12. FIG. 12 is a graph showing the speed pattern used for the end portion in the traverse direction. Particularly, the traversing speed during the reversal time (see FIG. 5) explained above will be explained below.
First, during the end portion movement time, a state in which the traverse guide 32 travels outward in the traverse direction at a constant speed (end portion speed; the end portion speed is equivalent to "predetermined speed" according to the present invention) is assumed. For example, as shown in FIG. 12, when the end portion traverse angle is ?a, the end portion speed is va. In this state, the unit controller 30 performs the reversal control as explained below. In other words, the unit controller 30 controls the traverse motor 33 to cause the traverse guide 32 that is traveling outward in the traverse direction at the end portion speed (that is, traveling at the speed -va) to decelerate and reverse to travel inwardly. Then, the unit controller 30 causes the traverse guide 32 to re-accelerate to the end portion speed (that is, to the speed +va). In the present embodiment, the magnitude of the deceleration and the acceleration of the traverse guide 32 are assumed to be constant. For example, if the time required to change the traversing speed from zero to +va is considered as ta, the acceleration is va/ta.
In this control, the unit controller 30 sets the length in the traverse direction of the area (reversal area) in which the traverse guide 32 moves from the time the traverse guide 32 is caused to decelerate till the completion of re-acceleration in the inverse control to a constant value regardless of the value of the end traverse angle. For example, when the end traverse angle is ?a, the length of the area that the traverse guide 32 travels across in the time duration between the change in the traversing speed from -va to +va is the length of the reversal area. When the magnitude of the deceleration and the acceleration is kept constant as explained above, the length of the reversal area is the value of the time integral of the traversing speed, that is, va × ta/2. Moreover, if the end portion speed when the end traverse angle is ?b is vb and the time required to change the traversing speed from zero to +vb is tb, the length of the reversal area is vb × tb/2. The unit controller 30 generates the end portion speed pattern such that the length of the reversal area remains constant regardless of the value of the end portion traverse angle (that is, such that va × ta = vb × tb). Accordingly, a change in the reversal start position of the yarn Y in the bobbin axis direction is suppressed. Therefore, disarrangement of the shape of the package P at the end portions in the bobbin axial direction is suppressed.
As explained above, when the reference traverse angle increases, the end portion traverse angle, too, increases, and when the reference traverse angle decreases, the end portion traverse angle, too, decreases. Accordingly, the increase in the difference between the reference traverse angle and the end portion traverse angle can be suppressed, compared to when the end portion traverse angle is maintained at a constant value. Therefore, it is possible to suppress the increase in the difference between the traverse angle at the central portion and the traverse angle at the end portions in the axial direction of the package P.
Moreover, the control mode can be switched between the interlinking mode, in which the interlinking control is performed, and the constant end portion traverse angle mode. Therefore, even when there is a need to perform the yarn winding process in the conventional constant end portion traverse angle mode, it can be easily performed by switching between the control modes.
Moreover, even during the step precision winding explained above, it is possible to suppress the increase in the difference between the reference traverse angle and the end portion traverse angle, compared to when the end portion traverse angle is set to a constant value.
The unit controller 30 sets the length of the reversal area to a constant value, regardless of the value of the end portion traverse angle. Accordingly, change in the start position of the reversal of the yarn Y during the yarn winding process is suppressed. Therefore, the disarrangement of the shape of the package P at the end portions of the package is suppressed.
Next, modifications made in the embodiments explained above will be explained. However, the structural elements having the same configuration as the embodiments explained above are denoted by the same reference numerals, and the explanation thereof is appropriately omitted.
(1) In the embodiments explained above, when the control mode is set to the end portion interlinking mode, the unit controller 30 maintains the difference between the reference traverse angle and the end portion traverse angle to a constant value. The present invention however is not limited to such a configuration. In other words, the difference between the reference traverse angle and the end portion traverse angle need not necessarily be maintained at a constant value.
(2) In the embodiments explained above, when the control mode is set to the end portion interlinking mode, the end portion traverse angle always increases when the reference traverse angle increases, and the end traverse angle always decreases when the reference traverse angle decreases; however, the present invention is not limited to such a configuration. The related modification is explained below with reference to FIGS. 13, 14A, and 14B. As shown in FIG. 13, the setting section 4 can set the maximum end portion traverse angle and the minimum end portion traverse angle when the control mode is set to the end portion interlinking mode. In this case, as shown in FIG. 14A, when the end portion traverse angle is equal to or larger than the minimum end portion traverse angle, the unit controller 30 decreases the end portion traverse angle by interlinking thereof with the decrease in the reference traverse angle. Moreover, in the event that the end portion traverse angle is likely to fall below the minimum end portion traverse angle, the unit controller 30 maintains the end portion traverse angle at the minimum end portion traverse angle (20 degrees in this modification). In other words, the unit controller 30 can perform a control such that the end portion traverse angle does not fall below the minimum end portion traverse angle. With such a configuration, the traversing speed of the traverse guide 32 at the end portion in the traverse direction can be prevented from becoming too slow. Consequently, an occurrence of cob-webbing can be suppressed. Moreover, as shown in FIG. 14B, when the end portion traverse angle is equal to or smaller than the maximum end portion traverse angle, the unit controller 30 increases the end portion traverse angle by interlinking thereof with the increase in the reference traverse angle. Moreover, when the end portion traverse angle is likely to exceed the maximum end portion traverse angle, the unit controller 30 maintains the end portion traverse angle at the maximum end portion traverse angle (24 degrees in the present modification). In other words, the unit controller 30 can perform control such that the end portion traverse angle does not exceed the maximum end portion traverse angle. With such a configuration, the traversing speed of the traverse guide 32 at the end portion in the traverse direction can be prevented from becoming too fast. Consequently, an increase in a load on the traverse motor 33 (see FIG. 3) can be suppressed.
(3) In the embodiments explained above, the unit controller 30 maintains the length of the reversal area at a constant value, regardless of the value of the end portion traverse angle. However, in such a configuration, when the end portion speed is fast, it is necessary to cause the traverse guide 32 to accelerate rapidly in a short time. Therefore, the increase in the load on the traverse motor 33 becomes a concern. To solve such a problem, the unit controller 30 can perform the following control. As shown in FIG. 15, assuming that the end portion speed when the end portion traverse angle is ?a is va, and the time required to change the traversing speed from zero to +va is ta. In this case, the acceleration of the traverse guide 32 is va/ta. Moreover, assuming that the end portion speed when the end portion traverse angle is ?b is vb, and the time required to change the traversing speed from zero to +vb is tb. In this case, the acceleration of the traverse guide 32 is vb/tb. The unit controller 30 can set the acceleration to be constant when the traverse guide 32 is traveling in the reverse direction, regardless of the value of the end portion traverse angle. In other words, va/ta = vb/tb can be set. With such a configuration, the increase in the load on the traverse motor 33 can be suppressed.
(4) In the embodiments explained above, when the control mode is set to the interlinking mode, the unit controller 30 gradually changes the reference traverse angle and the end portion traverse angle according to the change in the thickness of the yarn layer by using a predetermined calculation formula. The present invention however is not limited to such a configuration. For example, the unit controller 30 can change the reference traverse angle and the end portion traverse angle in a stepped manner.
(5) In the embodiments explained above, the unit controller 30 performs the interlinking control during the step precision winding; however, the present invention is not limited such a configuration. When the reference traverse angle is changed during the yarn winding process, regardless of the yarn winding method, changing the end portion traverse angle by interlinking thereof with the reference traverse angle is effective.
(6) In the embodiments explained above, the setting section 4 selects either the end portion interlinking mode or the constant end portion mode; however, the present invention is not limited to such a configuration. In other words, the setting section 4 can select a control mode that is different from the end portion interlinking mode and the constant end portion mode. Alternatively, the setting section 4 can only set the end portion interlinking mode.
(7) In the embodiments explained above, the setting section 4 is provided in the main control device 3; however, the present invention is not limited to such a configuration. The setting section 4, for example, can be provided in each winding unit 2.
(8) In the present embodiment explained above, the unit controller 30 causes the winding unit 2 to perform the yarn winding process. The present invention however is not limited to such a configuration. For example, instead of the unit controller 30, the main control device 3 can control each winding units 2.
(9) In the embodiments explained above, the setting section 4 sets the thickness of the yarn layer and the reference traverse angle associated thereof to change the reference traverse angle during the yarn winding process; however, the present invention is not limited to such a configuration. In other words, the setting section 4 can only set the initial value of the reference traverse angle and the initial value of the end portion traverse angle. In such a configuration, for example, the unit controller 30 can gradually change the reference traverse angle during the yarn winding process based on the predetermined calculation formula.
(10) When the control mode is set to the end portion interlinking mode, the setting section 4 can display on the display panel 4a the value of the end portion traverse angle associated with the thickness of the yarn layer and the reference traverse angle.
(11) In the embodiments explained above, the setting section 4 individually sets the end portion traverse angle at a left end portion and the end portion traverse angle at a right end portion of the package P; however, the present invention is not limited to such a configuration. In other words, the setting section 4 can set the end portion traverse angle that is common for the left end portion and the right end portion.
(12) In the embodiments explained above, the setting section 4 sets the end portion traverse angle and the like; however, the present invention is not limited to such a configuration. For example, the setting section 4 can set the difference between the initial value of the reference traverse angle and the initial value of the end portion traverse angle. As a specific example, when it is desired to set the initial value of the end portion traverse angle to be 2 degrees higher than the initial value of the reference traverse angle, the setting section 4 can be configured such that "+2 degrees" can be input as the difference between the end portion traverse angle and the reference traverse angle. Similarly, in the embodiments explained above, the setting section 4 sets the traverse angle for adjusting the traverse angle (Traverse Angle 1, Traverse Angle 2, Traverse Angle 3, and the like explained above) to change the reference traverse angle during the winding process; however, the present invention is not limited to such a configuration. For example, the setting section 4 can set the difference between the initial value of the reference traverse angle and the traverse angle for adjusting the traverse angle.
(13) The present invention is not limited to the automatic winder 1 and can be applicable to various yarn winding machines such as a spinning machine for spinning yarn.
According to one aspect of the present invention, a yarn winding machine that performs yarn winding process in which a package is formed while traversing a yarn and winding the yarn onto a bobbin includes a traverse guide that causes the yarn to traverse; a traverse driving section that reciprocally drives the traverse guide in a predetermined traverse direction; a setting section that independently sets, as target values of a traverse angle, at least an initial value of a reference traverse angle and an initial value of the traverse angle that is different from the reference traverse angle, the traverse angle being an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package, and is an angle formed between a plane perpendicular to the longitudinal central axis of the package and the yarn that is being traversed; and a controlling section. The controlling section acquires, based on information indicating an end portion traverse angle, an end portion speed pattern that is a speed pattern of the traverse guide at an end portion in the traverse direction; acquires, based on information indicating the end portion speed pattern and the reference traverse angle, a central portion speed pattern that is a speed pattern of the traverse guide at the central portion in the traverse direction; controls the traverse driving section based on the central portion speed pattern and the end portion speed pattern; and performs, by changing the reference traverse angle from the initial value during the yarn winding process, an interlinking control in which the end portion traverse angle is increased when the reference traverse angle is increased, and the end portion traverse angle is decreased when the reference traverse angle is decreased.
In the above aspect, at least the initial value of the reference traverse angle and the initial value of the end portion traverse angle can be set independently. Furthermore, during the yarn winding process, an interlinking control in which the reference traverse angle is changed from the initial value and the end portion traverse angle is changed by interlinking thereof to change in the reference traverse angle. Specifically, the end portion traverse angle is increased when the reference traverse angle is increased, and the end portion traverse angle is decreased when the reference traverse angle is decreased. With such a configuration, increase in difference between the reference traverse angle and the end portion traverse angle can be suppressed, compared to when the end portion traverse angle is set to a constant value. Therefore, a significant difference between the traverse angle at the central portion and the traverse angle at the end portions of the package can be suppressed.
In the above aspect, the setting section performs an operation of switching a control mode of the controlling section between an interlinking mode in which the interlinking control is performed and a constant end portion traverse angle mode in which the end portion traverse angle is maintained at a constant value during the yarn winding process.
According to the above aspect, even when there is a need to perform the yarn winding process in the conventional constant end portion traverse angle mode, it can be easily performed by operating the setting section to switch between the control modes.
In the above aspect, the controlling section is capable of performing step precision winding in which a certain winding ratio, which is a ratio between number of rotations of the package per unit time and number of reciprocations of the traverse guide per unit time, is changed in a stepped manner as a diameter of the package increases during the yarn winding process, and the controlling section performs the interlinking control during the step precision winding.
During the step precision winding, the actual traverse angle changes with time even if the reference traverse angle is temporarily set to a constant value (details have been explained in the above embodiments). To address this issue, according to the above aspect, even during the step precision winding, increase in the difference between the reference traverse angle and the end portion traverse angle can be suppressed compared to when the end portion traverse angle is constant. Therefore, a significant difference between the traverse angle at the central portion and the traverse angle at the end portions of the package can be suppressed.
In the above aspect, the setting section sets a predetermined minimum end portion traverse angle, and the controlling section performs settings such that the end portion traverse angle does not decrease below the minimum end portion traverse angle during the interlinking control.
When the end portion traverse angle decreases, the traversing speed at the end portion in the traverse direction becomes relatively slow. If the traversing speed becomes too slow at the end portion in the traverse direction, the time during which the yarn stays near the package end surface becomes longer, and cob-webbing (a phenomenon in which the yarn slips off the package end surface) is likely to occur. According to the above aspect, because the end portion traverse angle is prevented from becoming smaller than the minimum end portion traverse angle during the interlinking control, the occurrence of the cob-webbing can be suppressed.
In the above aspect, the setting section sets a predetermined maximum end portion traverse angle, and the controlling section performs settings such that the end portion traverse angle does not exceed the maximum end portion traverse angle during the interlinking control.
When the end portion traverse angle increases, the traversing speed becomes relatively faster. If the traversing speed becomes too fast, there is a possibility that the load on the traverse driving section also becomes too significant. According to the above aspect, because the end portion traverse angle is prevented from becoming larger than the maximum end portion traverse angle during the interlinking control, increase in the load on the traverse driving section can be suppressed.
In the above aspect, the controlling section controls the traverse driving section to perform a reversal control in which the traverse guide that is traveling outward in the traverse direction at a predetermined speed is caused to decelerate, travel inwardly in a reverse direction, and re-accelerate up to the predetermined speed, and sets a length of a reversal area across which the traverse guide moves between start of deceleration of the traverse guide and end of the re-acceleration during the reversal control to a constant value regardless of a value of the end portion traverse angle.
According to the above aspect, because the length of the reversal area does not change regardless of the value of the end portion traverse angle, a change in the reversal start position of the yarn during the yarn winding process is suppressed. Therefore, disarrangement of the package shape at the end portions of the package can be suppressed.
In the above aspect, the controlling section controls the traverse driving section to perform a reversal control in which the traverse guide that is traveling outward in the traverse direction at a predetermined speed is caused to decelerate, travel inwardly in a reverse direction, and re-accelerate to the predetermined speed, and sets a magnitude of the deceleration and acceleration of the traverse guide between a start of deceleration of the traverse guide to an end of re-acceleration during the reversal control to a constant value regardless of a value of the end portion traverse angle.
As explained above, if the length of the reversal area does not change regardless of the value of the end portion traverse angle, when the end portion traverse angle is large (that is, when the traversing speed at the end portion in the traverse direction is large), rapid deceleration and rapid acceleration of the traverse guide become necessary. In such a case, there is a possibility that the load on the traverse driving section might increase. According to the above aspect, because the fluctuation in the deceleration and the acceleration is suppressed even when the end portion traverse angle increases, an increase in the load on the traverse driving section can be suppressed.
According to another aspect of the present invention, a yarn winding method for performing a yarn winding process in which a package is formed while traversing a traveling yarn in a predetermined direction by using a traverse guide and winding the yarn onto a rotating bobbin includes setting independently, as target values of a traverse angle, at least an initial value of a reference traverse angle and an initial value of the traverse angle that is different from the reference traverse angle, the traverse angle being an angle between the traversed yarn and a projection of the yarn on a plane that includes a longitudinal central axis of the package, and is an angle formed between a plane perpendicular to the longitudinal central axis of the package and the yarn that is being traversed; acquiring, based on information indicating the end portion traverse angle, an end portion speed pattern that is a speed pattern of the traverse guide at an end portion in the traverse direction; acquiring, based on information indicating the end portion speed pattern and the reference traverse angle, a central portion speed pattern that is a speed pattern of the traverse guide at a central portion in the traverse direction; causing the traverse guide to travel reciprocally based on the central portion speed pattern and the end portion speed pattern; and increasing the end portion traverse angle when the reference traverse angle is increased and decreasing the end portion traverse angle when the reference traverse angle is decreased by changing the reference traverse angle from an initial value thereof during the yarn winding process.
According to the above aspect, similar to the other aspects, the significant difference between the traverse angle at the central portion and the traverse angle at the end portions of the package can be suppressed during the yarn winding process.
In the above explanation, the meaning of "a plurality of" also includes "a predetermined number of".
Although the invention has been explained with respect to specific embodiments for a complete and clear disclosure, the appended claims are not to be thus limited but are to be construed as embodying all modifications and alternative constructions that may occur to one skilled in the art that fairly fall within the scope of the claims.