Patent Description:
<CIT> discloses a yarn winding device configured to wind a yarn onto a bobbin while traversing the yarn by a traverse guide, so as to form a package. The yarn winding device includes a bobbin driving motor configured to rotationally drive the bobbin, a guide driving mechanism configured to reciprocate the traverse guide by means of a guide driving motor, and a controller configured to control the bobbin driving motor and the guide driving motor. A way of winding a yarn by such a yarn winding device is precision winding in which the ratio of the number of rotations of the bobbin to the number of traversal per unit time (i.e., winding ratio) is controlled to be constant. In the precision winding, the winding ratio is typically arranged to be a value slightly different from an integer, in order to prevent the formation of a ribbon (i.e., to prevent the yarn from being repeatedly wound on the same path on the surface of the package). With this arrangement, in the precision winding, the formation of a ribbon is avoided and the yarn is regularly wound in a parallel manner, as the path of the yarn wound on the surface of the package is gradually shifted. As a result, the yarn is easily unwound from the completed package, and the density of the package is easily controlled in accordance with the use of the package.

Meanwhile, <CIT> discloses a traverse unit capable of performing creeping with which the formation of a saddle bag on a package is suppressed. The saddle bag is a problem that an amount of a yarn wound at an end portion of the surface of a package in the axial direction is larger than an amount of the yarn wound on other parts of the surface, because, for example, it is typically difficult to swiftly reverse (i.e., change the direction of) the traverse guide. The formation of a saddle bag may deteriorate the shape of the package and/or may cause the density of the package to be irregular. The creeping is an action to temporarily narrow the width (traverse width) of a reciprocal movement range of the traverse guide during the formation of the package. With this arrangement, the amount of the yarn wound at the end portion in the axial direction of the package is decreased as compared to cases where the creeping is not performed, with the result that the formation of the saddle bag is suppressed.

Other examples of the prior art, which disclose a yarn winding device according to the preamble of claim <NUM> and a yarn winding method according to the preamble of claim <NUM>, can be seen in documents <CIT>, <CIT>, and <CIT>.

When the creeping is performed during the precision winding in the yarn winding device of <CIT>, the following problem may occur. (The problem will be detailed in the embodiment below. ) For example, when the traverse width in the creeping is simply narrowed as compared to the traverse width in normal traversal (hereinafter, in the normal state), the traverse cycle becomes inconsistent and hence the winding ratio becomes inconsistent. On this account, on the surface of the package, the position where the yarn is actually wound is deviated from the desired position, with the result that the shape of the surface of the package is poor. In order to prevent the occurrence of this problem, it is necessary to perform the creeping without changing the traverse cycle. However, for example, if one tries to achieve a constant winding ratio by simply differentiating the traveling speed of the traverse guide between the normal state and the creeping state, the angle (helix angle) between the yarn and the surface of the package becomes disadvantageously different between the normal state and the creeping state. As a result, the shape of the surface of the package is poor.

An object of the present invention is to suppress a winding ratio from being changed and to suppress the shape of the surface of a package from being poor, even when creeping is performed during precision winding.

According to a first aspect of the invention, a yarn winding device is configured to form a package by winding a running yarn onto a rotating bobbin while the yarn is traversed by a traverse guide and performing precision winding in which a winding ratio which is a ratio of the rotation number of the bobbin to the number of times of reciprocal movement of the traverse guide per unit time to be constant, the yarn winding device comprising: a guide driving unit which is configured to reciprocate the traverse guide in a predetermined traverse direction and is able to change a reversal position of the traverse guide during a winding operation of winding the yarn; and a control unit, the control unit being capable of performing: first reversal control in which the guide driving unit is controlled so that the traverse guide running outward in the traverse direction at a predetermined speed is decelerated, the running direction of the traverse guide is reversed to inward at a predetermined first reversal position, and then the traverse guide is re-accelerated to the predetermined speed; and second reversal control in which the guide driving unit is controlled so that the traverse guide running outward in the traverse direction at the predetermined speed is decelerated, the running direction of the traverse guide is reversed to inward at a second reversal position which is on the inner side of the first reversal position, and then the traverse guide is re-accelerated to the predetermined speed, during the precision winding, as compared to a first reversal time which is between start of deceleration to completion of re-acceleration in the first reversal control, a second reversal time which is between start of deceleration of the traverse guide and completion of re-acceleration in the second reversal control being arranged to be long. The control unit is configured to arrange the maximum value of the acceleration in the second reversal time to be identical with the maximum value of the acceleration in the first reversal time and to stop the traverse guide at the second reversal position in the traverse direction for a predetermined time and then accelerate the traverse guide again.

As a preparation for properly perform the precision winding while performing the creeping, the winding ratio must be arranged to be identical between a case where the traverse guide is reversed at the first reversal position (hereinafter, this case may be referred to as a normal state) and a case where the traverse guide is reversed at the second reversal position (hereinafter, this case may be referred to as a creeping state). In order to arrange the winding ratio to be identical between the states, when, for example, the rotation number of the bobbin is constant, it is necessary to arrange the movement cycle of the traverse guide to be identical between the normal state and the creeping state in which the width of the movable range of the traverse guide is narrow as compared to the normal state.

In the aspect of the present invention, the second reversal time is longer than the first reversal time. As the reversal time in the creeping state is actively elongated, the movement cycle of the traverse guide is arranged to be long in the creeping state. This makes it possible to arrange the movement cycle of the traverse guide to be identical between the normal state and the creeping state. It is therefore possible to prevent the winding ratio from being varied.

In addition to the above, because the traverse cycle in the creeping state is adjustable by adjusting the second reversal time as described above, the running speed of the traverse guide is arranged to be identical between the normal state and the creeping state when the reversal is not performed. It is therefore possible to arrange the angles of the yarn wound onto the surface of the package to be identical. It is therefore possible to suppress the shape of the surface of the package from being poor.

As described above, it is possible to suppress the winding ratio from being changed and to suppress the shape of the surface of the package from being poor, even when the creeping is performed during the precision winding.

According to an example which is not part of the invention, the yarn winding device is arranged so that, in the second reversal control, the controller arranges the width of a region in which the traverse guide moves in the traverse direction during the second reversal time to be long as the distance between the first reversal position and the second reversal position is long in the traverse direction.

In order to suppress the shape of the surface of the package from being poor while suppressing a variation of the winding ratio, the second reversal time must be arranged to be long as the distance between the first reversal position and the second reversal position is long (i.e., as the traverse width is narrow in the creeping state). Provided that the width of a region where the traverse guide moves in the traverse direction during the second reversal time (hereinafter, a reversal region) is constant, the traverse guide is disadvantageously kept in a region in the vicinity of the second reversal position for a long time in the second reversal control, when the second reversal time is long. As a result, the yarn tends to be wound onto a narrow region on the surface of the package, in a concentrated manner. As a result, a level difference tends to be formed on the surface of the package, and hence an adverse effect such as yarn stitching of the yarn may occur on, for example, the shape of the package.

In this example, the reversal region is wide when the distance between the first reversal position and the second reversal position is long. In other words, when the second reversal time becomes long as the traverse width in the creeping state is narrowed, the region in which the traverse guide is movable in the second reversal control becomes wide. On this account, it is possible to avoid a problem that the traverse guide is left in a narrow region in the traverse direction for a long time. It is therefore possible to suppress the yarn from being wound onto a narrow region on the surface of the package in a concentrated manner.

According to a second aspect of the invention, the yarn winding device of the first aspect is arranged such that, in the second reversal control, the controller controls the guide driving unit so that the traverse guide is positioned at the second reversal position in the traverse direction when a time that is a half of the second reversal time elapses from the start of the deceleration of the traverse guide.

In the second reversal control, for example, the traverse guide may be rapidly decelerated and reach the second reversal position, and may be gently re-accelerated. In this case, however, the shape of the reversed portion of the yarn wound onto the surface of the package may be significantly different between a case where the traverse guide is decelerated and a case where the traverse guide is re-accelerated. On this account, the shape of the reversed portion of the yarn on the surface of the package may not be symmetrical, and the reversed portion may not be neatly shaped. According to the aspect of the present invention, the time from the start of the deceleration of the traverse guide to the arrival of the traverse guide at the second reversal position is arranged to be equal to the time from the departure of the traverse guide from the second reversal position to the completion of the re-acceleration of the traverse guide. On this account, the reversed portion of the yarn is shaped to be symmetrical about the central axis of the wound package. (In other words, the reversed portion is neatly formed in shape. ) It is therefore possible to suppress the shape of the reversed portion of the surface of the package from being poor.

According to a third aspect of the invention, the yarn winding device of the first or second aspect further includes a bobbin driving unit which is configured to rotationally drive the bobbin, the control unit including a storage unit which is configured to store information of the relationship between a rotational angle of the bobbin and a position in the traverse direction of the traverse guide, and the bobbin driving unit and the guide driving unit being controlled based on the information stored in the storage unit.

In the aspect of the present invention, control is performed based on information of the relationship between the rotational angle of the bobbin and the position of the traverse guide. This makes it possible to simplify the complicated operation of performing the creeping while maintaining the winding ratio to be constant, as compared to, for example, control utilizing a complicated mechanical structure. Furthermore, it is possible to easily adjust the position and/or speed, etc. of the traverse guide in the second reversal control by rewriting the information.

According to a fourth aspect of the invention, the yarn winding device of any one of the first to third aspects is arranged so that the guide driving unit includes a driving source capable of driving forward and reverse.

For example, in a typical cam-type traverse unit, a motor configured to rotate in one direction is employed as a driving source, and a structure for performing creeping is a complicated mechanical structure. For this reason, it is difficult to finely control the creeping in the cam-type traverse unit. According to the aspect of the present invention, it is possible to cause the traverse guide to reciprocate by driving the driving source forward and backward. For this reason, the position and timing of the reversal of the traverse guide, etc. can be finely controlled by the controller. Fine control of the creeping can therefore be easily done.

According to a fifth aspect of the invention, the yarn winding device of the fourth aspect is arranged so that the guide driving unit includes a belt member to which the traverse guide is attached, the belt member being reciprocally driven by the driving source.

For example, in an arrangement in which a traverse guide is attached to a leading end portion of a swingable arm and the arm is driven in a swinging manner, the traverse guide reciprocates to draw an arc. On this account, it may be difficult to regularly wind the yarn onto the surface of the package even if the precision winding is performed. According to the aspect of the present invention, as the part of the belt member to which the traverse guide is attached is tensioned to be linear and is reciprocated, the traverse guide is easily reciprocated linearly. Regular winding of the yarn onto the surface of the package is therefore facilitated.

According to a sixth aspect of the invention, a yarn winding method is a method for forming a package by winding a running yarn onto a rotating bobbin while the yarn is traversed by a traverse guide and performing precision winding in which a winding ratio which is a ratio of the rotation number of the bobbin to the number of times of reciprocal movement of the traverse guide per unit time to be constant, the yarn winding method comprising: a first reversal step in which the traverse guide running outward in a predetermined traverse direction at a predetermined speed is decelerated, the running direction of the traverse guide is reversed to inward at a predetermined first reversal position, and then the traverse guide is re-accelerated to the predetermined speed; and a second reversal step in which the traverse guide running outward in the traverse direction at the predetermined speed is decelerated, the running direction of the traverse guide is reversed to inward at a second reversal position which is on the inner side of the first reversal position, and then the traverse guide is re-accelerated to the predetermined speed, during the precision winding, as compared to a first reversal time which is between start of deceleration to completion of re-acceleration in the first reversal step, a second reversal time which is between start of deceleration of the traverse guide and completion of re-acceleration in the second reversal step being arranged to be long. The maximum value of the acceleration in the second reversal time is identical with the maximum value of the acceleration in the first reversal time and the traverse guide is stopped at the second reversal position in the traverse direction for a predetermined time and then accelerate the traverse guide again.

According to this aspect, being similar to the first aspect, it is possible to suppress the winding ratio from being changed and to suppress the shape of the surface of the package from being poor, even when the creeping is performed during the precision winding.

The following will describe an example with reference to <FIG>. An up-down direction and a left-right direction shown in <FIG> will be used as an up-down direction and a left-right direction of a re-winder <NUM>. A direction orthogonal to both the up-down direction and the left-right direction (i.e., a direction perpendicular to the plane of <FIG>) is set as a front-rear direction. A direction in which a yarn Y runs will be referred to as a yarn running direction.

To begin with, the structure of a re-winder <NUM> (yarn winding device of the present invention) of the present embodiment will be described with reference to <FIG> is a schematic front view of the re-winder <NUM>. As shown in <FIG>, the re-winder <NUM> includes members such as a yarn supplying unit <NUM>, a winding unit <NUM>, a controller <NUM> (control unit of the present invention). The re-winder <NUM> is configured to unwind a yarn Y from a yarn supply package Ps supported by the yarn supplying unit <NUM>, re-wind the yarn Y back to a winding bobbin Bw (a bobbin of the present invention) by the winding unit <NUM>, so as to form a wound package Pw (a package of the present invention). To be more specific, the re-winder <NUM> is used for, for example, re-winding a yarn Y wound on a yarn supply package Ps in a more beautiful manner, and for forming a wound package Pw with desired density.

The yarn supplying unit <NUM> is, for example, attached to a front surface of a lower portion of a base <NUM> which vertically extends. The yarn supplying unit <NUM> is arranged to support the yarn supply package Ps which is formed by winding the yarn Y onto a yarn supplying bobbin Bs. The yarn supplying unit <NUM> is therefore able to supply the yarn Y.

The winding unit <NUM> is configured to form the wound package Pw by winding the yarn Y onto the winding bobbin Bw. The winding unit <NUM> is provided at an upper portion of the base <NUM>. The winding unit <NUM> includes members such as a cradle arm <NUM>, a winding motor <NUM> (a bobbin driving unit of the present invention), a traverse unit <NUM>, and a contact roller <NUM>.

The cradle arm <NUM> is, for example, supported by the base <NUM> to be swingable. The cradle arm <NUM> supports the winding bobbin Bw to be rotatable in such a way that, for example, the left-right direction is the axial direction of the winding bobbin Bw. At a leading end portion of the cradle arm <NUM>, a bobbin holder (not illustrated) is rotatably attached to hold the winding bobbin Bw. The winding motor <NUM> is configured to rotationally drive the bobbin holder. The winding motor <NUM> is, for example, a typical AC motor in which the rotation number is variable. The winding motor <NUM> is therefore able to change the rotation speed of the winding bobbin Bw. The winding motor <NUM> is electrically connected to the controller <NUM> (see <FIG>).

The traverse unit <NUM> is configured to traverse the yarn Y in the axial direction of the winding bobbin Bw (the left-right direction in the present embodiment). The traverse unit <NUM> is provided immediately upstream of the wound package Pw in the yarn running direction. The traverse unit <NUM> includes a traverse motor <NUM> (a guide driving unit of the present invention), an endless belt <NUM> (a belt member of the present invention), and a traverse guide <NUM>.

The traverse motor <NUM> is, for example, a typical AC motor. The traverse motor <NUM> is a driving source configured to be able to rotate forward and backward and is arranged so that the rotation number is variable. The traverse motor <NUM> is electrically connected to the controller <NUM> (see <FIG>). The endless belt <NUM> is a belt member to which the traverse guide <NUM> is attached. The endless belt <NUM> is wound onto pulleys <NUM> and <NUM> which are separated from each other in the left-right direction and a driving pulley <NUM> connected to the rotational shaft of the traverse motor <NUM>, and is substantially triangular in shape when wound onto the pulleys. The endless belt <NUM> is reciprocally driven by the traverse motor <NUM>. The traverse guide <NUM> is attached to the endless belt <NUM> and is provided between the pulley <NUM> and the pulley <NUM> in the left-right direction. The traverse guide <NUM> linearly and reciprocally runs in the left-right direction as the endless belt <NUM> is reciprocally driven by the traverse motor <NUM> (see arrows in <FIG>). As a result, the traverse guide <NUM> traverses the yarn Y in the left-right direction. Hereinafter, the left-right direction may be referred to as a traverse direction. In the traverse unit <NUM> arranged as described above, the width (traverse width) of the movable range of the traverse guide <NUM> during a winding operation of winding the yarn Y is changeable by controlling, for example, a timing to switch the rotational direction of the rotational shaft of the traverse motor <NUM>.

The contact roller <NUM> makes contact with the surface of the wound package Pw to adjust the shape of the wound package Pw by applying a contact pressure to the surface. The contact roller <NUM> makes contact with the wound package Pw and is rotated by the rotation of the wound package Pw.

Between the yarn supplying unit <NUM> and the winding unit <NUM>, a yarn guide <NUM>, a guide roller <NUM>, and a tension sensor <NUM> are provided in this order from the upstream to the downstream in the yarn running direction. The yarn guide <NUM> is provided, for example, on an extension of the central axis of the yarn supplying bobbin Bs, and guides the yarn Y unwound from the yarn supply package Ps to the downstream side in the yarn running direction. The guide roller <NUM> guides the yarn Y having been guided by the yarn guide <NUM> further to the downstream side in the yarn running direction. The guide roller <NUM> is provided on the front surface of the base <NUM> and above the yarn guide <NUM>. The guide roller <NUM> is rotationally driven by a roller driving motor <NUM>, for example. The roller driving motor <NUM> is, for example, a typical AC motor in which the rotation number is variable. The roller driving motor <NUM> is therefore able to change the rotation speed of the guide roller <NUM>. The roller driving motor <NUM> is electrically connected to the controller <NUM> (see <FIG>). In the present embodiment, the yarn Y is tensioned by a speed difference between the circumferential speed of the guide roller <NUM> and the circumferential speed of the wound package Pw.

The tension sensor <NUM> is provided between the wound package Pw and the guide roller <NUM> in the yarn running direction and is configured to detect the tension of the yarn Y. The tension sensor <NUM> is electrically connected to the controller <NUM> (see <FIG>) and sends a result of detection of the tension to the controller <NUM>.

The controller <NUM> includes members such as CPU, a ROM, and a RAM (storage unit <NUM>). The storage unit <NUM> stores, for example, parameters such as an amount of the wound yarn Y, a winding speed, and the magnitude of tension applied to the yarn Y. The controller <NUM> controls components by using the CPU and a program stored in the ROM, based on the parameters stored in the RAM (storage unit <NUM>), etc..

In the re-winder <NUM> arranged as described above, the yarn Y unwound from the yarn supply package Ps runs toward the downstream side in the yarn running direction. The running yarn Y is wound onto the rotating winding bobbin Bw while being traversed in the left-right direction (traverse direction) by the traverse guide <NUM> (winding operation of winding the yarn).

Basic control of movement of the traverse guide <NUM> by the controller <NUM> will be described with reference to <FIG> is a graph showing the relationship between position of the traverse guide <NUM> and time in the traverse direction. <FIG> is a graph showing the relationship between speed of the traverse guide <NUM> and time in the traverse direction.

The storage unit <NUM> (see <FIG>) of the controller <NUM> stores information regarding the traverse width. The controller <NUM> controls the traverse motor <NUM> based on the information stored in the storage unit <NUM>. With this arrangement, the endless belt <NUM> is reciprocally driven and the traverse guide <NUM> reciprocates in the traverse direction.

In the graph shown in <FIG>, the horizontal axis indicates time whereas the vertical axis indicates position of the traverse guide <NUM> in the traverse direction. For convenience, in the left-right direction, a direction leftward of the center of the region (traverse region) where the traverse guide <NUM> reciprocates will be regarded as a positive direction of the vertical axis of the graph. A direction rightward of the center of the traverse region will be regarded as a negative direction of the vertical axis of the graph.

For example, provided that the traverse width is W, the traverse guide <NUM> reciprocates within a region between -W/<NUM> and W/<NUM> in the traverse direction as shown in <FIG>. To be more specific, for example, at a predetermined time point (the left end of the graph of <FIG>), the traverse guide <NUM> is at the right end (i.e., the position -W/<NUM>). After a predetermined time (T) elapses, the traverse guide <NUM> moves to the left end (the position W/<NUM>). Thereafter, the traverse guide <NUM> is reversed rightward and reaches the right end again. As this operation is repeated, the traverse guide <NUM> reciprocates.

In the graph shown in <FIG>, the horizontal axis indicates time whereas the vertical axis indicates speed of the traverse guide <NUM> in the traverse direction. The following will describe a specific example. When the traverse guide <NUM> is at the right end (the position -W/<NUM>), the speed of the traverse guide <NUM> is zero. The controller <NUM> controls the traverse motor <NUM> to accelerate the traverse guide <NUM> to a predetermined speed (V). Thereafter, the controller <NUM> maintains the speed of the traverse guide <NUM> to be constant until the traverse guide <NUM> reaches a position close to the left end (the position W/<NUM>). When the traverse guide <NUM> reaches the position close to the left end, the controller <NUM> controls the traverse motor <NUM> to perform reversal control as described below. That is to say, the controller <NUM> decelerates the traverse guide <NUM> running leftward (outward in the traverse direction), and reverses the running direction of the traverse guide <NUM> to rightward (inward in the traverse direction) at the position W/<NUM>. Thereafter, the controller <NUM> accelerates the traverse guide <NUM> to a predetermined speed again (as indicated by -V in <FIG>). In the present embodiment, the time between the start of the deceleration of the traverse guide <NUM> and the completion of the re-acceleration in the reversal control is referred to as a reversal time (Tr in <FIG>).

The following will describe the precision winding and the creeping with reference to <FIG> illustrate the precision winding, in each of which a wound package Pw is exploded in the rotational direction. For convenience, as shown in <FIG>, a rotational angle of the wound package Pw at the upper end of each figure is regarded as <NUM> degree, whereas a rotational angle at the lower end of each figure is regarded as <NUM> degrees. <FIG> illustrates the creeping.

To begin with, the following will describe the precision winding. The precision winding is a way of winding with which the ratio (winding ratio) of the rotation number of the winding bobbin Bw to the number of times of reciprocal movement of the traverse guide <NUM> per unit time is maintained to be constant. This makes it possible to control the relationship between the rotational angle of the winding bobbin Bw and the position of the traverse guide <NUM> in the traverse direction, irrespective of the diameter of the wound package Pw.

The storage unit <NUM> (see <FIG>) of the controller <NUM> stores, for example, information (a table and a calculation formula) of the relationship between the rotational angle of the winding bobbin Bw and the position of the traverse guide <NUM> in the traverse direction. As a specific example, the storage unit <NUM> stores the rotational angles of the winding bobbin Bw in association with the positions where acceleration and deceleration of the traverse guide <NUM> in the traverse direction start and the reversal position of the traverse guide <NUM> in the traverse direction. The storage unit <NUM> stores a calculation formula by which the speed and/or acceleration of the traverse guide <NUM> is calculated based on information of the rotational angle of the winding bobbin Bw and information of the position of the traverse guide <NUM>. The controller <NUM> controls the winding motor <NUM> and the traverse motor <NUM> based on the information stored in the storage unit <NUM>. In the present embodiment, the controller <NUM> controls the winding motor <NUM> so that the rotation number of the winding bobbin Bw is maintained to be constant. As a first example, as shown in <FIG>, when the winding ratio is <NUM>, the winding bobbin Bw rotates five times while the traverse guide <NUM> reciprocates once. In other words, as shown in <FIG>, the yarn Y is wound for an amount corresponding to five rotations of the wound package Pw, while the traverse guide <NUM> reciprocates once.

As described above, when the winding ratio is an integer, it is disadvantageous in that the yarn Y is repeatedly wound onto the same path on the surface of the wound package Pw (i.e., a ribbon is formed). In order to avoid this problem, in reality, the winding ratio is set at a value slightly different from an integer (e.g., <NUM>+α) as shown in <FIG>. With this arrangement, in the precision winding, the formation of a ribbon is avoided and the yarn Y is regularly wound in a parallel manner, as the path of the yarn wound on the surface of the wound package Pw is gradually shifted. As a result, the yarn Y is easily unwound from the wound package Pw in a posterior process, and the density of the package is easily controlled in accordance with the use of the wound package Pw.

Now, the creeping will be described. The creeping is an action to temporarily change the traverse width during the winding operation of winding the yarn Y, for the purpose of suppressing the formation of a saddle bag on the wound package Pw. The saddle bag is a problem that an amount of a yarn wound at an end portion of the surface of the wound package Pw in the axial direction is larger than an amount of the yarn wound on other parts of the surface, because, for example, it is typically difficult to swiftly reverse the traverse guide <NUM>. As a result, a level difference tends to be formed on the surface of the wound package Pw, with the result that yarn stitching of the yarn Y may occur. Furthermore, the formation of a saddle bag may deteriorate the shape of the wound package Pw and/or may cause the density of the wound package Pw to be irregular.

As described above, the traverse unit <NUM> is arranged to drive, by the traverse motor <NUM>, the endless belt <NUM> to which the traverse guide <NUM> is attached, in a reciprocal manner. On this account, as the controller <NUM> controls the traverse motor <NUM>, it is possible to change the reversal position of the traverse guide <NUM> at will. For example, as shown in <FIG>, the controller <NUM> is able to switch the traverse width between a predetermined first width (Wa) and a second width (Wb) that is narrower than the first width (i.e., able to perform the creeping). Hereinafter, a state in which the traverse width is equal to the first width will be referred to as a normal state whereas a state in which the traverse width is equal to the second width will be referred to as a creeping state. The distance between the reversal position of the traverse guide <NUM> in the normal state and the reversal position of the traverse guide <NUM> in the creeping state is ΔW (=(Wa-Wb)/<NUM>). Hereinafter, this distance will be referred to as a creeping amount. The controller <NUM> is able to change the creeping amount by controlling the traverse motor <NUM>. The creeping amount is typically about <NUM> to <NUM> but is not limited to this range. The controller <NUM> is able to perform the creeping at a desired timing. For example, as shown in <FIG>, the controller <NUM> performs the creeping once while the traverse guide <NUM> reciprocates three times. As compared to cases where the creeping is not performed, the creeping makes it possible to reduce the amount of the yarn wound at the end portion in the axial direction of the wound package Pw, and therefore to suppress the formation of saddle bag.

If the creeping is performed while the precision winding is performed, the following problem may occur. The following will specifically describe the problem with reference to <FIG> and <FIG>. <FIG> is a graph similar to that of <FIG> and shows the relationship between speed of the traverse guide <NUM> and time when the traverse width is simply narrowed (as described below) during the creeping. <FIG> is an enlarged view of the left end portion of the wound package Pw and shows the paths of the yarn Y on the surface of the wound package Pw when the traverse width is simply narrowed during the creeping. <FIG> is a graph similar to that of <FIG> and shows the relationship between speed of the traverse guide <NUM> and time when the traversal speed is simply decreased (as described below) during the creeping. <FIG> is an enlarged view of the left end portion of the wound package Pw and shows the paths of the yarn Y on the surface of the wound package Pw when the traversal speed is simply decreased during the creeping. In the graphs shown in <FIG> and <FIG>, solid lines indicate the traversal speed in the normal state whereas dotted lines indicate the traversal speed in the creeping state.

To begin with, a case where the traverse width is simply narrowed in the creeping state as compared to the normal state will be described. When the traverse width is simply narrowed, as shown in <FIG>, only a timing to perform the reversal control is changed without changing the above-described reversal time (Tr) and the traversal speed (V) when the reversal control is not performed. In this case, in the creeping state, the traverse width is narrowed by simply reversing the traverse guide <NUM> at a timing earlier than the reversal in the normal state. As a result, the traverse cycle is shortened in the creeping state as compared to the normal state. On this account, the precision winding is not properly done, and hence the yarn Y runs on the surface of the wound package Pw along the paths shown in <FIG>. In other words, yarn parts Y1 and Y2 which are parts of the yarn Y wound onto the wound package Pw in the normal state are reversed at points <NUM> and <NUM> on an end face Pw1 of the wound package Pw, respectively. Furthermore, a yarn part Y3 which is a part of the yarn Y wound onto the wound package Pw in the creeping state is reversed at a point <NUM> which is positioned inward of the points <NUM> and <NUM> by ΔW in the traverse direction. Assume that a reversal position when the traverse width of the yarn Y3 being wound is identical with the traverse width in the normal state is a point <NUM>. The point <NUM> is positionally different from the point <NUM> in the rotational direction such that the point <NUM> is formed in the wound package Pw at a smaller rotational angle (i.e., at an earlier timing) than the point <NUM>. To put it differently, the yarn part Y3 is wound at a location significantly deviated from a path <NUM> where the yarn Y is wound when the creeping is not performed. As a result, the shape of the surface of the wound package Pw is poor.

Now, a case where the traversal speed is simply decreased in the creeping state as compared to the normal state will be described. When the traversal speed is simply decreased, as shown in <FIG>, the traversal speed when the reversal control is not performed is decreased as compared to the normal state, without changing the reversal time (Tr) and the timing to perform the reversal control. For example, if the traversal speed in the normal state is Va and the traversal speed in the creeping state is Vb, Vb is smaller than Va. In this case, the winding ratio is maintained to be constant because the traverse cycle is identical between the normal state and the creeping state. In the case above, furthermore, the yarn part Y3 which is wound in the creeping is reversed at a point <NUM> as shown in <FIG>. The point <NUM> is at the same position as the above-described point <NUM> in the rotational direction. However, in this case, the angle (helix angle) between the yarn Y and the wound package Pw becomes disadvantageously different between the normal state and the creeping state, on account of the change of the traversal speed. To put it differently, the yarn parts Y1 and Y2 which are parts of the yarn Y wound onto the wound package Pw in the normal state are not parallel to the yarn part Y3 which is a part of the yarn Y wound onto the wound package Pw in the creeping state. As a result, the shape of the surface of the wound package Pw is poor. Under this circumstance, in order to suppress the winding ratio from being changed and to suppress the shape of the surface of wound package Pw from being poor even when the creeping is performed during the precision winding, the controller <NUM> performs control as described below in the present embodiment.

The yarn winding method performed by the controller <NUM> by using the above-described reversal control will be detailed with reference to <FIG>, <FIG>, and <FIG>. <FIG> is a graph showing the relationship between position of the traverse guide <NUM> and time in the traverse direction. <FIG> is a graph showing the relationship between speed of the traverse guide <NUM> and time in the traverse direction. <FIG> is a graph showing the relationship between acceleration of the traverse guide <NUM> and time in the traverse direction. <FIG> is a graph showing the relationship between the later-described width of a reversal region and a creeping amount. <FIG> are similar to <FIG> and <FIG> and show the paths of the yarn Y on the surface of the wound package Pw. The descriptions below assume that the rotation number of the wound package Pw is constant.

To begin with, as the reversal control in the normal state (first reversal control), the controller <NUM> performs the following control. In the first reversal control, the controller <NUM> reverses the traverse guide <NUM> at the first reversal position (Wa/<NUM> in <FIG>) in the traverse direction (first reversal step). In the first reversal control, the time between the start of the deceleration of the traverse guide <NUM> and the completion of the re-acceleration is referred to as a first reversal time (Tra). In addition to the above, as the reversal control (second reversal control) in the creeping state, the controller <NUM> performs the following control. In the second reversal control, the controller <NUM> reverses the traverse guide <NUM> at the second reversal position (Wb/<NUM> in <FIG>) in the traverse direction (second reversal step). In the second reversal control, the time between the start of the deceleration of the traverse guide <NUM> to the completion of the re-acceleration is referred to as a second reversal time (Trb). A region in which the traverse guide <NUM> moves in the traverse direction in a period between the start of deceleration and the completion of re-acceleration is referred to as a reversal region. The width of the reversal region in the second reversal control is referred to as Wt, for example (see <FIG>).

As shown in <FIG>, the controller <NUM> arranges the second reversal time to be longer than the first reversal time (Trb>Tra). To put it differently, in the second reversal control, the controller <NUM> gently accelerates and decelerates the traverse guide <NUM> as compared to the first reversal control. To be more specific, as compared to the maximum value (Aa) of the acceleration during the first reversal time in the first reversal control, the maximum value (Ab) of the acceleration during the second reversal time in the second reversal control is arranged to be small (see <FIG>). In other words, as compared to a time average of the acceleration during the first reversal time in the first reversal control, a time average of the acceleration during the second reversal time in the second reversal control is arranged to be small.

As a result, the traverse cycle is arranged to be identical between the normal state and the creeping state even when the traverse width is different between the normal state and the creeping state (see <FIG>). A variation in the winding ratio is therefore suppressed. In addition to the above, the controller <NUM> arranges the traversal speed when the reversal control is not performed to be identical between the normal state and the creeping state (see <FIG>). Furthermore, in the second reversal control, the controller <NUM> controls the traverse motor <NUM> so that the traverse guide <NUM> is at the second reversal position when a time (Trb/<NUM>) that is a half of the second reversal time elapses from the start of the deceleration of the traverse guide <NUM>.

As a result of the control described above, the yarn Y is wound onto the wound package Pw as shown in <FIG>. In other words, a part (yarn part Y3) of the yarn Y wound onto the wound package Pw in the creeping state is reversed at a point <NUM> in the traverse direction. The point <NUM> is at the same position as the above-described point <NUM> in the rotational direction. In the second reversal control (i.e., when the traverse guide <NUM> moves in the above-described reversal region), the yarn part Y3 is wound onto the wound package Pw so as to form an arc on the surface (see a hatched region <NUM> in <FIG>). Because the traversal speed when the reversal control is not performed is identical between the normal state and the creeping state, the helix angle when the reversal control is not performed is identical between the normal state and the creeping state. Therefore, on the inner side of the region <NUM> in the traverse direction, the yarn part Y3 is wound along the above-described path <NUM>. For this reason, in the present embodiment, the precision winding is properly done and it is possible to suppress the shape of the surface of the wound package Pw from being poor.

As described above, the traverse guide <NUM> is at the second reversal position when a time (Trb/<NUM>) that is a half of the second reversal time elapses from the start of the deceleration of the traverse guide <NUM>. On this account, the reversed portion of the yarn part Y3 is symmetrical about the central axis of the wound package Pw in shape. In other words, the reversed portion of the yarn part Y3 is neatly formed.

The controller <NUM> arranges the width of the reversal region in the traverse direction to be long when the creeping amount is large (see <FIG>). For example, when the creeping amount is ΔW1 which is larger than ΔW, the controller <NUM> arranges the width of the reversal region to be Wt1 which is wider than Wt (see <FIG>). In other words, when the second reversal time becomes long as the traverse width in the creeping state is narrowed, the region in which the traverse guide <NUM> is movable in the traverse direction in the second reversal control becomes wide. It is therefore possible to avoid a problem that the traverse guide <NUM> is left in a narrow region in the traverse direction for a long time. Furthermore, with the arrangement above, the arc formed by the yarn part Y3 when it is wound onto the wound package Pw is large (see a region <NUM> in <FIG>).

As described above, the second reversal time is longer than the first reversal time. As the reversal time in the creeping state is actively elongated, the movement cycle of the traverse guide <NUM> is arranged to be long in the creeping state. This makes it possible to arrange the movement cycle of the traverse guide <NUM> to be identical between the normal state and the creeping state. It is therefore possible to prevent the winding ratio from being varied.

In addition to the above, because the traverse cycle in the creeping state is adjustable by adjusting the second reversal time as described above, the running speed of the traverse guide <NUM> is arranged to be identical between the normal state and the creeping state when the reversal is not performed. It is therefore possible to arrange the angles of the yarn Y wound onto the surface of the wound package Pw to be identical. It is therefore possible to suppress the shape of the surface of the wound package Pw from being poor.

In addition to the above, the width of the reversal region in the traverse direction is arranged to be long when the creeping amount is large. In other words, when the second reversal time becomes long as the traverse width in the creeping state is narrowed, the region in which the traverse guide <NUM> is movable in the second reversal control becomes wide. On this account, it is possible to avoid a problem that the traverse guide <NUM> is left in a narrow region in the traverse direction for a long time. It is therefore possible to suppress the yarn Y from being wound onto a narrow region on the surface of the wound package Pw in a concentrated manner.

In addition to the above, the time from the start of the deceleration of the traverse guide <NUM> to the arrival of the traverse guide <NUM> at the second reversal position is arranged to be equal to the time from the departure of the traverse guide <NUM> from the second reversal position to the completion of the re-acceleration. On this account, the reversed portion of the yarn Y is shaped to be symmetrical about the central axis of the wound package Pw. (In other words, the reversed portion is neatly formed in shape. ) It is therefore possible to suppress the shape of the reversed portion of the surface of the wound package Pw from being poor.

In addition to the above, the controller <NUM> performs control based on information of the relationship between the rotational angle of the winding bobbin Bw and the position of the traverse guide <NUM>. This makes it possible to simplify the complicated operation of performing the creeping while maintaining the winding ratio to be constant, as compared to, for example, control utilizing a complicated mechanical structure. Furthermore, it is possible to easily adjust the position, speed, etc. of the traverse guide <NUM> in the second reversal control by rewriting the information.

The traverse motor <NUM> is configured to be able to rotate forward and backward. It is therefore possible to cause the traverse guide <NUM> to reciprocate by driving the traverse motor <NUM> forward and backward. For this reason, the position and timing of the reversal of the traverse guide <NUM>, etc. can be finely controlled by the controller. Fine control of the creeping can therefore be easily done.

In addition to the above, as the part of the endless belt <NUM> to which the traverse guide <NUM> is attached is tensioned to be linear and is reciprocated, the traverse guide <NUM> is easily reciprocated linearly. Regular winding of the yarn Y onto the surface of the wound package Pw is therefore facilitated.

Claim 1:
A yarn winding device (<NUM>) which is configured to form a package (Pw) by winding a running yarn (Y) onto a rotating bobbin (Bw) while the yarn (Y) is traversed by a traverse guide (<NUM>) and performing precision winding in which a winding ratio which is a ratio of the rotation number of the bobbin (Bw) to the number of times of reciprocal movement of the traverse guide (<NUM>) per unit time to be constant, the yarn winding device (<NUM>) comprising:
a guide driving unit (<NUM>) which is configured to reciprocate the traverse guide (<NUM>) in a predetermined traverse direction and is able to change a reversal position of the traverse guide (<NUM>) during a winding operation of winding the yarn (Y); and a control unit (<NUM>),
the control unit (<NUM>) being configured to perform:
first reversal control in which the guide driving unit (<NUM>) is controlled so that the traverse guide (<NUM>) running outward in the traverse direction at a predetermined speed is decelerated, the running direction of the traverse guide (<NUM>) is reversed to inward at a predetermined first reversal position, and then the traverse guide (<NUM>) is re-accelerated to the predetermined speed; and
second reversal control in which the guide driving unit (<NUM>) is controlled so that the traverse guide (<NUM>) running outward in the traverse direction at the predetermined speed is decelerated, the running direction of the traverse guide (<NUM>) is reversed to inward at a second reversal position which is on the inner side of the first reversal position, and then the traverse guide (<NUM>) is re-accelerated to the predetermined speed,
during the precision winding, as compared to a first reversal time which is between start of deceleration to completion of re-acceleration in the first reversal control, a second reversal time which is between start of deceleration of the traverse guide (<NUM>) and completion of re-acceleration in the second reversal control being arranged to be long;
characterized in that
the control unit (<NUM>) is configured to arrange the maximum value of the acceleration in the second reversal time to be identical with the maximum value of the acceleration in the first reversal time and to stop the traverse guide (<NUM>) at the second reversal position in the traverse direction for a predetermined time and then accelerate the traverse guide (<NUM>) again.