JP7804499B2 - Fiber-spreading device and fiber-spreading method - Google Patents

Description

The present invention relates to a fiber-spreading device and fiber-spreading method, and in particular to a fiber-spreading device and fiber-spreading method for spreading carbon fiber bundles.

Numerous methods for spreading carbon fibers have been proposed. For example, Patent Document 1 discloses a method for spreading carbon fibers using a vibrating bar.

Patent Document 2 also describes a fiber-spreading device that includes a fiber-spreading promoting member with corners extending in a direction perpendicular to the conveyance direction of the fiber bundle, and conveys the fiber bundle while pressing it against the corners of the fiber-spreading promoting member, thereby causing a widthwise shift in the fibers that make up the fiber bundle and spreading the fiber bundle. Patent Document 2 also describes further spreading the fiber bundle by blowing air onto the fiber bundle from an air supplier.

Patent Document 3 also describes a fiber-spreading device that softens the oil and sizing agent (sizing agent) by bringing a carbon fiber bundle into contact with the surface of a heated fiber bundle contacting means and passing the carbon fiber bundle through the fiber bundle contacting means while bending the carbon fiber bundle.

Japanese Patent Application Laid-Open No. 2005-163196 JP 2014-129633 A Japanese Patent Application Laid-Open No. 2017-203235

However, when carbon fiber bundles are spread using a vibrating bar, fluff can occur on the fiber bundle. This fluff can cause the fiber bundle to wrap around the rolls in the subsequent spread process, lowering the yield rate and potentially resulting in differences in the amount of fiber supplied per bundle. Furthermore, when air is used to spread the fibers to a wider spread width, the air scatters the fibers, which can lead to the need for dust collectors and enclosures, which can be costly. This makes it extremely difficult to stably spread carbon fiber bundles to a wide width.

The present invention was made in consideration of the above, and aims to provide a fiber spreading device and fiber spreading method that can stably produce wide-spread fiber bundles.

In order to solve the above-mentioned problems and achieve the objectives, the fiber spreading device of the present invention comprises a payout machine that continuously pays out a long fiber bundle in which carbon fibers are bundled with a sizing agent; a pair of feed rolls that are each formed in a cylindrical shape and rotate in opposite directions while sandwiching the fiber bundle paid out from the payout machine between them, thereby transporting the fiber bundle downstream in a transport path for the fiber bundle; and a plurality of rod-shaped feed rolls that are arranged between the payout machine and the feed rolls in the transport path and are positioned so that they alternately come into contact with different surfaces of the fiber bundle as they move from the upstream side to the downstream side in the transport path. and a pair of speed-increasing relaxation rolls each formed cylindrically and arranged between the spreading bars and the feed roll in the transport path, rotating at a peripheral speed that is no more than 650% of the peripheral speed of the feed roll, with the outer circumferential surfaces of the rolls contacting the fiber bundle. The pair of speed-increasing relaxation rolls includes a first speed-increasing relaxation roll arranged downstream of the spreading bars in the transport path, and a second speed-increasing relaxation roll arranged between the first speed-increasing relaxation roll and the feed roll in the transport path, which contacts a surface of the fiber bundle different from the surface of the fiber bundle that contacts the first speed-increasing relaxation roll.

In order to solve the above-mentioned problems and achieve the objectives, the fiber-spreading method of the present invention continuously pays out a long fiber bundle obtained by bundling carbon fibers with a sizing agent from a payout machine, sandwiches the fiber bundle paid out from the payout machine between a pair of feed rolls rotating in opposite directions and transports it downstream in a transport path of the fiber bundle, and spreads the fiber bundle by alternately contacting different surfaces of the fiber bundle with the plurality of rod-shaped fiber-spreading bars arranged between the payout machine and the feed rolls in the transport path as the fiber bundle moves from the upstream side to the downstream side in the transport path. A fiber-spreading method in which the fiber bundle is brought into contact with the outer peripheral surfaces of a pair of accelerating speed relaxation rolls, each of which is arranged between the spreading bar and the feed roll in the transport path, and which are cylindrical and rotate at a peripheral speed that is 650% or less of the peripheral speed of the feed roll, the pair comprising a first accelerating speed relaxation roll arranged downstream of the spreading bar in the transport path, and a second accelerating speed relaxation roll arranged between the first accelerating speed relaxation roll and the feed roll in the transport path, and the fiber bundle is spread by bringing different surfaces of the fiber bundle into contact with the first accelerating speed relaxation roll and the second accelerating speed relaxation roll.

The fiber-spreading device and fiber-spreading method of the present invention have the effect of stably producing wide-spread fiber bundles.

FIG. 1 is a schematic diagram of a fiber-spreading device according to an embodiment. FIG. 2 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which the first speed-increasing/relaxing roll is disposed below the second speed-increasing/relaxing roll. FIG. 3 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which a pair of feed rolls are arranged side by side in the second direction Y. In FIG. FIG. 4 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which a pair of feed rolls are arranged side by side in the second direction Y. In FIG. FIG. 5 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which a pair of speed-up relaxation rolls are arranged side by side in the second direction Y. FIG. 6 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which a pair of speed-up relaxation rolls are arranged side by side in the second direction Y. FIG. 7 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which a pair of speed-up/relaxation rolls and a pair of feed rolls are arranged side by side in the second direction Y. FIG. 8 is a schematic diagram showing a modified example of the fiber-spreading device according to the embodiment, in which a pair of speed-up/relaxation rolls and a pair of feed rolls are arranged side by side in the second direction Y. FIG. 9 is a schematic diagram showing the device configuration of the fiber spreading device used in the evaluation test. FIG. 10 is a table showing the results of the evaluation test.

Embodiments of a fiber-spreading device and fiber-spreading method according to the present disclosure are described in detail below with reference to the drawings. Note that the present invention is not limited to these embodiments. Furthermore, the components in the following embodiments include those that are interchangeable and easily conceivable by those skilled in the art, or those that are substantially identical.

[Embodiment]
FIG. 1 is a schematic diagram of a fiber-spreading device 10 according to an embodiment. The following description will use a first direction X, a second direction Y, and a third direction Z, which are perpendicular to one another. The first direction X is the direction in which the central rotation axes of a reel-out machine 20, an acceleration/relaxation roll 40, a guide roll 50, and a feed roll 60, which will be described later, extend. The first direction X is the direction extending horizontally when the fiber-spreading device 10 is installed in an arbitrary installation location and used in a normal usage mode. The second direction Y is a direction perpendicular to the first direction X and is a direction perpendicular to the first direction X in the horizontal direction when the fiber-spreading device 10 is installed in an arbitrary installation location and used in a normal usage mode. The third direction Z is a direction perpendicular to both the first direction X and the second direction Y. Therefore, the third direction Z is the vertical direction or the direction of gravity when the fiber-spreading device 10 is installed in an arbitrary installation location and used in a normal usage mode. In the following description, the upper side in the direction of gravity when the fiber-spreading device 10 is used in a normal manner will be referred to as the upper side of the fiber-spreading device 10, and the lower side in the direction of gravity will be referred to as the lower side of the fiber-spreading device 10.

<Opening device 10>
The fiber-spreading device 10 according to this embodiment is a device that can spread a long fiber bundle 105 in which carbon fibers are bundled with a sizing agent. That is, the fiber bundle 105 is a bundle of carbon fibers in which carbon fibers are bundled with a sizing agent made of a resin material or the like, and the fiber-spreading device 10 is a device that spreads the fiber bundle 105 thus configured into a thin, wide shape.

The fiber-spreading device 10 comprises a payout machine 20, a fiber-spreading bar 30, an accelerating/relaxing roll 40, a guide roll 50, and a feed roll 60. The payout machine 20, the fiber-spreading bar 30, the accelerating/relaxing roll 40, the guide roll 50, and the feed roll 60 are all positioned at the same position in the first direction X, and are respectively arranged on a transport path 110 for the fiber bundle 105 to be spread by the fiber-spreading device 10. In other words, the transport path 110 for the fiber bundle 105 is formed as a continuous path for transporting the fiber bundle 105 by looping the long fiber bundle 105 around or bringing it into contact with the payout machine 20, the fiber-spreading bar 30, the accelerating/relaxing roll 40, the guide roll 50, and the feed roll 60.

In addition, in this embodiment, the fiber bundle 105 unwound from the unwinder 20 is transported along the transport path 110 of the fiber bundle 105 from the side where the unwinder 20 is located to the side where the feed roll 60 is located. Therefore, in the fiber spreading device 10 according to this embodiment, the side of the transport path 110 of the fiber bundle 105 where the unwinder 20 is located is the upstream side, and the side where the feed roll 60 is located is the downstream side, and the fiber bundle 105 is transported.

<Feeding machine 20>
The unwinder 20 is formed in a cylindrical shape, and the roving 100, on which the fiber bundle 105 is wound in a cylindrical shape, is attached to the outer circumferential surface of the cylinder. The unwinder 20 is rotatable around the axis of the cylinder as a central rotation axis, and is disposed such that the direction in which the central rotation axis extends is the first direction X. By rotating around the central rotation axis, the unwinder 20 can continuously unwind the fiber bundle 105 from the roving 100 attached to the unwinder 20.

In addition, multiple rovings 100 can be attached to the unwinding machine 20, arranged in the first direction X. While Figure 1 is a schematic diagram of a single roving 100 attached to the unwinding machine 20 in the first direction X, multiple fiber bundles 105 are arranged in the first direction X in the fiber spreading device 10, and multiple conveying paths 110 such as those shown in Figure 1 are formed in the first direction X.

<Feed roll 60>
A pair of feed rolls 60 are provided, and are arranged at positions in at least one of the second direction Y and the third direction Z that are different from the unwinding machine 20. In this embodiment, as shown in FIG. 1 , the feed rolls 60 are arranged at the same positions as the unwinding machine 20 in the third direction Z, and at a different position from the unwinding machine 20 in the second direction Y.

The pair of feed rolls 60 are each formed in a cylindrical shape and are arranged so that the direction in which their rotational axes 67 extend corresponds to the first direction X, and each is rotatable about the rotational axis 67. The cylindrical feed rolls 60 preferably have a diameter of approximately 50 mm to 300 mm. The pair of feed rolls 60 rotate in opposite directions while sandwiching the fiber bundle 105 unwound from the unwinder 20 between them, thereby transporting the fiber bundle 105 downstream of the fiber spreading device 10 along the transport path 110 for the fiber bundle 105.

More specifically, the pair of feed rolls 60 includes a first feed roll 61 and a second feed roll 62. The first feed roll 61 has an outer circumferential surface 64 made of a resilient rubber material, while the second feed roll 62 has an outer circumferential surface 64 with a matte finish. An air cylinder 66 is connected to the first feed roll 61, and the first feed roll 61 is pressed against the second feed roll 62 by the force applied by the air cylinder 66. A drive motor 65 is connected to the second feed roll 62, and the second feed roll 62 can rotate around a rotation center axis 67 by the driving force transmitted from the drive motor 65.

The hardness of the rubber material forming the outer peripheral surface 64 of the first feed roll 61 is preferably set appropriately depending on the magnitude of the force pressing the first feed roll 61 against the second feed roll 62, the conveying speed of the fiber bundle 105, etc. The drive device connected to the first feed roll 61 and pressing the first feed roll 61 against the second feed roll 62 may be something other than the air cylinder 66. For example, a hydraulic cylinder may be connected to the first feed roll 61, and the first feed roll 61 may be configured to be pressed against the second feed roll 62 by the force applied by the hydraulic cylinder.

The outer peripheral surface 64 of the first feed roll 61 is pressed against the outer peripheral surface 64 of the second feed roll 62 by the force of the air cylinder 66. As a result, when the second feed roll 62 rotates due to the driving force transmitted from the drive motor 65, the first feed roll 61 also rotates. In other words, the first feed roll 61 rotates as the portion of the outer peripheral surface 64 of the first feed roll 61 that contacts the second feed roll 62 moves in the same direction as the portion of the outer peripheral surface 64 of the second feed roll 62 that contacts the first feed roll 61. As a result, the first feed roll 61 rotates in the opposite direction to the second feed roll 62 when viewed along the rotation center axis 67.

The rotation direction of the first feed roll 61 and the second feed roll 62 is such that the opposing portions of the outer surface 64 of the first feed roll 61 and the outer surface 64 of the second feed roll 62 move from the upstream side of the conveying path 110 of the fiber bundle 105 toward the downstream side of the fiber spreading device 10.

The pair of feed rolls 60 rotate due to the driving force transmitted from the drive motor 65, and by rotating while sandwiching the fiber bundle 105 unwound from the unwinder 20 between the first feed roll 61 and the second feed roll 62, the fiber bundle 105 can be transported downstream along the fiber bundle 105 transport path 110. In other words, because the outer peripheral surface 64 of the first feed roll 61 is made of a resilient rubber material, the outer peripheral surface 64 of the first feed roll 61 elastically deforms in the area where the fiber bundle 105 is positioned between the first feed roll 61 and the second feed roll 62, allowing the fiber bundle 105 to be sandwiched between the first feed roll 61 and the second feed roll 62. As a result, the first feed roll 61 and second feed roll 62 come into contact with the fiber bundle 105 at high pressure, and as the first feed roll 61 and second feed roll 62 rotate, the fiber bundle 105 moves and is transported due to the frictional force between the first feed roll 61 and the second feed roll 62.

Because the fiber bundle 105 is transported by a pair of feed rolls 60 in this manner, the transport speed of the fiber bundle 105 can be adjusted by adjusting the rotational speed of the feed rolls 60, which are rotated by the driving force transmitted from the drive motor 65.

The unwinder 20 unwinds the fiber bundle 105 by rotating due to the tension applied to the fiber bundle 105 from a pair of feed rolls 60. The unwinder 20 is configured as a so-called back tension roll that generates tension in the opposite direction to the traveling direction of the fiber bundle 105 unwound from the unwinder 20. This allows the unwinder 20 to apply a force to the fiber bundle 105 unwound from the unwinder 20 in the opposite direction to the direction in which the fiber bundle 105 advances along the conveying path 110 due to the tension applied by the feed rolls 60. In other words, the unwinder 20 is able to apply a force to the fiber bundle 105 in the opposite direction to the direction in which the fiber bundle 105 is unwound from the unwinder 20.

<Opening bar 30>
The plurality of fiber spreading bars 30 are formed in a rod shape and are arranged non-rotatably between the unwinder 20 and the feed rolls 60 on the conveying path 110. In this embodiment, the plurality of fiber spreading bars 30 are arranged between the unwinder 20 and the feed rolls 60 in the second direction Y. The plurality of fiber spreading bars 30 formed in a rod shape are arranged such that their extension directions are in the first direction X. The plurality of fiber spreading bars 30 are arranged in a so-called staggered pattern between the unwinder 20 and the feed rolls 60, from the side where the unwinder 20 is located toward the side where the feed rolls 60 are located, at positions between the unwinder 20 and the feed rolls 60. That is, the plurality of fiber spreading bars 30 are arranged in a staggered pattern from the upstream side toward the downstream side on the conveying path 110 of the fiber bundle 105.

More specifically, the multiple fiber-spreading bars 30 are arranged such that their positions in the third direction Z alternate between one direction and the other as they move from the side where the unwinder 20 is located toward the side where the feed roll 60 is located. In other words, of the multiple fiber-spreading bars 30, the fiber-spreading bar 30 closest to the unwinder 20 is adjacent to the fiber-spreading bar 30 on the side where the feed roll 60 is located, and the adjacent fiber-spreading bar 30 on the side where the feed roll 60 is located is offset in one direction in the third direction Z from the fiber-spreading bar 30 offset in one direction in the third direction Z.

As a result, the multiple fiber-spreading bars 30 are arranged in a staggered pattern, with their positions in the third direction Z being alternately shifted from the upstream side to the downstream side on the conveying path 110 of the fiber bundle 105. In this embodiment, three fiber-spreading bars 30 are arranged, and the three fiber-spreading bars 30 are aligned in the second direction Y between the unwinder 20 and the feed roll 60, with the two fiber-spreading bars 30 at both ends positioned close to each other in the third direction Z, and the central fiber-spreading bar 30 positioned at a different position in the third direction Z from the two fiber-spreading bars 30 at both ends. In other words, in this embodiment, of the three fiber-spreading bars 30 aligned in the second direction Y, the central fiber-spreading bar 30 is positioned higher in the third direction Z than the two fiber-spreading bars 30 at both ends.

The fiber bundles 105 are threaded around each of the multiple spreading bars 30 arranged in a staggered pattern as shown above. The fiber bundles 105 are threaded around the spreading bars 30 from the outside in a direction in which the positions of the spreading bars 30 alternately shift as they move from upstream to downstream along the fiber bundle 105 transport path 110. In other words, when multiple spreading bars 30 are arranged in a staggered pattern by being aligned in the second direction Y and alternately shifting their positions in the third direction Z, the fiber bundles 105 are threaded around the spreading bars 30 from below for those spreading bars 30 that are relatively lower in the third direction Z, and the fiber bundles 105 are threaded around the spreading bars 30 from above for those spreading bars 30 that are relatively higher in the third direction Z.

As a result, the multiple spreading bars 30 alternately contact different surfaces of the fiber bundle 105 as they move from the upstream side to the downstream side of the conveying path 110 of the fiber bundle 105. In other words, the multiple spreading bars 30 are positioned so that they alternately contact different surfaces of the fiber bundle 105 as they move from the upstream side to the downstream side of the conveying path 110 of the fiber bundle 105.

The opening bars 30 arranged in this manner have a matte surface. The opening bars 30 are also heatable. For example, a gaseous or liquid heating medium heated by a heating device (not shown) can be passed through the interior of the opening bars 30, and the opening bars 30 can be heated by the transfer of heat from the heating medium flowing inside the opening bars 30. This allows the opening bars 30 to heat the fiber bundles 105 that come into contact with the opening bars 30.

<Speed-up relaxation roll 40>
A pair of accelerating relaxation rolls 40 are arranged between the opening bar 30 and the feed roll 60 in the transport path 110 of the fiber bundle 105. Each of the pair of accelerating relaxation rolls 40 is formed in a cylindrical shape, and the outer circumferential surface 44 of each roll has a matte surface. The pair of accelerating relaxation rolls 40 formed in a cylindrical shape are arranged so that the direction in which the rotation central shaft 47 extends is the first direction X, and each roll is rotatable about the rotation central shaft 47. The diameter of the accelerating relaxation roll 40 is larger than the diameter of the feed roll 60. The diameter of the accelerating relaxation roll 40 is desirably about 100 mm to 300 mm, for example.

Each of the pair of speed-up relaxation rolls 40 can be configured to allow a heat medium, such as a gas or liquid heated by a heating device (not shown), to pass through the interior, and can be heated by the heat transfer from the heat medium flowing inside the speed-up relaxation roll 40. This allows the speed-up relaxation roll 40 to heat the fiber bundle 105 that comes into contact with the speed-up relaxation roll 40.

The pair of speed-increasing relaxation rolls 40 includes a first speed-increasing relaxation roll 41 and a second speed-increasing relaxation roll 42. The first speed-increasing relaxation roll 41 is disposed downstream of the opening bar 30 in the transport path 110 of the fiber bundle 105. The second speed-increasing relaxation roll 42 is disposed between the first speed-increasing relaxation roll 41 and the feed roll 60 in the transport path 110 of the fiber bundle 105.

The first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are disposed at a predetermined distance. In this embodiment, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are positioned at approximately the same position in the second direction Y, and the second speed-up relaxation roll 42 is positioned below the first speed-up relaxation roll 41 in the third direction Z. Therefore, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are disposed at a predetermined distance in the third direction Z. It is desirable that the distance between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 be as close as possible, for example, approximately 1 mm to 50 mm. The distance between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 here is, in more detail, the distance between the opposing outer peripheral surfaces 44 of the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42; in other words, the roll gap.

A drive motor 45 is connected to the pair of speed-up relaxation rolls 40, and each of the pair of speed-up relaxation rolls 40 can rotate about a central rotation axis 47 by the driving force transmitted from the drive motor 45. In this embodiment, the drive motor 45 is connected to the second speed-up relaxation roll 42, and the driving force generated by the drive motor 45 is transmitted to the second speed-up relaxation roll 42.

The first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are connected via a power transmission mechanism (not shown) consisting of gears or the like, and the driving force transmitted from the drive motor 45 to the second speed-up relaxation roll 42 is transmitted to the first speed-up relaxation roll 41 via the power transmission mechanism. As a result, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 can each rotate around their respective rotation center axes 47 by the driving force transmitted from the drive motor 45.

In this case, the power transmission mechanism that transmits the driving force between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 is configured to rotate the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 in opposite directions. As a result, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 can rotate in opposite directions around their respective rotation central axes 47 by the driving force transmitted from the drive motor 45.

The fiber bundle 105 is wound around both the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 at a position downstream of the opening bar 30 on the fiber bundle 105 transport path 110, and the outer peripheral surfaces 44 of the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 contact the fiber bundle 105. At this time, the fiber bundle 105 is wound around the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 so that different surfaces of the fiber bundle 105 contact the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42. In other words, when the fiber bundle 105 is wound around the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42, the second speed-up relaxation roll 42 contacts a surface of the fiber bundle 105 that is different from the surface of the fiber bundle 105 that contacts the first speed-up relaxation roll 41.

Specifically, when viewing the speed-up relaxation roll 40 in a direction along the central axis 47 of the speed-up relaxation roll 40, the fiber bundle 105 is wound around the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 in an S-shape or an inverted S-shape. That is, the portion of the fiber bundle 105 from the position where it is wound around the fiber spreading bar 30 toward the first speed-up relaxation roll 41 is wound around the first speed-up relaxation roll 41 from the side opposite the side where the second speed-up relaxation roll 42 is located. The fiber bundle 105 further passes between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 from the position where it is wound around the first speed-up relaxation roll 41, facing the side where the second speed-up relaxation roll 42 is located, and is wound around the second speed-up relaxation roll 42. As a result, the fiber bundle 105 is wound around the first speed-increasing relaxation roll 41 and the second speed-increasing relaxation roll 42 in an S-shape or an inverted S-shape.

When viewed from the portion of the fiber bundle 105 located between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42, the portion of the fiber bundle 105 that is wound around the first speed-up relaxation roll 41 and the portion that is wound around the second speed-up relaxation roll 42 are wound around such that different surfaces come into contact with the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42. As a result, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42, around which the fiber bundle 105 is wound, come into contact with different surfaces of the fiber bundle 105.

Thus, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 contact different surfaces of the fiber bundle 105, but when rotated by the driving force transmitted from the drive motor 45, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 rotate in opposite directions. Therefore, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 rotate in a direction such that the portion of their outer circumferential surface 44 that is in contact with the fiber bundle 105 moves from the upstream side to the downstream side in the conveying direction of the fiber bundle 105.

At that time, the accelerating and relaxing rolls 40 rotate at an increased speed relative to the peripheral speed of the feed roll 60 within a range in which the peripheral speed is 650% or less. In other words, the drive motor 45 that rotates the accelerating and relaxing rolls 40 rotates the first accelerating and relaxing rolls 41 and the second accelerating and relaxing rolls 42 at an increased speed relative to the peripheral speed of the feed roll 60 within a range in which the peripheral speed is 650% or less relative to the peripheral speed of the feed roll 60. Specifically, each of the pair of accelerating and relaxing rolls 40 rotates at an increased speed relative to the feed roll 60 within a range in which the peripheral speed is 200% or more and 650% or less relative to the peripheral speed of the feed roll 60.

The acceleration relaxation roll 40 rotates at a peripheral speed faster than that of the feed roll 60, and once the rotational speed reaches a set speed, it maintains that speed and rotates at a constant speed, thereby relaxing the tension in the fiber bundle 105 and opening the fiber bundle 105. The peripheral speed of the acceleration relaxation roll 40, which rotates at a speed faster than that of the feed roll 60, can be changed separately from the peripheral speed of the feed roll 60. In other words, the rotational speed of the acceleration relaxation roll 40, which rotates using the driving force transmitted from the drive motor 45, can be changed separately from the rotational speed of the feed roll 60.

The accelerating/relaxing rolls 40 and the feed rolls 60 are each rotatable, but the pair of accelerating/relaxing rolls 40 and the pair of feed rolls 60 rotate in opposite directions. Specifically, if the line connecting the accelerating/relaxing rolls 40 and the feed rolls 60 is taken as boundary line 70, then the feed rolls 60 and accelerating/relaxing rolls 40 whose rotational axes 47, 67 are on the same side of boundary line 70 rotate in the opposite direction to the rotational direction of the feed rolls 60.

In this case, the boundary line 70 is a straight line connecting the midpoint 68a of the line 68 connecting the rotational center axes 67 of the pair of feed rolls 60 and the midpoint 48a of the line 48 connecting the rotational center axes 47 of the pair of accelerating and relaxing rolls 40. The feed roll 60 and the accelerating and relaxing roll 40 have their rotational center axes 47, 67 located on the same side of the boundary line 70 defined in this way, and their rotation directions are opposite to each other.

In other words, in this embodiment, the rotational axis 47 of the first accelerating/relaxing roll 41 and the rotational axis 67 of the first feed roll 61 are located on the same side of the boundary line 70, and the rotational axis 47 of the second accelerating/relaxing roll 42 and the rotational axis 67 of the second feed roll 62 are located on the same side. Therefore, for the pair of accelerating/relaxing rolls 40 and the pair of feed rolls 60, the first accelerating/relaxing roll 41 and the first feed roll 61 rotate in opposite directions, and the second accelerating/relaxing roll 42 and the second feed roll 62 rotate in opposite directions.

<Guide roll 50>
The guide roll 50 is disposed between the speed-up/relaxation roll 40 and the feed roll 60 in the transport path 110 of the fiber bundle 105. The guide roll 50 is formed in a cylindrical shape, and the surface roughness of the outer circumferential surface is matte. The guide roll 50 is disposed so that the direction in which the rotation central axis extends is the first direction X, and is a free roll that can rotate around the rotation central axis in response to an externally input force. The guide roll 50 preferably has a diameter of approximately 30 mm to 100 mm.

The guide roll 50 is positioned between the speed-up relaxation roll 40 and the feed roll 60 on the transport path 110 of the fiber bundle 105, so that the fiber bundle 105 is looped around the guide roll 50 between the speed-up relaxation roll 40 and the feed roll 60 on the transport path 110 of the fiber bundle 105. In other words, the fiber bundle 105 is looped around the guide roll 50 at a position downstream of the second speed-up relaxation roll 42 of the pair of speed-up relaxation rolls 40, which is located relatively downstream on the transport path 110 of the fiber bundle 105.

In this embodiment, the guide roll 50 is positioned on the side of the boundary line 70, which is the line connecting the speed-up/relaxation rolls 40 and the feed rolls 60, where the second speed-up/relaxation roll 42 is located, and a portion of the outer circumferential surface of the guide roll 50 is positioned near the boundary line 70. Therefore, the guide roll 50 can position the fiber bundle 105 wound around the guide roll 50 in a position where it is transported along the boundary line 70 downstream of the guide roll 50 in the transport path 110 of the fiber bundle 105.

<Contact Range of Speed-Up Relaxation Roll 40 with Fiber Bundle 105>
A guide roll 50 is arranged downstream of the second speed-increasing relaxation roll 42, and a fiber-spreading bar 30 is arranged upstream of the first speed-increasing relaxation roll 41. The guide roll 50 and the fiber-spreading bar 30 are arranged at positions where the fiber bundle 105 can be brought into contact with the speed-increasing relaxation roll 40 over a range of at least half of the circumference of the speed-increasing relaxation roll 40.

In other words, the guide roll 50, which is located downstream of the second speed-up relaxation roll 42, is positioned so that a portion of its outer surface is located near the boundary line 70, which is the line connecting the speed-up relaxation rolls 40 and the feed rolls 60. Therefore, the guide roll 50 can bring the fiber bundle 105 wound around the second speed-up relaxation roll 42 into contact with the second speed-up relaxation roll 42 over as wide an area as possible in the circumferential direction of the second speed-up relaxation roll 42, in the downstream portion of the second speed-up relaxation roll 42. This allows the guide roll 50 to bring the fiber bundle 105 wound around the second speed-up relaxation roll 42 into contact with the second speed-up relaxation roll 42 over at least half of the circumferential direction of the second speed-up relaxation roll 42.

The fiber spreading bar 30 that can increase the contact area of the fiber bundle 105 on the first speed-up relaxation roll 41 is the fiber spreading bar 30 located most downstream on the conveying path 110 among the multiple fiber spreading bars 30 arranged upstream of the first speed-up relaxation roll 41. Of the multiple fiber spreading bars 30, the fiber spreading bar 30 located most downstream is arranged closer to the second speed-up relaxation roll 42 than the midpoint 48a of the line 48 connecting the rotational axes 47 of the pair of speed-up relaxation rolls 40, in a direction parallel to the line 48 connecting the rotational axes 47 of the pair of speed-up relaxation rolls 40. Therefore, the fiber spreading bar 30 can bring the fiber bundle 105 wound around the first speed-up relaxation roll 41 into contact with the first speed-up relaxation roll 41 over as wide an area as possible in the circumferential direction of the first speed-up relaxation roll 41 in the upstream portion of the first speed-up relaxation roll 41. This allows the fiber spreading bar 30 located most downstream to contact the fiber bundle 105 wound around the first speed-up relaxation roll 41 over at least half of the circumferential range of the first speed-up relaxation roll 41.

The most downstream spreading bar 30 of the multiple spreading bars 30 is preferably positioned so that it can contact the fiber bundle 105 over at least half of the circumferential range of the first speed-increasing relaxation roll 41, while being as close as possible to the first speed-increasing relaxation roll 41. By positioning the most downstream spreading bar 30 of the multiple spreading bars 30 as close as possible to the first speed-increasing relaxation roll 41, the fiber bundle 105 can be conveyed to the first speed-increasing relaxation roll 41 while maintaining the temperature of the fiber bundle 105, which has been increased by heating it with the spreading bar 30.

<Function of the fiber-spreading device 10>
The fiber-spreading device 10 according to this embodiment has the above-described configuration, and its operation will be described below. When the fiber-spreading device 10 spreads the fiber bundle 105, the roving 100 on which the fiber bundle 105 is wound into a cylindrical shape is attached to the unwinding machine 20, and the fiber bundle 105 is pulled out from the roving 100 and wound around the fiber-spreading bar 30, the speed-up relaxation roll 40, and the guide roll 50, and passed between the pair of feed rolls 60. In this way, the fiber bundle 105 is arranged along the transport path 110 for the fiber bundle 105.

In this state, the speed-up/relaxation roll 40 and the feed roll 60 are rotated. As a result, the fiber bundle 105 is sandwiched between the first feed roll 61 and the second feed roll 62, and as these feed rolls 60 rotate, the fiber bundle 105 is pulled from the upstream side to the downstream side of the conveying path 110. In other words, tension acts on the fiber bundle 105 in the direction from the upstream side to the downstream side of the conveying path 110. Due to the tension applied by the feed roll 60 in this manner, the fiber bundle 105 is continuously unwound from the unwinding machine 20 to which the roving 100 is attached.

In this case, the unwinder 20 is provided as a back tension roll that generates tension on the fiber bundle 105 in the direction opposite to the traveling direction of the fiber bundle 105. Therefore, the fiber bundle 105 unwound from the unwinder 20 due to the tension generated by the feed roll 60 is continuously unwound from the unwinder 20 while being applied tension from the unwinder 20 in the direction opposite to the tension applied by the feed roll 60. In other words, the fiber bundle 105 transported along the transport path 110 is transported under tension.

The tension acting on the fiber bundle 105 is thus generated by the force of the feed roll 60 pulling the fiber bundle 105 downstream and the tension applied to the fiber bundle 105 by the unwinding machine 20 in the opposite direction to the direction of travel of the fiber bundle 105. Therefore, the magnitude of the tension acting on the fiber bundle 105 can be adjusted by adjusting the strength of the tension exerted by the back tension roll of the unwinding machine 20.

The fiber bundle 105 unwound from the unwinder 20 first reaches the position of the fiber-spreading bar 30, which is located downstream of the unwinder 20, and comes into contact with the fiber-spreading bar 30. The fiber-spreading bar 30 is capable of being heated by passing a heat medium through it, so the fiber bundle 105 that comes into contact with the fiber-spreading bar 30 is heated by the heat transferred from the fiber-spreading bar 30. The fiber bundle 105 heated by the fiber-spreading bar 30 also heats the sizing agent that bundles the carbon fibers, causing the sizing agent to volatilize. This allows the carbon fibers that were bundled by the sizing agent to move freely, making the fiber bundle 105 more susceptible to deformation.

Furthermore, the fiber bundle 105 that comes into contact with the fiber spreading bar 30 changes its direction of travel at the position of the fiber spreading bar 30 as it is looped around the fiber spreading bar 30. On the other hand, because the fiber bundle 105 is transported while being tensioned, the fiber bundle 105, whose direction of travel changes at the position of the fiber spreading bar 30, is pressed against the fiber spreading bar 30. In other words, the fiber bundle 105 transported along the transport path 110 comes into contact with the fiber spreading bar 30, which is arranged in a non-rotatable state, and passes the position of the fiber spreading bar 30 while being pressed against the fiber spreading bar 30.

As a result, when the fiber bundle 105, whose carbon fibers are now more mobile, is pressed against the spreading bar 30, its shape deforms in the direction in which it is pressed against the spreading bar 30, for example, in the direction in which its thickness decreases in the radial direction of the rod-shaped spreading bar 30. In other words, the fiber bundle 105 deforms in the direction in which its width increases in the first direction X, and as a result, the fiber bundle 105 passing the position of the spreading bar 30 is spread by the spreading bar 30.

In addition, multiple spreading bars 30 are arranged, and the fiber bundle 105 is pressed against the multiple spreading bars 30 with different surfaces of the fiber bundle 105 in contact with them, passing through the position of the spreading bars 30. As a result, the fiber bundle 105 is heated from both surfaces that contact the spreading bars 30 and spread by being pressed against the spreading bars 30, resulting in balanced spreading. Note that in this embodiment, the multiple spreading bars 30 are arranged in a staggered pattern, but the arrangement of the spreading bars 30 is not limited to a regular arrangement such as a staggered arrangement and can be adjusted as appropriate as long as the fiber bundle 105 can be spread in a balanced manner.

The fiber bundle 105 opened by the opening bar 30 is transported along the transport path 110 and reaches the position of the speed-up relaxation roll 40. The speed-up relaxation roll 40 is a pair of rolls, a first speed-up relaxation roll 41 and a second speed-up relaxation roll 42, so the fiber bundle 105 reaches the position of the first speed-up relaxation roll 41, which is located relatively more upstream than the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42.

The speed-up/relaxation roll 40, which comes into contact with the fiber bundle 105 as it is wound around it, rotates at an increased peripheral speed within a range of 650% or less of the peripheral speed of the feed roll 60, and once the rotational speed reaches the set rotational speed, it maintains that speed and rotates at a constant speed. Meanwhile, because the fiber bundle 105 moves along the conveying path 110 due to the tension applied by the feed roll 60, the movement speed of the fiber bundle 105 is substantially the same as the peripheral speed of the feed roll 60.

For this reason, the speed-up relaxation roll 40, which rotates at a constant speed within a range where the peripheral speed is increased to 650% or less of the peripheral speed of the feed roll 60, rotates with its outer peripheral surface 44 sliding relative to the fiber bundle 105 wound around the speed-up relaxation roll 40. In other words, the first speed-up relaxation roll 41, around which the fiber bundle 105 transported from the fiber spreading bar 30 is wound, comes into contact with the fiber bundle 105 with its outer peripheral surface 44 sliding relative to the fiber bundle 105.

The force that the fiber bundle 105 receives from the first speed-up relaxation roll 41 as the first speed-up relaxation roll 41 slides in contact with the fiber bundle 105 acts on the fiber bundle 105 as a force pushing the fiber bundle 105 in the direction of travel along the transport path 110. As a result, the fiber bundle 105 wound around the first speed-up relaxation roll 41 is transported while being pushed slightly in the direction of travel along the transport path 110 by the first speed-up relaxation roll 41, which rotates at an increased peripheral speed within a range of 650% or less of the peripheral speed of the feed roll 60.

When the first acceleration relaxation roll 41 slides against the fiber bundle 105 and pushes the fiber bundle 105 in the direction of travel along the conveying path 110, the tension acting on the fiber bundle 105 decreases, causing the fiber bundle 105 to relax. In other words, the fiber bundle 105 is pulled by the feed roll 60 from the upstream side to the downstream side along the conveying path 110, and tension is applied by the unwinding machine 20 applying a force in the opposite direction to the direction in which the fiber bundle 105 is pulled by the feed roll 60. In other words, tension is applied to the fiber bundle 105 by the unwinding machine 20 applying a force in the opposite direction to the direction in which the fiber bundle 105 travels.

When the first speed-up relaxation roll 41 slides against and contacts the fiber bundle 105, pushing the fiber bundle 105 in the direction of travel, the force acting on the fiber bundle 105 in the direction opposite to the direction of travel of the fiber bundle 105 is reduced in the portion of the fiber bundle 105 looped around the first speed-up relaxation roll 41. As a result, the tension acting on the fiber bundle 105 is reduced in the portion of the fiber bundle 105 looped around the first speed-up relaxation roll 41, causing the fiber bundle 105 to relax. As the tension decreases, the fiber bundle 105 tends to increase in size in the direction perpendicular to the direction of tension.

In other words, when a large tension acts on the fiber bundle 105 in the extension direction of the fiber bundle 105, the tension causes the fiber bundle 105 to easily stretch in the extension direction, and as a result, the size of the fiber bundle 105 in the direction perpendicular to the extension direction tends to decrease. In this way, when the tension acting on the fiber bundle 105 is reduced, the fiber bundle 105 stretches less in the extension direction of the fiber bundle 105, which is the direction in which tension was acting, and since the reduced tension makes the fiber bundle 105 more likely to assume a free shape, the size of the fiber bundle 105 in the direction perpendicular to the extension direction, which tended to decrease when tension was acting, tends to increase.

The first speed-up relaxation roll 41, which slides against the fiber bundle 105 and pushes the fiber bundle 105 in the direction of travel along the transport path 110, reducing the tension of the fiber bundle 105, is capable of being heated by passing a heat medium through its interior. Therefore, the first speed-up relaxation roll 41 can heat the fiber bundle 105 it comes into contact with, and by volatilizing the sizing agent in the fiber bundle 105, it is possible to maintain a state in which the carbon fibers can move freely. This allows the first speed-up relaxation roll 41 to transport the fiber bundle 105 while maintaining a state in which the fiber bundle 105 is easily deformed.

In addition, in the portion of the fiber bundle 105 that is wound around the first speed-up relaxation roll 41, the direction of travel of the fiber bundle 105 is changed by the first speed-up relaxation roll 41, and the fiber bundle 105 is pressed against the first speed-up relaxation roll 41. This allows the carbon fibers to move freely, and the fiber bundle 105, which is more likely to assume a free shape compared to when tension is applied, deforms in the direction in which it is pressed against the first speed-up relaxation roll 41, i.e., in the direction in which its thickness in the radial direction of the first speed-up relaxation roll 41 decreases and its width in the first direction X increases.

As a result, the fiber bundle 105 passing the position of the first speed-up relaxation roll 41 while the tension is reduced due to the sliding contact of the first speed-up relaxation roll 41 is opened by the first speed-up relaxation roll 41. In other words, the tension of the fiber bundle 105 passing the position of the first speed-up relaxation roll 41 is reduced by the first speed-up relaxation roll 41, increasing the size freedom in the direction perpendicular to the direction in which the tension acts, and the width in the first direction X is increased by being pressed against the first speed-up relaxation roll 41, causing the fiber bundle to be opened.

In addition, in this embodiment, the fiber bundle 105 is wound around the first speed-up relaxation roll 41 by the most downstream spreading bar 30 among the multiple spreading bars 30, in a state where the fiber bundle 105 is in contact with the first speed-up relaxation roll 41 over a range of at least half the circumference of the first speed-up relaxation roll 41. As a result, the fiber bundle 105 comes into contact with the first speed-up relaxation roll 41 over a relatively long distance, and is heated over a long distance by the first speed-up relaxation roll 41, while the tension is reduced and the fiber is spread.

Because the second speed-up relaxation roll 42 is positioned downstream of the first speed-up relaxation roll 41, the fiber bundle 105 spread by the first speed-up relaxation roll 41 reaches the position of the second speed-up relaxation roll 42. Like the first speed-up relaxation roll 41, the second speed-up relaxation roll 42 also rotates at a constant speed, increasing its peripheral speed within a range of 650% or less of the peripheral speed of the feed roll 60, so the outer surface 44 of the second speed-up relaxation roll 42 also slides in contact with the fiber bundle 105. Therefore, the fiber bundle 105 wound around the second speed-up relaxation roll 42 is transported while being slightly pushed forward by the second speed-up relaxation roll 42 in the direction of travel along the transport path 110.

As a result, in the portion of the fiber bundle 105 that is wound around the second speed-up relaxation roll 42, the tension acting on the fiber bundle 105 is reduced, and the fiber bundle 105 relaxes, just like in the portion that is wound around the first speed-up relaxation roll 41. Similarly to the first speed-up relaxation roll 41, the second speed-up relaxation roll 42 can also be heated by passing a heat medium through its interior. Therefore, the second speed-up relaxation roll 42 can heat the fiber bundle 105 that it comes into contact with, and by volatilizing the sizing agent in the fiber bundle 105, it is possible to maintain a state in which the carbon fibers can move freely. This allows the second speed-up relaxation roll 42 to transport the fiber bundle 105 while maintaining a state in which the fiber bundle 105 is easily deformed.

Furthermore, in the portion of the fiber bundle 105 that is wound around the second speed-up relaxation roll 42, the direction of travel of the fiber bundle 105 is changed by the second speed-up relaxation roll 42, and the fiber bundle 105 is pressed against the second speed-up relaxation roll 42. Therefore, in the portion of the fiber bundle 105 that is wound around the second speed-up relaxation roll 42, the thickness in the radial direction of the second speed-up relaxation roll 42 becomes thinner, similar to the portion that is wound around the first speed-up relaxation roll 41, and the shape is deformed in a direction that increases the width in the first direction X.

As a result, the fiber bundle 105 passing the position of the second speed-up relaxation roll 42 while the tension is reduced due to sliding contact with the second speed-up relaxation roll 42 is opened by the second speed-up relaxation roll 42. In other words, the tension of the fiber bundle 105 passing the position of the second speed-up relaxation roll 42 is reduced by the second speed-up relaxation roll 42, increasing the size freedom in the direction perpendicular to the direction in which the tension acts, and the width in the first direction X is increased by being pressed against the second speed-up relaxation roll 42, causing the fiber bundle to be opened.

In addition, in this embodiment, the fiber bundle 105 is wound around the second speed-up relaxation roll 42 by the guide roll 50 in a state where it is in contact with the second speed-up relaxation roll 42 over a range of at least half of the circumference of the second speed-up relaxation roll 42. As a result, the fiber bundle 105 is in contact with the second speed-up relaxation roll 42 over a relatively long distance, and is heated by the second speed-up relaxation roll 42 over a long distance while the tension is reduced and the fiber is spread.

Furthermore, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42, which spread the fiber bundle 105 in this manner, each come into contact with the fiber bundle 105 on different surfaces. Therefore, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 heat the fiber bundle 105 from different surfaces while pressing the first speed-up relaxation roll 41 or the second speed-up relaxation roll 42 against the fiber bundle 105 to spread it, allowing for well-balanced spreading.

As described above, the speed-up relaxation roll 40 reduces the tension of the fiber bundle 105 by sliding against it and spreading it, so the rotational speed of the speed-up relaxation roll 40 is preferably set according to the required spread width of the fiber bundle 105. In other words, the rotational speed of the speed-up relaxation roll 40 is preferably set according to the required spread width of the fiber bundle 105, at a rotational speed that increases the peripheral speed within a range that is 650% or less of the peripheral speed of the feed roll 60.

In addition, the temperature of the speed-up relaxation roll 40 when heating the fiber bundle 105 is preferably adjusted according to the thermal decomposition temperature of the sizing agent used in the fiber bundle 105 or the amount of sizing agent desired to be thermally decomposed.

The fiber bundle 105 spread by the speed-up/relaxation roll 40 is transported along the transport path 110 and reaches the position of the guide roll 50, which is located downstream of the speed-up/relaxation roll 40. The fiber bundle 105 is looped around the guide roll 50, which changes its direction of travel. However, because the guide roll 50 is a free roll, the fiber bundle 105 that has reached the position of the guide roll 50 smoothly changes its direction of travel as the guide roll 50 rotates in conjunction with the movement of the fiber bundle 105.

The fiber bundle 105, whose direction of travel is changed by the guide roll 50, has its direction of travel changed so that it faces the area between the first feed roll 61 and the second feed roll 62. In other words, the fiber bundle 105 wound around the guide roll 50 has its direction of travel changed by the guide roll 50 to a direction perpendicular to the line 68 connecting the rotational center axes 67 of the pair of feed rolls 60.

The fiber bundle 105, whose direction of travel has been changed by the guide roll 50, reaches the position of the feed roll 60, which is located downstream of the guide roll 50. Because the fiber bundle 105's direction of travel has been changed by the guide roll 50, the fiber bundle 105 that reaches the position of the feed roll 60 reaches the portion between the first feed roll 61 and the second feed roll 62 of the feed roll 60. As a result, the fiber bundle 105 comes into contact with the first feed roll 61 and the second feed roll 62 almost simultaneously, and moves downstream of the fiber spreader 10 while being sandwiched between the rotating first feed roll 61 and second feed roll 62. The fiber spreader 10 spreads the fiber bundle 105 in this way, and transports the spread fiber bundle 105 to a process downstream of the fiber spreader 10.

<Effects of the embodiment>
The fiber-spreading device 10 according to the above embodiment includes the speed-up relaxation roll 40 that rotates at an increased peripheral speed within a range of 650% or less of the peripheral speed of the feed roll 60 and comes into contact with the fiber bundle 105, and therefore can spread the fiber bundle 105 while reducing the tension of the fiber bundle 105 with the speed-up relaxation roll 40. Furthermore, the speed-up relaxation roll 40 includes the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 that comes into contact with a surface of the fiber bundle 105 different from the surface that comes into contact with the first speed-up relaxation roll 41, and therefore can spread the fiber bundle 105 in a balanced manner from both sides of the fiber bundle 105. As a result, the fiber bundle 105 that is spread to a wide width can be stably obtained.

Furthermore, the feed roll 60 and the speed-up relaxation roll 40 located on the same side of the boundary line 70 connecting the midpoint 68a of the line 68 connecting the rotational center axes 67 of the pair of feed rolls 60 and the midpoint 48a of the line 48 connecting the rotational center axes 47 of the pair of speed-up relaxation rolls 40 rotate in opposite directions. Therefore, the speed-up relaxation roll 40, which applies a force to the fiber bundle 105 in a direction that reduces the tension, can be positioned efficiently. As a result, the overall size of the fiber-spreading device 10, which can stably produce a wide-spread fiber bundle 105, can be reduced.

In addition, because the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are positioned at a predetermined distance, the fiber bundle 105 can be transported from the first speed-up relaxation roll 41 to the second speed-up relaxation roll 42 without being pinched between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42. This allows the tension of the fiber bundle 105 to be reduced by each of the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42, thereby spreading the fiber bundle 105. As a result, a wide-spread fiber bundle 105 can be stably obtained.

In addition, because the guide roll 50 is positioned between the speed-up and speed-down roll 40 and the feed roll 60 on the transport path 110 of the fiber bundle 105, the fiber bundle 105 can be properly guided to the section between the first feed roll 61 and the second feed roll 62 relative to the feed roll 60. This allows the fiber bundle 105 to be properly sandwiched between the first feed roll 61 and the second feed roll 62, and tension can be applied to the fiber bundle 105. Therefore, the fiber bundle 105 can be moved from the upstream side to the downstream side in the transport direction of the transport path 110, and by applying tension to the fiber bundle 105, a force can be generated that presses the fiber bundle 105 against the spreading bar 30 and the speed-up and speed-down roll 40, promoting the spreading of the fiber bundle 105. As a result, a wide-spread fiber bundle 105 can be reliably obtained.

In addition, the spreading bar 30 located most downstream on the conveying path 110 is positioned closer to the second speed-up relaxation roll 42 than the midpoint 48a of the line 48 connecting the rotational center axes 47 of the pair of speed-up relaxation rolls 40 in a direction parallel to the line 48. This allows the fiber bundle 105 wound around the first speed-up relaxation roll 41 to come into contact with the first speed-up relaxation roll 41 over a range of at least half the circumference of the first speed-up relaxation roll 41. This allows the fiber bundle 105 wound around the first speed-up relaxation roll 41 to come into contact with the first speed-up relaxation roll 41 over a relatively long distance, allowing the first speed-up relaxation roll 41 to heat the fiber bundle 105 over a long distance while reducing tension and spreading it. As a result, a wide-spread fiber bundle 105 can be reliably obtained.

Furthermore, when the speed-up relaxation roll 40 is viewed in a direction along the central axis 47 of rotation of the speed-up relaxation roll 40, the fiber bundle 105 is wound around the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 in an S-shape or an inverted S-shape, so that the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 can efficiently contact different surfaces of the fiber bundle 105. In other words, by winding the fiber bundle 105 around the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 in an S-shape or an inverted S-shape, the second speed-up relaxation roll 42 can contact the surface of the fiber bundle 105 opposite the surface that contacted the first speed-up relaxation roll 41, downstream immediately after the first speed-up relaxation roll 41 contacts the fiber bundle 105. This allows the transport path 110 of the fiber bundle 105 to be shortened when the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are brought into contact with different sides of the fiber bundle 105, thereby making it possible to reduce the size of the area around the speed-up relaxation roll 40. As a result, the overall size of the fiber spreading device 10, which can stably produce a wide-spread fiber bundle 105, can be reduced.

In addition, because the surfaces of the opening bar 30, the speed-up and relaxation roll 40, and the second feed roll 62 have a matte finish, surface friction can be reduced compared to when the surfaces are plated. This reduces the occurrence of fuzzing in the fiber bundle 105. In other words, if the surfaces of the opening bar 30, the speed-up and relaxation roll 40, and the second feed roll 62 are plated, the surfaces become flat, and the contact area of the fiber bundle 105 increases when it comes into contact with them. In this case, the frictional force between these components and the fiber bundle 105 increases, and when the fiber bundle 105 is pressed against these components, the large frictional force may make fuzzing more likely to occur on the surface of the fiber bundle 105.

In contrast, if the surface roughness of the fiber spreading bar 30, the speed-up relaxation roll 40, and the second feed roll 62 is matte, the contact area between these components and the fiber bundle 105 can be reduced. This reduces the friction between the fiber spreading bar 30, the speed-up relaxation roll 40, and the second feed roll 62 and the fiber bundle 105, and suppresses the generation of fluff in the fiber bundle 105. As a result, a wide-spread fiber bundle 105 can be reliably obtained.

Furthermore, by setting the distance between the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 as close as possible, at approximately 1 mm to 50 mm, when the fiber bundle 105 is transported from the first speed-up relaxation roll 41 to the second speed-up relaxation roll 42, the temperature of the fiber bundle 105 heated by the first speed-up relaxation roll 41 can be maintained while transporting it to the second speed-up relaxation roll 42. As a result, when the fiber bundle 105 is spread by the second speed-up relaxation roll 42, the sizing agent in the fiber bundle 105 volatilizes, allowing the fiber bundle 105 to be spread in a state that is easily deformed. As a result, a wide-spread fiber bundle 105 can be reliably obtained.

In addition, in the fiber-spreading method according to the embodiment, the speed-up relaxation roll 40, which rotates at an increased speed within a range of 650% or less of the peripheral speed of the feed roll 60, is brought into contact with the fiber bundle 105, so that the tension in the fiber bundle 105 can be reduced by the speed-up relaxation roll 40 while the fiber bundle 105 is being spread. Furthermore, because different surfaces of the fiber bundle 105 contact the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42, the fiber bundle 105 can be spread from both sides of the fiber bundle 105 in a balanced manner. As a result, a wide-spread fiber bundle 105 can be stably obtained.

In addition, because the speed-up relaxation roll 40 increases its peripheral speed within a range of 200% to 650% of the peripheral speed of the feed roll 60, the speed-up relaxation roll 40 can open the fiber bundle 105 while suppressing defects in the fiber bundle 105 upstream of the speed-up relaxation roll 40. In other words, if the peripheral speed of the speed-up relaxation roll 40 is less than 200% of the peripheral speed of the feed roll 60, the peripheral speed of the speed-up relaxation roll 40 is too slow, which may make it difficult for the speed-up relaxation roll 40 to effectively reduce the tension of the fiber bundle 105 wound around the speed-up relaxation roll 40. In this case, it may be difficult for the speed-up relaxation roll 40 to effectively open the fiber bundle 105. Furthermore, if the peripheral speed of the speed-up relaxation roll 40 exceeds 650% of the peripheral speed of the feed roll 60, the peripheral speed of the speed-up relaxation roll 40 will be too fast, and the force exerted by the speed-up relaxation roll 40 in the direction of travel of the fiber bundle 105 may become too great. In this case, the tension in the fiber bundle 105 upstream of the speed-up relaxation roll 40 may become too great, and the large tension may press the fiber bundle 105 against the spreading bar 30 with a large force, which may result in problems such as the generation of fluff on the surface of the fiber bundle 105 that contacts the spreading bar 30.

In contrast, if the speed-up relaxation roll 40 is increased in a range of 200% to 650% of the peripheral speed of the feed roll 60, the tension of the fiber bundle 105 wound around the speed-up relaxation roll 40 can be effectively reduced while preventing the tension of the fiber bundle 105 from becoming too high upstream of the speed-up relaxation roll 40. This allows the fiber bundle 105 to be spread by the speed-up relaxation roll 40 while suppressing problems such as fuzzing of the fiber bundle 105 upstream of the speed-up relaxation roll 40. As a result, a widely spread fiber bundle 105 can be reliably obtained.

[Modification]
In the spreading device 10 according to the above-described embodiment, an example of the arrangement of the spreading bars 30, the speed-up and relaxation rolls 40, the guide rolls 50, and the feed rolls 60 has been described, but these arrangements may be arrangements other than those in the above-described embodiment.

Figure 2 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which the first speed-up relaxation roll 41 is arranged below the second speed-up relaxation roll 42. For example, as shown in Figure 2, the speed-up relaxation roll 40 may be arranged such that the first speed-up relaxation roll 41 is arranged below the second speed-up relaxation roll 42 in the third direction Z, and the second speed-up relaxation roll 42 is arranged above the first speed-up relaxation roll 41. In this case, the fiber bundle 105 transported from the most downstream fiber-spreading bar 30 among the multiple fiber-spreading bars 30 to the speed-up relaxation roll 40 is transported to the first speed-up relaxation roll 41, which is located relatively lower among the pair of speed-up relaxation rolls 40.

Furthermore, the fiber bundle 105 transported to the first speed-up relaxation roll 41 is transported from the first speed-up relaxation roll 41 to the second speed-up relaxation roll 42 located above it, and then transported from the second speed-up relaxation roll 42 toward the guide roll 50. In this way, the pair of speed-up relaxation rolls 40 only needs to be configured so that the fiber bundle 105 is transported from the opening bar 30 to the first speed-up relaxation roll 41 and from the first speed-up relaxation roll 41 to the second speed-up relaxation roll 42, regardless of the relative vertical positions of the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42.

In addition, the drive motor 45 that supplies driving force to the speed-up relaxation roll 40 may be connected to the first speed-up relaxation roll 41, as shown in FIG. 2. In this case, the driving force generated by the drive motor 45 is transmitted to the first speed-up relaxation roll 41, and the driving force transmitted to the first speed-up relaxation roll 41 is transmitted to the second speed-up relaxation roll 42 via a power transmission mechanism. As a result, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 each rotate around their respective rotation center axes 47 due to the driving force transmitted from the drive motor 45.

In addition, in the above-described embodiment, the pair of feed rolls 60 are arranged side by side in the third direction Z, but the direction in which the pair of feed rolls 60 are arranged may be a direction other than the third direction Z. Figure 3 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which the pair of feed rolls 60 are arranged side by side in the second direction Y. Figure 4 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which the pair of feed rolls 60 are arranged side by side in the second direction Y. The pair of feed rolls 60 may be, for example, a first feed roll 61 and a second feed roll 62 arranged side by side in the second direction Y, as shown in Figures 3 and 4. In this case, the first feed roll 61 and the second feed roll 62 sandwich the fiber bundle 105 from both sides in the second direction Y and transport it in the third direction Z. Therefore, the fiber bundle 105 transported from the guide roll 50 toward the feed roll 60 is transported along the third direction Z so that the fiber bundle 105 can be sandwiched between the pair of feed rolls 60 on both sides in the second direction Y.

In the modified example shown in Figures 3 and 4, the guide roll 50 is positioned above the feed roll 60 in the third direction Z, and the fiber bundle 105 transported from the guide roll 50 toward the feed roll 60 is transported from above in the third direction Z toward the feed roll 60. As a result, the feed roll 60 transports the fiber bundle 105, which has been spread by the spreading bar 30 and the speed-up relaxation roll 40, toward the bottom in the third direction Z.

Furthermore, when the first feed roll 61 and the second feed roll 62 are arranged side by side in the second direction Y, the speed-up and relaxation rolls 40 may be arranged such that the first speed-up and relaxation roll 41 is arranged on the upper side and the second speed-up and relaxation roll 42 is arranged on the lower side, as shown in Figure 3, or the first speed-up and relaxation roll 41 is arranged on the lower side and the second speed-up and relaxation roll 42 is arranged on the upper side, as shown in Figure 4.

In addition, in the above-described embodiment, the pair of speed-up relaxation rolls 40 are arranged side by side in the third direction Z, but the direction in which the pair of speed-up relaxation rolls 40 are arranged side by side may be a direction other than the third direction Z. Figure 5 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which the pair of speed-up relaxation rolls 40 are arranged side by side in the second direction Y. Figure 6 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which the pair of speed-up relaxation rolls 40 are arranged side by side in the second direction Y. The pair of speed-up relaxation rolls 40 may be, for example, a first speed-up relaxation roll 41 and a second speed-up relaxation roll 42 arranged side by side in the second direction Y, as shown in Figures 5 and 6.

In this case, the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 may be arranged, for example, as shown in FIG. 5, such that the first speed-up relaxation roll 41, to which the fiber bundle 105 is transported from the fiber spreading bar 30, is positioned closer to the feed roll 60 in the second direction Y, and the second speed-up relaxation roll 42, located downstream of the first speed-up relaxation roll 41, is positioned closer to the unwinder 20 in the second direction Y. Alternatively, as shown in FIG. 6, the first speed-up relaxation roll 41, to which the fiber bundle 105 is transported from the fiber spreading bar 30, is positioned closer to the unwinder 20 in the second direction Y, and the second speed-up relaxation roll 42, located downstream of the first speed-up relaxation roll 41, is positioned closer to the feed roll 60 in the second direction Y.

Furthermore, both the direction in which the pair of speed-up relaxation rolls 40 are aligned and the direction in which the pair of feed rolls 60 are aligned may be directions other than the third direction Z. Figure 7 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which a pair of speed-up relaxation rolls 40 and a pair of feed rolls 60 are aligned in the second direction Y. Figure 8 is a schematic diagram showing a modified example of the fiber-spreading device 10 according to the embodiment, in which a pair of speed-up relaxation rolls 40 and a pair of feed rolls 60 are aligned in the second direction Y. As shown in Figures 7 and 8, the direction in which the pair of speed-up relaxation rolls 40 and the pair of feed rolls 60 are aligned may be such that the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are aligned in the second direction Y, and the first feed roll 61 and the second feed roll 62 are aligned in the second direction Y.

In this case, as shown in FIG. 7, the first speed-up relaxation roll 41, to which the fiber bundle 105 is transported from the fiber spreading bar 30, may be positioned on the opposite side of the unwinder 20 in the second direction Y, and the second speed-up relaxation roll 42, which is positioned downstream of the first speed-up relaxation roll 41, may be positioned closer to the unwinder 20 in the second direction Y. Alternatively, as shown in FIG. 8, the first speed-up relaxation roll 41, to which the fiber bundle 105 is transported from the fiber spreading bar 30, may be positioned closer to the unwinder 20 in the second direction Y, and the second speed-up relaxation roll 42, which is positioned downstream of the first speed-up relaxation roll 41, may be positioned on the opposite side of the unwinder 20 in the second direction Y.

As such, the arrangement of the opening bar 30, speed-up/relaxation roll 40, guide roll 50, and feed roll 60 may be other than that described in the above embodiment, and it is preferable that the arrangement be set appropriately based on the location where the opening device 10 is placed, the environment in which it is placed, etc.

In addition, in the above-described embodiment, the speed-up relaxation roll 40 is configured such that the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are connected via a power transmission mechanism, and both the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42 are rotated by the driving force generated by a single drive motor 45. However, a drive motor 45 may be provided for each of the first speed-up relaxation roll 41 and the second speed-up relaxation roll 42.

Similarly, the feed roll 60 has a first feed roll 61 and a second feed roll 62 connected via a power transmission mechanism, and both the first feed roll 61 and the second feed roll 62 are rotated by the driving force generated by a single drive motor 65, but a drive motor 65 may be provided for each of the first feed roll 61 and the second feed roll 62.

In addition, in the above-described embodiment, two speed-up relaxation rolls 40, a first speed-up relaxation roll 41 and a second speed-up relaxation roll 42, are used, but the number of speed-up relaxation rolls 40 may be other than two, and there may be three or more speed-up relaxation rolls 40. The number of speed-up relaxation rolls 40, which rotate at a circumferential speed increased relative to the circumferential speed of the feed roll 60, is not limited as long as it is two or more.

In addition, although three fiber-spreading bars 30 are provided in the above-described embodiment, the number of fiber-spreading bars 30 may be other than three. It is preferable to determine the number of fiber-spreading bars 30 to be arranged depending on the tension applied to the fiber bundle 105, the contact angle of the fiber bundle 105 with the fiber-spreading bars 30 when the fiber bundle 105 is wound around the fiber-spreading bars 30, the heating time of the fiber bundle 105 by the fiber-spreading bars 30, etc.

In addition, in the above-described embodiment, the tension acting on the fiber bundle 105 is adjusted by adjusting the strength of the tension applied by the back tension roll of the unwinding machine 20, but the tension acting on the fiber bundle 105 may also be adjusted by other methods. The tension acting on the fiber bundle 105 may also be adjusted by, for example, changing the number of fiber-spreading bars 30, the diameter of the fiber-spreading bars 30, the angle at which the fiber bundle 105 is wound around the fiber-spreading bars 30, etc.

<Test of Spreading of Fiber Bundle 105 by Spreading Device 10>
The inventors conducted a test on the amount of fiber spreading when the fiber bundle 105 is spread by the fiber spreading device 10. Next, an evaluation test on the relationship between the circumferential speed of the speed-up relaxation roll 40 relative to the circumferential speed of the feed roll 60 and the amount of fiber spreading of the fiber bundle 105 will be described.

Figure 9 is a schematic diagram showing the device configuration of the fiber-spreading device 10 used in the evaluation test. The evaluation test for the spread amount of the fiber bundle 105 was conducted using a fiber-spreading device 10 as shown in Figure 9, which has five fiber-spreading bars 30, a first speed-up relaxation roll 41 and a second speed-up relaxation roll 42 arranged side by side in the second direction Y, and a first feed roll 61 and a second feed roll 62 arranged side by side in the second direction Y. The evaluation test used a carbon fiber tow TR50S15L (15,000 filaments, 7 μm filament diameter) manufactured by Mitsubishi Chemical Corporation as the fiber bundle 105. Multiple fiber bundles 105 were attached to the fiber-spreading device 10 shown in Figure 9, and the spread state of the fiber bundles 105 was evaluated when the fiber bundles 105 were spread by the fiber-spreading device 10.

The evaluation test for the amount of fiber spread of the fiber bundle 105 was conducted by setting the conveying speed of the fiber bundle 105 in the fiber spread device 10 to 5 m/min and varying the peripheral speed of the speed-up relaxation roll 40 relative to the peripheral speed of the feed roll 60 to spread the fiber bundle 105. The evaluation test was conducted by measuring the amount of fiber spread of the fiber bundle 105 and the tension of the fiber bundle 105 when the fiber bundle 105 was spread by the fiber spread device 10 in this way, and determining whether or not fluff occurred in the fiber bundle 105.

Figure 10 is a chart showing the results of the evaluation test. Regarding the spread amount of the fiber bundle 105, the position where the fiber bundle 105 is wound around the first speed-increasing relaxation roll 41 is defined as the first spread width measurement position S1, and the position where the fiber bundle 105 is wound around the second speed-increasing relaxation roll 42 is defined as the second spread width measurement position S2, and the spread width of the fiber bundle 105 in the first direction X is measured at each position. The value obtained by subtracting the spread width of the fiber bundle 105 at the first spread width measurement position S1 from the spread width of the fiber bundle 105 measured in this way at the second spread width measurement position S2 is defined as the spread amount of the fiber bundle 105 spread by the speed-increasing relaxation roll 40 in this evaluation test.

The tension of the fiber bundle 105 is measured at each of the following positions using a handheld tension meter: the position between the opening bar 30 and the first speed-increasing relaxation roll 41 on the conveying path 110 of the fiber bundle 105 is designated as the first tension measurement position T1; and the position between the guide roll 50 and the feed roll 60 is designated as the second tension measurement position T2. The tension of the fiber bundle 105 measured in this way at the first tension measurement position T1 minus the tension of the fiber bundle 105 at the second tension measurement position T2 is defined as the tension of the fiber bundle 105 reduced by the speed-increasing relaxation roll 40.

The opening amount of the fiber bundle 105 measured in this manner was evaluated by calculating the average opening amount of three of the multiple fiber bundles 105 attached to the fiber spreading device 10, i.e., the average opening amount of the three pass lines. The tension difference of the fiber bundle 105 was also evaluated by calculating the average tension difference of the three pass lines.

The presence or absence of fluffing in the fiber bundle 105 was determined by visually inspecting the fiber bundle 105 that had passed through the fiber-spreading bar 30 during fiber-spreading using the fiber-spreading device 10.

These evaluation tests were conducted under nine conditions: Examples 1 to 6, which differ in the peripheral speed ratio (the ratio of the peripheral speed of the acceleration/relaxation roll 40 to the peripheral speed of the feed roll 60), and Comparative Examples 1 to 3, which are compared to these Examples. Of these, Example 1 had a peripheral speed ratio (the ratio of the peripheral speed of the acceleration/relaxation roll 40 to the peripheral speed of the feed roll 60) of 150%, Example 2 had a peripheral speed ratio of 200%, Example 3 had a peripheral speed ratio of 250%, Example 4 had a peripheral speed ratio of 400%, Example 5 had a peripheral speed ratio of 600%, and Example 6 had a peripheral speed ratio of 650%. In contrast, Comparative Example 1 had a peripheral speed ratio of 50%, Comparative Example 2 had a peripheral speed ratio of 100%, and Comparative Example 3 had a peripheral speed ratio of 700%.

As a result of conducting a test to spread the fiber bundle 105 under these conditions, the results shown in Figure 10 were obtained for the amount of spreading of the fiber bundle 105, the difference in tension of the fiber bundle 105, and whether or not fluffing occurred in the fiber bundle 105 at the spreading bar 30.

That is, when the peripheral speed of the accelerating/relaxing roll 40 is low relative to the peripheral speed of the feed roll 60, as in Comparative Example 1, or when the peripheral speeds are the same as those of the feed roll 60, as in Comparative Example 2, it is difficult to reduce the tension of the fiber bundle 105 using the accelerating/relaxing roll 40, making it difficult to effectively increase the amount of fiber spreading of the fiber bundle 105. Furthermore, when the peripheral speed of the accelerating/relaxing roll 40 exceeds 650% relative to the peripheral speed of the feed roll 60, as in Comparative Example 3, the peripheral speed of the accelerating/relaxing roll 40 is too fast relative to the peripheral speed of the feed roll 60, and there is a risk that the tension of the fiber bundle 105 upstream of the accelerating/relaxing roll 40 will become too great. In this case, the fiber bundle 105 rubs against the spreading bar 30 with great force as it passes through the spreading bar 30, making it more likely that fuzz will occur at the spreading bar 30.

In contrast, as in Examples 1 to 6, when the peripheral speed of the accelerating/relaxing rolls 40 is increased within a range of 650% or less relative to the peripheral speed of the feed rolls 60, the tension in the fiber bundle 105 can be effectively reduced by the accelerating/relaxing rolls 40, and it was confirmed that the amount of fiber spreading of the fiber bundle 105 can be increased by the accelerating/relaxing rolls 40. In other words, in this test, a pair of accelerating/relaxing rolls 40 was placed between the spreading bar 30 and the feed rolls 60 on the conveying path 110, and the accelerating/relaxing rolls 40 were rotated at an increased peripheral speed within a range of 650% or less relative to the peripheral speed of the feed rolls 60, thereby confirming that a widely spread fiber bundle 105 can be stably obtained.

10...spreading device, 20...unwinder, 30...spreading bar, 40...accelerating relaxation roll, 41...first accelerating relaxation roll, 42...second accelerating relaxation roll, 44...outer surface, 45...drive motor, 47...rotation center shaft, 50...guide roll, 60...feed roll, 61...first feed roll, 62...second feed roll, 64...outer surface, 65...drive motor, 66...air cylinder, 67...rotation center shaft, 70...boundary line, 100...roving, 105...fiber bundle, 110...conveying path

Claims (7)

a payout machine that continuously pays out a long fiber bundle obtained by bundling carbon fibers with a sizing agent;
a pair of feed rolls each formed in a cylindrical shape, which rotate in opposite directions while sandwiching the fiber bundle unwound from the unwinder between them, thereby transporting the fiber bundle downstream in a transport path of the fiber bundle;
a plurality of spreading bars formed in a rod shape and arranged in the conveying path between the unwinder and the feed roll, the plurality of spreading bars being arranged at positions where they alternately come into contact with different surfaces of the fiber bundle as they move from the upstream side to the downstream side of the conveying path;
a pair of speed-increasing relaxation rolls each formed in a cylindrical shape and disposed between the fiber-spreading bar and the feed roll in the transport path, rotating at a peripheral speed increased within a range of 650% or less of the peripheral speed of the feed roll, and having outer circumferential surfaces in contact with the fiber bundle;
Equipped with
The pair of speed-increasing relaxation rolls are
a first speed-increasing relaxation roll disposed downstream of the fiber-spreading bar in the conveying path;
a second speed-increasing relaxation roll that is disposed between the first speed-increasing relaxation roll and the feed roll in the transport path and that comes into contact with a surface of the fiber bundle different from a surface that comes into contact with the first speed-increasing relaxation roll,
When the speed-increasing relaxation roll is viewed in a direction along the rotation center axis of the speed-increasing relaxation roll, the fiber bundle is wound around the first speed-increasing relaxation roll and the second speed-increasing relaxation roll in an S-shape or an inverted S-shape, so that the first speed-increasing relaxation roll and the second speed-increasing relaxation roll come into contact with different surfaces of the fiber bundle ,
the pair of speed-up relaxation rolls are each in contact with the fiber bundle over a range of at least half of the circumferential direction of the speed-up relaxation roll,
A drive motor is connected to the second speed-up relaxation roll,
the first speed-up relaxation roll and the second speed-up relaxation roll are connected via a power transmission mechanism, and a driving force transmitted from the drive motor to the second speed-up relaxation roll is transmitted to the first speed-up relaxation roll via the power transmission mechanism . The fiber-spreading device described in claim 1, wherein when the feed roll and the speed-up/relaxation roll are viewed in a direction along the central axes of rotation of the feed roll and the speed-up/relaxation roll, the feed roll and the speed-up/relaxation roll whose central axes of rotation are on the same side of a boundary line defined by a straight line connecting the midpoint of a line connecting the central axes of rotation of each of the pair of feed rolls and the midpoint of a line connecting the central axes of rotation of each of the pair of speed-up/relaxation rolls are such that the rotation direction of the speed-up/relaxation roll is opposite to the rotation direction of the feed roll. A fiber-spreading device according to claim 1 or 2, wherein the first speed-increasing relaxation roll and the second speed-increasing relaxation roll are arranged at a predetermined distance. The fiber-spreading device described in any one of claims 1 to 3 includes a guide roll formed in a cylindrical shape and positioned between the speed-up/relaxation roll and the feed roll in the conveying path. A fiber-spreading device according to any one of claims 1 to 4, wherein the fiber-spreading bar located furthest downstream in the conveying path is positioned closer to the second speed-up relaxation roll than the midpoint of the line connecting the rotational axes of the pair of speed-up relaxation rolls in a direction parallel to the line connecting the rotational axes of the pair of speed-up relaxation rolls. a fiber-spreading method comprising: continuously unwinding a long fiber bundle obtained by bundling carbon fibers with a sizing agent from a unwinding machine; sandwiching the fiber bundle unwound from the unwinding machine between a pair of feed rolls rotating in opposite directions and transporting the fiber bundle downstream in a transport path of the fiber bundle; and alternately bringing different surfaces of the fiber bundle into contact with a plurality of rod-shaped fiber-spreading bars arranged between the unwinding machine and the feed rolls in the transport path as the fiber bundle moves from the upstream side to the downstream side in the transport path, thereby spreading the fiber bundle;
a first speed-increasing relaxation roll disposed downstream of the fiber-spreading bar in the conveying path, the first speed-increasing relaxation roll being cylindrical and rotating at a peripheral speed that is 650% or less of the peripheral speed of the feed roll; and a second speed-increasing relaxation roll disposed between the first speed-increasing relaxation roll and the feed roll in the conveying path , the first speed-increasing relaxation roll and the second speed-increasing relaxation roll being connected to each other via a power transmission mechanism, and the fiber bundle is brought into contact with outer peripheral surfaces of the pair of speed-increasing relaxation rolls, the drive force of a drive motor being transmitted to the second speed-increasing relaxation roll being transmitted to the first speed-increasing relaxation roll via the power transmission mechanism ,
a fiber-spreading method in which the fiber bundle is wound around the first speed-up relaxation roll and the second speed-up relaxation roll in an S-shape or an inverted S-shape when the speed-up relaxation rolls are viewed in a direction along the central axis of rotation of the speed-up relaxation roll, so that different surfaces of the fiber bundle come into contact with the first speed-up relaxation roll and the second speed-up relaxation roll, and the fiber bundle comes into contact with each of the pair of speed-up relaxation rolls over a range of at least half of the circumference of each of the speed-up relaxation rolls . The fiber-spreading method described in claim 6, wherein the speed-up/relaxation roll increases its peripheral speed within a range of 200% to 650% of the peripheral speed of the feed roll.