Abstract: A production method of a carbon fiber precursor fiber and/or a fiber bundle which permits easy bundling of a plurality of small tows into one bundle, with a dividing capability to divide into the original small tows spontaneously at the time of firing, and is suitable for obtaining a carbon fiber that is excellent in productivity and quality. A production method of carbon fiber precursor fiber and/or a fiber bundle that has a degree of intermingle of 1 m?1 or less between small tows, consists of substantially straight fibers without imparted crimp, a tow of which straight fibers has a moisture content of less than 10% by mass when housed in a container, and has a widthwise dividing capability to maintain a form of a single aggregate of tows when housed in a container, taken out from the container and guided into a firing step, and to divide into a plurality of small tows in the firing step by the tension generated in the firing step.

Abstract: There are provided a carbon fiber precursor fiber bundle which permits easy bundling of a plurality of small tows into one bundle, is provided with a dividing capability to divide into the original small tows spontaneously at the time of firing, and is suitable for obtaining a carbon fiber that is excellent in productivity and quality, and a production method and a production apparatus of the carbon fiber precursor fiber bundle, and an excellent carbon fiber and a production method thereof. A production apparatus of a carbon fiber precursor fiber bundle, comprising an intermingling device that comprises a yarn channel having a flat rectangular section through which a plurality of small tows can pass in a manner adjacent to each other and a plurality of air jet holes disposed with predetermined intervals along the long side direction of the flat rectangle and having the openings thereof in the yarn channel.

Abstract: There are provided a carbon fiber precursor fiber bundle which permits easy bundling of a plurality of small tows into one bundle, is provided with a dividing capability to divide into the original small tows spontaneously at the time of firing, and is suitable for obtaining a carbon fiber that is excellent in productivity and quality, and a production method and a production apparatus of the carbon fiber precursor fiber bundle, and an excellent carbon fiber and a production method thereof.

Abstract: A production device and production method for carbon fibers of the present invention is utilized to reliably obtain a connecting portion having a high process passing property with a simple mechanism so as to achieve a continuous operation and improve a firing process operability for achieving a low cost. A pair of yarn gripping devices for overlaying precursor fiber yarns to be connected one upon another and gripping the overlaid ends is provided, and a fluid processing unit for applying an entangling process by jetting a plurality of rows of fluid in along a yarn length direction is provided between the pair of yarn gripping devices. A plurality of discontinuous thread handling areas of the precursor fiber yarns in a fluid jet area of the fluid processing unit having fluid jet holes are disposed at predetermined intervals.

Abstract: An object of a production device and production method for carbon fibers of the present invention is to certainly obtain a connecting portion having a high process passing property with a simple mechanism so as to achieve a continuous operation and improve a firing process operability for achieving a low cost.