Abstract: A method for manufacturing a carbon fiber bundle includes a stabilization process of subjecting an acrylic fiber bundle to a heat treatment within a range of 200° C. to 300° C. in an oxidizing atmosphere; a pre-carbonization process of performing a heat treatment within a range of 300° C. to 1,000° C. using a heat treatment furnace having at least one inert gas supply port on each of an incoming side and an outgoing side of the fiber bundle and at least one exhaust port between the incoming-side and outgoing-side inert gas supply ports, the heat treatment being performed with a temperature of an inert gas supplied being higher on the outgoing side than on the incoming side; and a carbonization process of performing a heat treatment at a temperature of 1,000° C. to 2,000° C. in an inert gas atmosphere, in which from a position at which an atmospheric temperature in the heat treatment furnace is 300° C.

Abstract: A method of producing an oxidized fiber bundle includes heat-treating an acrylic fiber bundle aligned in a heat treatment chamber in which hot air is circulated while causing the acrylic fiber bundle to run on direction-changing rollers disposed on both ends of an outside of the heat treatment chamber, wherein first hot air is supplied in a direction substantially parallel to a running direction of the acrylic fiber bundle, and second hot air is supplied from above the acrylic fiber bundle at an angle of 20 to 160° with respect to a wind direction of the first hot air, so that the second hot air passes at least a part of a running acrylic fiber bundle in a longitudinal direction.

Abstract: A method of manufacturing a stabilized fiber bundle is described, which includes subjecting an acrylic fiber bundle aligned, to a heat treatment in an oxidizing atmosphere, with the acrylic fiber bundle being turned around by a guide roller placed on each of both ends outside a hot air heating-type oxidation oven, wherein an air velocity Vm of first hot air sent through a supply nozzle(s) disposed above and/or under a fiber bundle travelled in the oxidation oven, in a substantially horizontal direction to a travelling direction of the fiber bundle, and an air velocity Vf of second hot air flowing in a fiber bundle passing a flow channel in which the fiber bundle is travelled that satisfies expression 1) 0.2?Vf/Vm?2.0??1) to produce a high-quality stabilized fiber bundle and a high-quality carbon fiber bundle at high efficiencies without any process troubles.

Abstract: A method for manufacturing a carbon fiber bundle includes a stabilization process of subjecting an acrylic fiber bundle to a heat treatment within a range of 200° C. to 300° C. in an oxidizing atmosphere; a pre-carbonization process of performing a heat treatment within a range of 300° C. to 1,000° C. using a heat treatment furnace having at least one inert gas supply port on each of an incoming side and an outgoing side of the fiber bundle and at least one exhaust port between the incoming-side and outgoing-side inert gas supply ports, the heat treatment being performed with a temperature of an inert gas supplied being higher on the outgoing side than on the incoming side; and a carbonization process of performing a heat treatment at a temperature of 1,000° C. to 2,000° C. in an inert gas atmosphere, in which from a position at which an atmospheric temperature in the heat treatment furnace is 300° C.

Abstract: A method of producing an oxidized fiber bundle includes heat-treating an acrylic fiber bundle aligned in a heat treatment chamber in which hot air is circulated while causing the acrylic fiber bundle to run on direction-changing rollers disposed on both ends of an outside of the heat treatment chamber, wherein first hot air is supplied in a direction substantially parallel to a running direction of the acrylic fiber bundle, and second hot air is supplied from above the acrylic fiber bundle at an angle of 20 to 160° with respect to a wind direction of the first hot air, so that the second hot air passes at least a part of a running acrylic fiber bundle in a longitudinal direction.

Abstract: A method of manufacturing a stabilized fiber bundle, including travelling an acrylic fiber bundle in an oxidation oven, with the acrylic fiber bundle being conveyed by guide rollers placed on both sides outside the oxidation oven, to subject the acrylic fiber bundle to a heat treatment in an oxidizing atmosphere, wherein a direction of hot air in the oxidation oven is horizontal to a travelling direction of the fiber bundle, and a contact probability P between adjacent fiber bundles, defined by expression (1), is 2 to 18%: P=[1?p(x){?t<x<t}]×100??(1) wherein P represents the contact probability (%) between adjacent fiber bundles, t represents an interspace (mm) between adjacent fiber bundles, p(x) represents a probability density function of a normal distribution N(0, ?2), ? represents a standard deviation of an amplitude of vibration, and x represents a random variable under the assumption that a median amplitude of vibration is zero.

Abstract: A method of manufacturing a stabilized fiber bundle is described, which includes subjecting an acrylic fiber bundle aligned, to a heat treatment in an oxidizing atmosphere, with the acrylic fiber bundle being turned around by a guide roller placed on each of both ends outside a hot air heating-type oxidation oven, wherein an air velocity Vm of first hot air sent through a supply nozzle(s) disposed above and/or under a fiber bundle travelled in the oxidation oven, in a substantially horizontal direction to a travelling direction of the fiber bundle, and an air velocity Vf of second hot air flowing in a fiber bundle passing a flow channel in which the fiber bundle is travelled that satisfies expression 1) 0.2?Vf/Vm?2.0 ??1) to produce a high-quality stabilized fiber bundle and a high-quality carbon fiber bundle at high efficiencies without any process troubles.

Abstract: A method of cleaning an oxidation oven that subjects a polyacrylonitrile-based precursor fiber for carbon fiber to an oxidation treatment in an oxidizing atmosphere, wherein the oxidation oven has a mechanism for circulating an oxidizing gas internally, the method including the steps of: causing a liquid to come in contact with dust adhering to a wall surface of the oxidation oven so that pressure in a direction perpendicular to the wall surface is 2 MPa or more; discharging the liquid out of the oxidation oven to discharge dust peeled off from the wall surface out of the oxidation oven; and circulating an oxidizing gas having a temperature of 40° C. or higher in the oxidation oven.

Abstract: A method of cleaning an oxidation oven that subjects a polyacrylonitrile-based precursor fiber for carbon fiber to an oxidation treatment in an oxidizing atmosphere, wherein the oxidation oven has a mechanism for circulating an oxidizing gas internally, the method including the steps of: causing a liquid to come in contact with dust adhering to a wall surface of the oxidation oven so that pressure in a direction perpendicular to the wall surface is 2 MPa or more; discharging the liquid out of the oxidation oven to discharge dust peeled off from the wall surface out of the oxidation oven; and circulating an oxidizing gas having a temperature of 40° C. or higher in the oxidation oven.