The present disclosure mainly uses a transmitting unit to drive the fiber yarn bunch to pass an operation region of the microwave processing unit, and the microwave is focused to perform an ultra-fast pre-oxidization process on the passed fiber yarn bunch, thus processing the fiber yarn bunch to form an oxidation fiber yarn bunch. Not only an oxidization time of an oxidation fiber can be reduced, but also the cross section area of the oxidation layer of the oxidation fiber in the oxidation fiber yarn bunch generated by the microwave focusing oxidization process occupies more than 50% of the cross section area of the oxidation fiber in the oxidation fiber yarn bunch. Thus, the shell-core structure of the oxidation fiber can be reduced efficiently. Even, the oxidation fiber has no obvious shell-core structure. Accordingly, relatively positive and reliable means for increasing the performance of carbon fiber are provided.

The present disclosure mainly uses a transmitting unit to drive the fiber yarn bunch to pass an operation region of the microwave processing unit, and the microwave is focused to perform an ultra-fast pre-oxidization process on the passed fiber yarn bunch, thus processing the fiber yarn bunch to form an oxidation fiber yarn bunch. Not only an oxidization time of an oxidation fiber can be reduced, but also the cross section area of the oxidation layer of the oxidation fiber in the oxidation fiber yarn bunch generated by the microwave focusing oxidization process occupies more than 50% of the cross section area of the oxidation fiber in the oxidation fiber yarn bunch. Thus, the shell-core structure of the oxidation fiber can be reduced efficiently. Even, the oxidation fiber has no obvious shell-core structure. Accordingly, relatively positive and reliable means for increasing the performance of carbon fiber are provided.

Techniques produce a crimped composite thread, in which multiple individual threads are extruded in each case in the form of a plurality of strand-shaped filaments, cooled, drawn by means of a drawing device and together crimped by means of a crimping device to form the composite thread. Before the multifilament individual threads are crimped, they are entangled separately in each case by means of an entangling unit of an entangling device. A position and/or orientation of at least one of the entangling units relative to the drawing device, the crimping device and/or a further one of the entangling units is changed during the production of the crimped composite thread.