Production method and production device of long fiber reinforced plastic strand

A long fiber reinforced plastic strand production method comprising:

• an impregnation step of continuously introducing a reinforcing fiber bundle into an impregnation head and impregnating a molten thermoplastic into the reinforcing fiber bundle inside the impregnation head;
• a hauling-off step of forming a long fiber reinforced plastic strand by twisting the reinforcing fiber bundle, which has been impregnated with the plastic, in a manner that the reinforcing fiber bundle is rotated at a predetermined number of rotation about its axis while the reinforcing fiber bundle, which has been impregnated with the plastic, is drawn out from the impregnation head, and hauling-off the formed long fiber reinforced plastic strand;
• and
• a winding-up step of guiding the long fiber reinforced plastic strand, which has been hauled off in the hauling-off step, to a winding-up bobbin while rotating the long fiber reinforced plastic strand about the axis of the long fiber reinforced plastic strand in the same rotation direction as that of the reinforcing fiber bundle in the hauling-off step after the hauling-off step, and winding up the rotated long fiber reinforced plastic strand on the winding-up bobbin,
• wherein in the winding-up step, the long fiber reinforced plastic strand is rotated at the number of rotation smaller than that of the reinforcing fiber bundle in the hauling-off step so that a torsional elastic deformation, which has been generated in the long fiber reinforced plastic strand in the hauling-off step, is reduced.