Method of producing resin-impregnated fiber bundle roll body

A method of producing a resin-impregnated fiber bundle roll body, comprising:

• an unwinding step that takes off a fiber bundle from a bobbin;
• a winding step that rolls up the fiber bundle on a winding core rotating around a fixed axis through a movable winding head to prepare a product;
• and
• a leading step that leads the fiber bundle taken off in the unwinding step to the winding step between the unwinding step and the winding step, wherein
• the leading step or the winding step includes a resin adhesion operation to impregnate the fiber bundle with a resin,
• the winding step includes a fiber content calculation operation to calculate a fiber content Vf [%] in a layer of the resin-impregnated fiber bundle being rolled up on the winding core of an intermediate product to control any one of (i) to (iv) according to the fiber content Vf [%]:
• (i) a resin adhesion amount in the resin adhesion operation;
• (ii) a winding tension of the fiber bundle applied to the intermediate product;
• (iii) a removal amount of a surplus resin layer generated on an outer surface of the intermediate product;
• and
• (iv) a resin viscosity in the intermediate product,
• the winding step further includes a resin-impregnated fiber bundle layer thickness calculation operation to calculate a thickness tFRP of the layer of the resin-impregnated fiber bundle and then the fiber content calculation operation is performed by using the thickness tFRP,
• the winding step further includes an outer diameter measurement operation to measure an outer diameter of the winding core or the intermediate product, and
• the thickness tFRP of the layer of the resin-impregnated fiber bundle, formed between a first time t1 and a second time t2 later than first time t1, is calculated by using:
• a first outer diameter d1 of the winding core or the intermediate product at the first time t1, and a second outer diameter d2 of the winding core or the intermediate product at the second time t2, the first and second outer diameters d1 and d2 being measured by the outer diameter measurement operation.