Method for machining center holes of forged rotary body and system for machining center holes of forged rotary body

A method for machining center holes in a forged rotary body produced using a forging die assembly, comprising:

• a lot setup step of setting up, as a same one of a sequence of forging lots, a plurality of the forged rotary bodies which are forged within a time period after a die misalignment adjustment for the forging die assembly through before a next die misalignment adjustment for the forging die assembly;
• a three-dimensional shape measurement step of extracting, as samples, two or more of the forged rotary bodies from each of the forging lots, and measuring a three-dimensional shape of each of the samples to acquire measured three-dimensional shape data which is a result of the measurement;
• a temporary-center-hole position setting step of, based on the measured three-dimensional shape data, setting positions of temporary center holes for each of the samples;
• an imbalance amount calculation step of, based on the measured three-dimensional shape data about each of the samples and design three-dimensional shape data about a pre-set design final shape of the forged rotary body, calculating a rotational imbalance amount in a final shape of each of the samples after being subjected to simulation of given machining on the basis of the temporary center holes;
• a determination step of determining whether or not the rotational imbalance amount in each of the samples falls within a pre-set allowable range;
• an average value calculation step of, for any one of the forging lots in which the rotational imbalance amounts in all of the samples are determined to be within the allowable range, calculating an average value of the rotational imbalance amounts in all of the samples of the forging lot;
• a center hole machining position setting step of calculating center-hole positions which allow the average value of the rotational imbalance amounts to become zero, and setting the calculated center-hole positions as center hole machining positions for all of the forged rotary bodies included in the forging lot to which the samples used in the calculation belong;
• and
• a center hole machining step of, during machining of a certain forged rotary body, machining center holes in the certain forged rotary body at the center hole machining positions set for one of the forging lot to which the certain forged rotary body belongs.