Patent ID: 9381608
Filing Date: 2016-07-05
CPC Classification: B23Q,G05B

Claim Text:
1. A method for improving a finishing accuracy of surfaces of a workpiece processed using a machine tool that includes a rotary shaft that rotates, the method comprising: starting machine processing of a surface of the workpiece; a first step of detecting a time-domain vibration of the rotary shaft and a rotation speed of the rotary shaft during rotation; a second step of calculating a chatter frequency F a third step of calculating a first frequency range and a second frequency range, the first frequency range being calculated by calculating a rotational frequency FCS using formula (6), adding and subtracting an offset value OFS to and from a value obtained by multiplying the rotational frequency FCS by an integer value of N, and defining the resulting values as an upper limit and a lower limit of the first frequency range, and the second frequency range being calculated by calculating a flute passage frequency FCF using formula (7), adding and subtracting an offset value OFF to and from a value obtained by multiplying the flute passage frequency FCF by the integer value of N, and defining the resulting values as an upper limit and a lower limit of the second frequency range; a fourth step of determining whether the chatter frequency falls within one of the first frequency range and the second frequency range, determining that the chatter vibration is a regenerative chatter vibration if the chatter vibration does not fall within either of the frequency ranges and displaying to an operator that the determined type of chatter vibration is a regenerative chatter vibration; a fifth step of, if the chatter frequency falls within one of the first frequency range and the second frequency range, specifying which of the first frequency range and the second frequency range the chatter frequency falls within, determining that the chatter vibration is a flute-passage-period forced chatter vibration if the chatter frequency falls within the second frequency range and displaying to the operator that the determined type of chatter vibration is a flute-passage-period forced chatter vibration; a sixth step of, if the chatter frequency falls within the first frequency range, calculating a determination validity C for a rotational-period forced chatter vibration, determining based on the calculated determination validity C whether the chatter vibration is one of a rotational-period forced chatter vibration and the regenerative chatter vibration, and displaying to the operator that the determined type of chatter vibration is one of the rotational-period forced chatter vibration and the regenerative chatter vibration; and changing operating parameters of the machine tool based on the determined type of generated vibration displayed to the operator to suppress the determined type of generated vibration and minimize a reduction of finishing accuracy on the surface being processed by the machine tool, wherein where: wherein the third step further includes calculating the offset value OFS using formula (8) and calculating the offset value OFF using formula (9), wherein where wherein the sixth step further includes calculating generation frequencies F wherein where: