Method for processing workpiece in tool machine and behavior measurement device

A method for processing a workpiece in a tool machine for processing said workpiece by relatively moving a tool with respect to said workpiece, said method for processing said workpiece characterized of comprising the following steps:

• a first step for continuously measuring a position of a tip point of a tool attached to an main axis;
• a second step for computing a displacement amount of said position of said tip point of said tool based on a result of a measurement in order;
• a third step for observing whether said displacement amount of said position of said tip point of said tool is within a range of an allowable accuracy previously determined for a certain time period in order to judge whether said position of said tip portion of said tool thermally displaced is converged or not;
• a fourth step for keeping an idling operation in the case that a time period that said displacement amount is within said range of said allowable accuracy is shorter than said certain time period previously determined so as to judge whether said position of said tip portion of said tool thermally displaced is converged or not and intermitting said idling operation in the case that said period that said displacement amount is within said range of said allowable accuracy is equal or longer than said certain time period previously determined;
• and
• a fifth step for starting on processing said workpiece in the case that said idling operation is intermitted in said fourth step.