Friction stir tool control method and friction stir device

A friction stir tool control method for controlling an operation of a friction stir tool by supplying a necessary drive electric current to a drive source of the tool, the friction stir tool control method comprising:

• obtaining a pressurizing force change ratio by comparing a set pressurizing force predefined as a pressurizing force at plunging of the tool into a workpiece supported by a c-frame with an actual pressurizing force occurring at actual plunging of the tool into the workpiece by supplying a drive electric current for generating the set pressurizing force to the drive source;
• obtaining a table showing a relationship between the drive electric current and the pressurizing force;
• obtaining a third drive electric current actually flowing to the drive source which is activated with a second drive electric current to cause the tool to act to the workpiece, the second drive electric current being obtained by regulating, on the basis of the pressurizing force change ratio, a first drive electric current calculated from the set pressurizing force;
• obtaining a fourth drive electric current by inversely regulating the third drive electric current on the basis of the pressurizing force change ratio, and obtaining a calculated pressurizing force converted from the inversely corrected fourth drive electric current with reference to the table;
• and
• regulating the drive electric current instruction value based on the calculated pressurizing force so as to compensate for deflection of the c-frame.