Clamp system equipped with function for detecting behavior of object to be clamped

A clamp system equipped with function for detecting behavior of an object to be clamped, said clamp system being provided in a machining center for processing a clamped object clamped on a reference member through an output member, comprising:

• a clamp device in which an overlapping distance between a coil and the output member made of a magnetic material is changed by stroke movement of the output member;
• a converter for outputting a measured value of an inductance of the coil;
• a memory in which data indicating the measured value of the inductance of the coil when the object to be clamped is clamped on the output member in a process of moving the output member from an unclamped state to a clamped state with respect to the clamped object placed on the reference member as the object to be processed is set as a position of the output member and a clamp area indicating a variation range allowed for the position the output member is set;
• and
• a control unit for reporting an execution of clamping to the machining center after setting the positions of the clamp area and the output member in the memory, measuring the inductance of the coil during processing of the clamped object by the machining center, determining whether the output member it is within a range of the clamp area stored in the memory, and issuing an abnormality to the machining center when the range is exceeded.