SPINDLE UNIT OF MACHINE TOOL

摘要

A spindle device of machine tool includes a pressure sensor (31) that detects a pressing force to a rod (18) by a drive (25), a displacement sensor (32) that detects displacement of the rod (18), a tool clamping-force detector (33) that detects a clamping force to a tool (19) by a collet (20) based on the pressing force to the rod (18) and the displacement of the rod (18), and a spring-replacement-timing determining unit (36) that determines a replacement timing of disc springs (24) based on the tool clamping force and a preset biasing force characteristic value of the disc springs (24), thereby allowing highly accurate determination of a replacement timing of a biasing unit by appropriately detecting a tool clamping force.