Spindle device for machine tools

摘要

A spindle device for machine tools that can eliminate the need for laborious air bleeding work and labor-demanding fitting/removing work for maintenance. The spindle device for machine tools includes a drawbar (31) that is axially movably inserted into an axial hole (20b) of a tool spindle (20) body. The drawbar (31) serves to bias a tool (T) in a clamping direction. An unclamping cylinder mechanism (35) is provided in a rear of the tool spindle (20) and serves to move the drawbar (31) in an unclamping direction. The unclamping cylinder mechanism (35) has a cylinder block (37) fixed to a rear end wall of the tool spindle body and includes a plurality of bolts. A relay oil passage allows a hydraulic passage in the tool spindle body and a hydraulic passage (42) in the cylinder block (37) to communicate with each other. The relay oil passage is formed in one locking bolt (46) out of the plurality of bolts (45). The unclamping cylinder mechanism is supported by the locking bolt (46) so as to be pivotable between a locked position where the unclamping cylinder mechanism is fixed by the locking bolt (46) and a released position where it allows access to the spindle (20) and the drawbar (31).