| 摘要 |
A machining unit for an automatic machine-tool comprises a hollow body (10) fixed to the frame of said machine. In its interior there is arranged a spindle (14) housed freely rotatably without axial sliding inside a sleeve (12) sliding axially inside the hollow body (10). The spindle 14 projects from the body (10) at the front end so as to hold a tool (16), while at the rear end it is supported in a rigidly rotatable manner and with the possibility of axial sliding by support means (20) made to rotate by actuating means (28). The axial displacements of the spindle (14) are performed together with those of the sleeve (12), owing to actuating means cooperating therewith. At the rear end of the sleeve (12) there is fixed an annular collar (30), coaxial with said support means (20) and having a greater diameter than the latter. Located axially opposite the collar (30) there is an internal annular shoulder (31) of the sleeve (12), coaxial with the spindle (14) and having a greater diameter than the latter. The collar (30) has at least one radial lug (34,34') sliding in a longitudinal slit (36,36') thereof when the sleeve (12) is displaced axially. At the rear of the collar (30) there is provided an annular cavity (38) communicating with the exterior of the body (10) via two rectlinear ducts (44,44a) for supplying and discharging a fluid under pressure and an additional annular cavity (40), coaxial with the support means (20), which communicates with the exterior of the body (10) via a radial passage (42). <IMAGE>
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