| 摘要 |
An automatic turret for a lathe and the like comprises a fixed base, a control screw mounted to be rotatable and axially non-displaceable, a nut connected to a tool-carrying body, two basic toothed crowns and at least one latch for arresting the tool-carrying body. The turret has a central column supporting a hollow-rotor motor at its upper end and said control screw at the lower end thereof, an epicyclic reduction gear associated with said motor and having an initial end toothed wheel fixed to said column and a second end wheel, rotatable on said column, and connected to said control screw, a positioning device of the tool-carrying body comprising at least one annular guiding recess provided on the inner cylindrical surface of the body itself, co-axial with the axis of the turret and interrupted on its circumference at at least one point by at least one notch or radial tooth, the said annular recess also being provided with at least one tooth or the like projecting radially from the control screw, and at least one pre-loaded spring interposed so as to penetrate within said annular recess between the tooth projecting from the screw and one flank of the notch or radial tooth present in the recess. The tooth of the screw travels an angular path within said recess of the tool-carrying body corresponding to the axial movement for the disengagement of the body from the base in which path the said spring is partially unloaded. After disengagement, the body is rotated directly by the tooth of the screw until reaching the new working position; at least one latch or the like, slides on guides and is adapted to penetrate into recesses formed in the base so as to arrest the tool-carrying body when it has reached the new position, this arrest remaining stable during the reversal of the rotation of the screw adapted to lower the tool-carrying body until the basic toothed crowns are locked and the spring inserted in the guide recess is restressed. The stability of locking of the screw is ensured by an electro-magnetic brake acting directly on the motor. |
