Lathe

Details Lathe Lathe

1989-08-22

1991-04-16

Schmidt, Frederick R.

Turning

Lathe

With program control

82121, 82159, B23B 300

Patent

active

050073141

DESCRIPTION:

BRIEF SUMMARY
The invention relates to a lathe comprising a main work spindle drivable by numerical control and a turret with several indexing stations, the turret having at least one drivable tool spindle, being mounted on a turret slide for rotation about a turret axis, and being rotatable by numerical control about the turret axis by a turret driving device for eccentric machining, with respect to the main work spindle axis, of a workpiece held by the main work spindle by means of a driven tool of the turret, and also comprising a switchable device for securing the turret against rotation.
Such a lathe wherein a main work spindle displaceable in the direction of the so-called Y-axis (axis perpendicular to the plane of motion of the turret) is replaced by the main work spindle and the turret being slowly and synchronously rotatable by numerical control, with the axis of that tool spindle of the turret that is employed moving in a plane extending perpendicularly to the axis of the main work spindle, is known from the applicant's German patent 3 328 327. A numerically controlled electric motor carries out both the indexing of the turret to bring another of its indexing stations into the working position and the slow, numerically controlled rotation of the turret synchronously with the rotation of the main work spindle. However, this motor also has to prevent undesired rotation of the turret when a rotating workpiece held by the main work spindle is subjected to a normal turning operation with one of its non-driven tools. Since quite considerable cutting forces can occur during this operation, securing of the turret against rotation by means of the turret driving device alone is unsatisfactory. It has, therefore, been attempted to prevent such undesired rotations of the turret by means of a switchable blocking brake which does, however, have a considerable space requirement.
The object underlying the invention was, therefore, to improve the above-described known lathe such that the turrret is securable against undesired rotation by a switchable locking device of compact and sturdy design for normal turning of a workpiece held by the main work spindle with a tool of the turret, but for operations with rotating main work spindle and rotating turret, the latter is also held exactly in position in the unlocked state.
In a lathe of the kind mentioned at the beginning, this object is accomplished in accordance with the invention in that for positive locking of the turret against rotation, spur gears displaceable relative to one another in the direction of the turret axis are connected to the turret and to the turret slide in a rotationally fixed manner, and in that a bearing is provided for the turret which in the unlocked state of the latter is free from play. The device for securing against rotation comprising the spur gears may be a two-part Curvic coupling, the one spur gear of which is displaceable in the axial direction, or a three-part Curvic coupling with two concentrically arranged, ring-shaped spur gears, with one of these fixedly attached to the turret and the other to the turret slide, and opposite these a third ring-shaped spur gear which is non-rotatably but axially displaceably mounted on the turret or better on the turret slide. Since such spur gears as, for example, a Curvic coupling can be or are designed such that the meshing spur gear rims concentric with the turret axis have a centering effect with respect to the turret axis, the aforementioned turret bearing can be readily ineffective when the turret is locked.
The inventive solution has the advantages that it can be implemented in an extremely small and compact manner and that for normal turning of a workpiece, the turret is held in a rotationally fixed manner by positive connection and centrically so additional movable parts such as a blocking brake or, for example, a locking bolt movable in the radial direction, are not necessary.
The locking of a turret on the turret slide of a lathe with the aid of a two-part Curvic coupling is already known in quite

REFERENCES:
patent: 3798721 (1974-03-01), Schalles
patent: 4468991 (1984-09-01), Bleusch et al.

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