Turning – Process of turning
Reexamination Certificate
2000-01-28
2001-12-04
Tasi, Henry (Department: 3722)
Turning
Process of turning
C082S001300, C082S118000, C082S129000
Reexamination Certificate
active
06324949
ABSTRACT:
The present disclosure relates to the subject matter disclosed in German Application No. 199 04 253.5 of Application No. 09/493,890 Feb. 3, 1999, the entire specification of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
The invention relates to a machine tool comprising a machine frame, at least one workpiece spindle, in which a workpiece can be clamped and driven for rotation about a workpiece spindle axis, a support, on which the workpiece spindle is arranged and with which the workpiece spindle can be moved relative to the machine frame and transversely to the workpiece spindle axis into at least two spindle stations stationarily defined with respect to the machine frame, and at least one tool carrier associated with a selected one of the spindle stations, comprising a cross-slide carrier (also referred to herein as a “transverse-slide carrier”) mounted on the machine frame and having a cross slide (also referred to herein as a “transversed slide”) for a tool movable in an X direction relative to the workpiece spindle located in the selected spindle station.
A machine tool of this type is known, for example, from DE-A-196 49 016.
In a machine tool of this type, the tool carriers are designed such that they are movable in the direction of an X-axis stationarily defined with respect to the machine frame and, where applicable, of a Z-axis.
As a result, the tool carriers are merely suitable for the use of stationary tools for classic rotary machining or also for the use of rotatingly driven tools, with which, however, only a center machining of the workpieces is possible.
DE-B-33 28 327 discloses, in addition, a possibility, with which an off-center machining of a workpiece is also possible by means of a turret movable in an X-axis.
SUMMARY OF THE INVENTION
Proceeding on the basis of DE 196 49 016, the object underlying the invention is to improve a machine tool of the generic type in such a manner that with a construction which is space-saving in the area of the cross slide a center and off-center machining of the workpiece is possible by means of a rotating tool.
This object is accomplished in accordance with the invention, in a machine tool of the type described at the outset, in that the workpiece held in the workpiece spindle is rotatable about the workpiece spindle axis into defined rotary positions by means of a numerically controlled C-axis, that the cross-slide carrier is pivotable in relation to the machine frame about a pivot axis parallel to the workpiece spindle axis of the workpiece spindle located in the selected spindle station by means of a pivot drive in a numerically controlled manner, that a tool spindle is provided on the cross slide for receiving a tool drivable for rotation about a tool spindle axis and that the tool spindle axis forms with the X direction an angle of less than 45°.
It is possible with the inventive solution to carry out center and off-center machinings of the workpiece with an extremely space-saving mode of construction in the area of the cross slide and without an additional linear axis extending at right angles to the X direction for moving the tool.
In this respect, an off-center machining of the workpiece is understood in the inventive sense as any machining, with which the tool spindle axis does not intersect the workpiece spindle axis but extends at a distance from it.
Furthermore, the X direction is designated in the sense of the present invention as any direction which extends parallel to a direction extending transversely to the pivot axis and preferably in the direction of the workpiece spindle in the selected spindle station.
In principle, the machine control of the inventive solution could coordinate the pivoting of the cross-slide carrier and the pivoting of the workpiece in any optional manner, wherein the only limiting condition is that the tool must be aligned relative to the workpiece such that cutting edges of the tool move on a flight path suitable for chip removal during the relative movement between workpiece and tool.
It is particularly advantageous when the tool spindle axis extends in all the positions of the cross slide in a plane extending at right angles to the workpiece spindle axis of the workpiece spindle located in the selected spindle station.
Since rotating tools for machine tools are preferably designed such that their cutting edges provide an optimum cutting result during movement relative to the workpiece at right angles to the tool spindle axis or in the direction of the tool spindle axis, it is preferably provided for a machine control to be provided, with which in a Y-axis simulation mode the workpiece is movable about the workpiece spindle axis and the cross slide carrier is movable about the pivot axis simultaneously in such a manner that in all the off-center positions of the tool spindle axis provided for the off-center machining of the workpiece by the driven tool the tool spindle axis always extends at right angles to a virtual Y-axis arranged so as to be stationary relative to the workpiece and located in a virtual plane extending through the workpiece spindle axis.
With such a Y-axis simulation mode of the machine control, a movement of the rotating tool relative to the workpiece may be advantageously generated which corresponds to the movements which can be achieved with a conventional Y-axis movement of the tool relative to the workpiece, wherein the simulated, virtual Y-axis is located in the virtual plane and extends radially to the workpiece spindle axis.
In order to be able to machine exact plane surfaces which extend, in particular, parallel to the workpiece spindle axis it is provided for the tool spindle axis to always be at right angles to the virtual plane.
A particularly favorable design of this solution provides for the machine control, in the Y-axis simulation mode, to control the X-axis in addition to the C-axis and to the pivot axis in such a manner that a surface area defined by the entirety of all the rotatingly moved cutting edges of the rotatingly driven tool always moves in a constant alignment to a constant distance from the virtual plane in all the off-center positions of the tool spindle axis. This variation of the Y-axis simulation mode has the great advantage that with it plane surfaces can be generated on the workpiece which extend transversely to the X-axis without a linear axis for the movement of the rotating tool in Y direction being necessary.
One alternative variation provides for the machine control, in the Y-axis simulation mode and in a specific off-center position of the tool spindle axis, to maintain the Y value of the simulated Y-axis determining this position and while this position is being maintained to move the tool linearly at right angles to the virtual plane by controlling the X-axis and, where applicable, the C-axis and the pivot axis. With this variation of the inventive Y-axis simulation mode, a bore may, in particular, be introduced into a workpiece or notches inserted in the known manner off-center.
With respect to the arrangement of the tool spindle axis relative to the X-axis, it has merely be ascertained so far that these form with one another an angle of less than 45°, wherein the angle is preferably intended to be as small as possible.
It has proven to be particularly favorable when the tool spindle axis extends parallel to the X-axis so that particularly during the off-center machining, during which a movement of the rotating tool is intended to take place in the direction of the tool spindle axis, this movement can be controlled in a simple manner in that no rotations about the C-axis and the pivot axis are required when a movement takes place along the X-axis since only a movement of the cross slide in the direction of the X-axis is necessary for the movement of the tool spindle axis parallel to its axial direction.
With respect to the mounting of the cross-slide carrier on the machine frame, the most varied of solutions are conceivable. For example, it would be conceivable to position the cross-slide carrie
Link Helmut Friedrich
Trautmann Guenther Heinrich
Index-Werke GmbH & Co. & KG Hahn & Tessky
Lipsitz Barry R.
Tasi Henry
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