Machine tool and method for operating the machine tool

Abstract

The invention relates to a machine tool (1) comprising: a machine frame (2); at least one first working spindle (3); at least one second working spindle (4); and a workpiece clamping device (15) having a first workpiece table (16) and a second workpiece table (19). The workpiece clamping device (15) is designed in such a way that - the first workpiece (18) and the second workpiece (21) can be milled in a milling operating mode, and - the first workpiece (18) and the second workpiece (21) can be turned in a turning operating mode.

Description

[0001] MACHINE TOOL AND A METHOD FOR OPERATING THE MACHINE TOOL

[0002] The invention relates to a machine tool and a method for operating the machine tool.

[0003] So-called double-spindle machines are known from WO 2005 / 025801 A1 and WO 00 / 37213 A2. In such double-spindle machines, two workpieces can be machined simultaneously using a tool inserted into each of the tool spindles. Both tool spindles, and thus both tools, are moved synchronously in the three axes of the coordinate system, so that identical machining operations are performed on both workpieces.

[0004] The double-spindle machines known from WO 2005 / 025801 A1 and WO 00 / 37213 A2 have the disadvantage that the machinability of workpieces is limited.

[0005] The object of the present invention was to overcome the disadvantages of the prior art and to provide an improved machine tool and an improved method for operating the machine tool, which would also allow complex workpieces to be machined. At the same time, the machine tool should be highly efficient.

[0006] According to the invention, a machine tool is designed. The machine tool comprises: a machine frame; at least one first work spindle, which is mounted rotatably about a first spindle axis; a workpiece clamping device, which comprises a first workpiece table rotatable about a first workpiece table rotation axis for receiving a first workpiece. The workpiece clamping device is designed such that

[0007] - in a milling operating mode, a first milling tool can be accommodated in the first work spindle, which can rotate about the first spindle axis and can perform a milling operation on the first workpiece and

[0008] - in a turning operation mode, the first workpiece can be rotatably received in the first workpiece table and a first turning tool can be received in the first work spindle, which first turning tool can be held stationary in the first work spindle and a turning operation can be carried out on the first workpiece.

[0009] This has the advantage that the possibility of machining the workpiece in a milling mode and in a turning mode means that the complexity of the workpieces can be increased or the quality of machining of the workpieces can be increased and at the same time a high degree of utilization of the machine tool can be achieved or a high efficiency of the machine tool can be achieved.

[0010] If the workpiece is rotatably mounted in the workpiece table, this means that the workpiece is firmly clamped in the workpiece table and the workpiece table together with the workpiece is rotated around the workpiece table rotation axis.

[0011] Furthermore, it can be provided that the machine tool comprises at least one second work spindle, which is mounted rotatably about a second spindle axis. Furthermore, it can be provided that the workpiece clamping device comprises a second workpiece table rotatable about a second workpiece table rotation axis for receiving a second workpiece. The workpiece clamping device can be designed such that

[0012] - in a milling operating mode, a first milling tool can be accommodated in the first work spindle, which can rotate about the first spindle axis and can carry out a milling operation on the first workpiece, and a second milling tool can be accommodated in the second work spindle, which can rotate about the second spindle axis and can carry out a milling operation on the second workpiece, and

[0013] - in a turning mode, the first workpiece can be rotatably mounted in the first workpiece table, and a first turning tool can be mounted in the first work spindle, which can be held stationary in the first work spindle, and a turning operation can be carried out on the first workpiece, and the second workpiece can be rotatably mounted in the second workpiece table, and a second turning tool can be mounted in the second work spindle, which can be held stationary in the second work spindle, and a turning operation can be carried out on the second workpiece. This has the advantage that the ability to machine two workpieces in a milling mode and a turning mode means that the complexity of the workpieces can be increased, or the quality of the machining of the workpieces can be improved, and at the same time the utilization rate of the machine tool can be increased even further.the efficiency of the machine tool can be further improved.

[0014] In particular, it can be provided that the first work spindle is assigned to the first workpiece table and the second work spindle is assigned to the second workpiece table.

[0015] Furthermore, it can be provided that an automated tool changer is designed, which serves to change or store the different milling tools and turning tools.

[0016] Furthermore, it can be expedient if the first workpiece table and the second workpiece table are arranged on a common swivel bridge, wherein the first workpiece table and the second workpiece table are rotatable about their respective workpiece table rotation axes and wherein the common swivel bridge is pivotable about a swivel bridge axis. This has the advantage that, despite the possibility of machining complex workpieces, the machine tool itself can be kept as simple as possible. Particularly in combination with the possibility of turning and milling, workpieces can thus be machined efficiently and in a variety of ways. Surprisingly, even if the first workpiece table and the second workpiece table are arranged on the common swivel bridge, it is possible to rotate the first workpiece table and the second workpiece table in turning mode and serve as a type of chuck.

[0017] In particular, in such an embodiment, it can be provided that, in the turning mode, the first turning tool is aligned tangentially to the pivot bridge axis, and the second turning tool is also aligned tangentially to the pivot bridge axis. Furthermore, it can be provided that the first turning tool and the second turning tool are aligned tangentially to the pivot bridge axis from the same side.

[0018] Alternatively, the first workpiece table can be arranged on a first pivoting bridge, which is pivotable about a first pivoting bridge axis, and the second workpiece table can be arranged on a second pivoting bridge, which is pivotable about a second pivoting bridge axis, wherein the first pivoting bridge axis and the second pivoting bridge axis are aligned parallel to each other. This offers the advantage of increased flexibility of the machine tool, since the workpiece tables can thus be pivoted independently of one another about the pivoting bridge axis.

[0019] Furthermore, the pivoting bridge axis can be arranged parallel to a horizontal X-axis. This has the advantage of simplifying workpiece machining.

[0020] Another advantageous embodiment is one in which the first workpiece table rotation axis intersects the pivoting bridge axis and is arranged at a right angle to the pivoting bridge axis. This has the advantage that this measure allows for precise machining of the workpiece. This is particularly true for turning workpieces.

[0021] Furthermore, it can be provided that the first turning tool has a first cutting edge and a second cutting edge, wherein by repositioning the first turning tool relative to the first workpiece, in particular by rotating the first turning tool by means of the first work spindle about the first spindle axis, either the first cutting edge or the second cutting edge can be brought into engagement with the first workpiece. This has the advantage that multiple uses are possible with just one turning tool, thus increasing the efficiency of the machine tool.

[0022] In particular, it is conceivable that the first cutting edge is arranged on a first indexable insert and the second cutting edge is arranged on a second indexable insert, wherein the first indexable insert and the second indexable insert are arranged at different positions on the turning tool.

[0023] In an alternative embodiment, it can be provided that the first cutting edge is formed directly on the turning tool and the second cutting edge is formed directly on the turning tool, wherein the first cutting edge and the second cutting edge are formed at different positions on the turning tool. Furthermore, it can be provided that the first cutting edge and the second cutting edge have different cutting edge geometries. This has the advantage that the first cutting edge and the second cutting edge can be used for different turning processes. For example, the first cutting edge can be used for roughing and the second cutting edge for finishing.

[0024] Furthermore, it can be provided that the first cutting edge and the second cutting edge are distributed in the circumferential direction and arranged at the same distance from the first spindle axis on the first turning tool.

[0025] Furthermore, it can be provided that a first positive-locking anti-rotation device is formed between the first work spindle and a first spindle mount or between the first turning tool and the first spindle mount. This has the advantage that, thanks to this measure, the torques introduced by the cutting forces in the turning tool can be transferred to the first spindle mount and thus do not have to be absorbed by the drive motor of the first work spindle.

[0026] In a first embodiment variant, it can be provided that the first positive-locking anti-rotation device is realized in that a shaped projection is formed on the first turning tool, which can be introduced into a shaped recess of the first spindle holder.

[0027] In a second embodiment, it can be provided that the first positive-locking anti-rotation device is realized in that a shaped projection is formed on the first work spindle, which can be introduced into a shaped recess of the first spindle holder.

[0028] In particular, in the first and the second embodiment variant, it can be provided that the shaped projection is designed in the form of a pin directed in the axial direction towards the first spindle receptacle and the shaped recess of the first spindle receptacle has a corresponding counter-contour, such as a bore.

[0029] In particular, in the first and second embodiments, it can be provided that the shaped projection is designed in the form of a toothing directed in the axial direction toward the first spindle receptacle, and the shaped recess of the first spindle receptacle has a corresponding counter-contour, such as a counter-toothing. In a third embodiment, it can be provided that the first positive-locking anti-rotation device is realized by a displaceable element, such as a bolt, being formed in the first spindle receptacle, which can be brought into engagement with a corresponding counter-contour of the first work spindle or the first turning tool.

[0030] According to a further development, it is possible for the workpiece clamping device to have a first receiving table with a first rotary drive, wherein the first workpiece table is coupled to the first receiving table by means of a first quick-change holder, and for the workpiece clamping device to have a second receiving table with a second rotary drive, wherein the second workpiece table is coupled to the second receiving table by means of a second quick-change holder. This measure makes it possible to clamp a further first workpiece on the further first workpiece table during turning or milling of a first workpiece and to easily swap the workpiece tables for a workpiece change. This measure makes it possible to shorten non-productive times. The efficiency of the machine tool can thus be improved.In particular, by providing separate rotary drives for the first receiving table and the second receiving table, a sufficient power supply for the rotary operating mode can be achieved.

[0031] Furthermore, a first braking device can be provided for securing the first work spindle. Furthermore, it can be expedient for a first braking device to be provided for securing the first work spindle and a second braking device to be provided for securing the second work spindle. This has the advantage that this measure can improve dimensional tolerance during workpiece production. Securing the work spindle is understood, in particular, to mean locking the work spindle against rotational movement.

[0032] Furthermore, it can be provided that the first braking device has a first clamping element for frictionally clamping the first work spindle. Furthermore, it can be provided that the second braking device has a second clamping element for frictionally clamping the second work spindle. This has the advantage that this measure allows the work spindle to be fixed in any desired position. Furthermore, such a clamping element can have a simple structure. For example, it is conceivable for the clamping element to be designed in the form of a friction lining, which is pressed against a corresponding friction surface of the work spindle.

[0033] Furthermore, it can be provided that the first braking device serves to positively lock the rotational movement of the first work spindle. Furthermore, it can be provided that the second braking device serves to positively lock the rotational movement of the second work spindle. In particular, it can be provided that the braking device interacts positively with a tool holder. This has the advantage that this measure can achieve precise positioning of the work spindle and that this measure can allow the work spindle to absorb increased torque. This can improve the accuracy of the machining process.

[0034] According to a particular embodiment, it is possible for the first braking device to have a first actuator, in particular a first hydraulic actuator. Furthermore, it can be provided that the second braking device has a second actuator, in particular a second hydraulic actuator. This has the advantage that this measure allows for simple actuation of the braking device.

[0035] According to an advantageous development, the first work spindle can be designed as a motor spindle and has an interface in accordance with the ISO 121164-3:2008 standard for receiving a tool holder. This offers the advantage that such an interface allows for the most precise possible mounting of tool holders, whereby the mounted tool holders can be designed to accommodate milling tools as well as turning tools. This allows for precise mounting of the turning tool, particularly for turning tools.

[0036] According to an advantageous development, the first work spindle and the second work spindle can each be designed as motor spindles and each have an interface in accordance with the ISO 121164-3:2008 standard for receiving a tool holder. This offers the advantage that such an interface allows for the most precise possible mounting of tool holders, whereby the mounted tool holders can be designed to accommodate milling tools as well as turning tools. This allows for precise mounting of the turning tool, particularly for turning tools.

[0037] The interface for accepting a tool holder according to the ISO 121164-3:2008 standard can also be referred to as HSK-T. HSK-T tool holders can be inserted into such an HSK-T interface. In particular, it can also be provided that HSK-A tool holders can be inserted into such an HSK-T interface.

[0038] A motor spindle is a type of drive for a work spindle in a machine tool in which the work spindle is driven directly and not conventionally via a gear or V-belt. The work spindle can be designed as the rotor of the electric motor.

[0039] In particular, it can be advantageous if the workpiece clamping device comprises a first rear workpiece table and a second rear workpiece table, wherein the first workpiece table and the second workpiece table are arranged on a first side of a swivel drum and the first rear workpiece table and the second rear workpiece table are arranged on a second side of the swivel drum, wherein the swivel drum is pivotally mounted about a swivel drum axis, wherein in a first pivot position of the swivel drum, the first workpiece table is assigned to the first work spindle and the second workpiece table is assigned to the second work spindle and in a second pivot position of the swivel drum, the first rear workpiece table is assigned to the first work spindle and the second rear workpiece table is assigned to the second work spindle. By means of this measure, it can be achieved that during the turning orMilling of a first workpiece means that another first workpiece can already be clamped on the first rear workpiece table, which can reduce the idle times.

[0040] Furthermore, it can be provided that the first spindle axis and the second spindle axis are each aligned parallel to a horizontal Z-axis. This measure allows for easy chip removal during both milling and turning operations, thereby improving machining quality.Furthermore, it can be provided that the first workpiece table and the second workpiece table are arranged on a lower pivoting bridge, wherein the first workpiece table and the second workpiece table are rotatable about their respective workpiece table rotational axis and wherein the lower pivoting bridge is pivotable about a lower pivoting bridge axis and that an upper first workpiece table and an upper second workpiece table are arranged on an upper pivoting bridge, wherein the upper first workpiece table and the upper second workpiece table are rotatable about their respective workpiece table rotational axis and wherein the upper pivoting bridge is pivotable about an upper pivoting bridge axis and wherein the upper pivoting bridge and the lower pivoting bridge are arranged one above the other and wherein an upper first work spindle is formed, which is assigned to the upper first workpiece table and an upper second work spindle is formed, which is assigned to the upper second workpiece table.This has the advantage of further increasing the efficiency of the machine tool. This feature can be particularly advantageous for machining four identical workpieces, such as wheel rim machining.

[0041] In a further development, it can be provided that the first work spindle and the upper first work spindle are arranged on a common first spindle mount, and the second work spindle and the upper second work spindle are arranged on a common second spindle mount. This simplifies the machine tool while increasing efficiency.

[0042] Furthermore, it can be provided that the first workpiece is clamped centrally on the first workpiece table and that the center of mass of the first workpiece table lies on the first workpiece table rotation axis. Furthermore, it can be provided that the second workpiece is clamped centrally on the second workpiece table and that the center of mass of the second workpiece table lies on the second workpiece table rotation axis. This has the advantage, particularly in turning mode, that the workpieces can be machined with high precision and can have a good surface quality. Furthermore, this measure improves smoothness in turning mode.

[0043] The invention also relates to a method for operating a machine tool according to one of the above embodiments, wherein when carrying out the method - in a milling operating mode, a first milling tool is accommodated in the first work spindle, which rotates about the first spindle axis and carries out a milling operation on the first workpiece and

[0044] - in a turning operating mode, the first workpiece is rotatably mounted in the first workpiece table and a first turning tool is mounted in the first work spindle, which is held stationary in the first work spindle and a turning operation is carried out on the first workpiece and.

[0045] Furthermore, it may be provided that

[0046] - in a milling operating mode, a first milling tool is accommodated in the first work spindle, which rotates about the first spindle axis and carries out a milling operation on the first workpiece, and a second milling tool is accommodated in the second work spindle, which rotates about the second spindle axis and carries out a milling operation on the second workpiece, and

[0047] - in a turning operating mode, the first workpiece is rotatably received in the first workpiece table and a first turning tool is received in the first work spindle, which is held stationary in the first work spindle and a turning operation is carried out on the first workpiece and the second workpiece is rotatably received in the second workpiece table and a second turning tool is received in the second work spindle, which is held stationary in the second work spindle and a turning operation is carried out on the second workpiece.

[0048] The method according to the invention has the advantage that, due to the possibility of machining two workpieces in a milling mode and in a turning mode, the complexity of the workpieces can be increased or the quality of machining of the workpieces can be increased and, at the same time, a high degree of utilization of the machine tool can be achieved or a high efficiency of the machine tool can be achieved.

[0049] Also advantageous is a method according to which it can be provided that

[0050] - in a milling operating mode, a first milling tool is accommodated in the first work spindle, which rotates about the first spindle axis and carries out a milling operation on the first workpiece, and a second milling tool is accommodated in the second work spindle, which rotates about the second spindle axis and carries out a milling operation on the second workpiece, and - in a turning operating mode, the first workpiece is rotatably accommodated in the first workpiece table, and a first turning tool is accommodated in the first work spindle, which is held stationary in the first work spindle and a turning operation is carried out on the first workpiece, and the second workpiece is rotatably accommodated in the second workpiece table, and a second turning tool is accommodated in the second work spindle, which is held stationary in the second work spindle and a turning operation is carried out on the second workpiece.This has the advantage of improving chip removal during both external and internal turning, resulting in improved workpiece quality.

[0051] According to a further development, it is possible for external turning and internal turning to take place in the turning mode of a hollow cylindrical workpiece, wherein during external turning the first spindle axis and the second spindle axis are each aligned parallel to a horizontal Z-axis and the first workpiece table rotation axis and the second workpiece table rotation axis are each aligned parallel to a vertical Y-axis and wherein during internal turning the first spindle axis and the second spindle axis are each aligned parallel to the horizontal Z-axis and the first workpiece table rotation axis and the second workpiece table rotation axis are each aligned parallel to the horizontal Z-axis.This measure makes it possible to clamp a second workpiece to the second workpiece table during turning or milling of a first workpiece, and to easily swap the workpiece tables for a workpiece change. This measure can reduce downtime, thus improving the efficiency of the machine tool.

[0052] Furthermore, it can be expedient if the first workpiece is clamped on the first workpiece table and a milling and / or turning operation is carried out, wherein at the same time a further first workpiece is clamped on a further first workpiece table and wherein, when the workpiece table is changed, the first quick-change holder is opened and the first workpiece table is removed from the first receiving table and replaced with the further first workpiece table and then the first quick-change holder is closed and the further first workpiece table is clamped on the first receiving table. This measure can ensure that a further first workpiece can already be clamped on the first rear workpiece table during the turning or milling of a first workpiece, thereby reducing non-productive times.

[0053] Furthermore, it can be provided that the first workpiece is clamped on the first workpiece table and a milling and / or turning operation is performed, with another first workpiece being clamped simultaneously on the first rear workpiece table of a swivel drum, and with the swivel drum being rotated 180° during a subsequent workpiece table change. This offers the advantage of minimizing downtime.

[0054] Furthermore, it can be provided that the first workpiece table is pivoted around the pivoting bridge axis during the turning operation. This has the advantage that, for example, undercuts or other special geometric shapes can be easily created during the turning operation.

[0055] Furthermore, it can be provided that, in the turning mode, the first workpiece is rotatably mounted in the first workpiece table, and the first milling tool is mounted in the first work spindle, which is held stationary in the first work spindle, so that the first milling tool acts as the first turning tool and a turning operation is performed on the first workpiece. In particular, one of the several cutting edges arranged on the milling tool can be brought into engagement with the first workpiece. This has the advantage that, thanks to this measure, there is no need to change from a milling tool to a turning tool.

[0056] Furthermore, it can be provided that different cutting edges arranged on the first milling tool are brought into engagement with the first workpiece during different turning processes. This has the advantage of ensuring even wear of the first milling tool.

[0057] In particular, it can be provided that the cutting edges arranged on the first milling tool are distributed in a regular pattern on the first milling tool. For a better understanding of the invention, it is explained in more detail with reference to the following figures.

[0058] They show in a highly simplified, schematic representation:

[0059] Fig. 1 is a perspective view of a first embodiment of a machine tool in a highly schematic representation;

[0060] Fig. 2 is a perspective view of a second embodiment of the machine tool in a highly schematic representation;

[0061] Fig. 3 shows an embodiment of the work spindles in a schematic cross-sectional view;

[0062] Fig. 4 is a perspective view of a third embodiment of the machine tool in a highly schematic representation;

[0063] Fig. 5 is a front view of a fourth embodiment of the machine tool in a highly schematic representation;

[0064] Fig. 6 is a perspective view of a fifth embodiment of the machine tool in a highly schematic representation;

[0065] Fig. 7 shows a first embodiment of a milling tool with a first cutting edge and a second cutting edge;

[0066] Fig. 8 shows a first embodiment of a positive-locking anti-twist device.

[0067] By way of introduction, it should be noted that in the variously described embodiments, identical parts are provided with identical reference symbols or component designations. The disclosures contained throughout the description can be applied analogously to identical parts with identical reference symbols or component designations. Furthermore, the position information chosen in the description, such as top, bottom, side, etc., refers to the directly described and illustrated figure, and these position information must be applied analogously to the new position in the event of a change in position.

[0068] Fig. 1 shows a schematic representation of a first embodiment of a machine tool 1 for machining workpieces 18, 21. The machine tool 1 has a machine frame 2, which serves as a base for the components attached thereto.

[0069] For the sake of clarity, the machine frame 2 is shown only schematically in Fig. 1. However, it should be noted that the machine frame 2 can be anchored at the installation site. Furthermore, the machine frame 2 naturally serves to accommodate all components of the machine tool 1.

[0070] The machine tool 1 comprises a first work spindle 3 and a second work spindle 4. The first work spindle 3 can be mounted for rotation about a first spindle axis 5. The second work spindle 4 can be mounted for rotation about a second spindle axis 6.

[0071] A coordinate system in the machine tool 1 can be defined such that a Z-axis 7 is defined parallel to the spindle axes 5, 6. The Z-axis 7 can be aligned horizontally. An X-axis 8 can be defined perpendicular to the Z-axis 7 and also aligned horizontally. The X-axis 8 and the Z-axis 7 can thus lie in a horizontal plane. A Y-axis 9 is arranged at right angles to the Z-axis 7 and the X-axis 8 and thus runs vertically in the embodiment shown in Fig. 1.

[0072] The first work spindle 3 and the second work spindle 4 can be moved synchronously with each other. In the present embodiment, it can be provided that the first work spindle 3 is displaceable in the longitudinal direction of the first spindle axis 5 and the second work spindle 4 is displaceable in the longitudinal direction of the second spindle axis 6.

[0073] Furthermore, the first work spindle 3 and the second work spindle 4 can be designed to be displaceable in the direction of the X-axis 8.

[0074] The first work spindle 3 and the second work spindle 4 can be arranged on a common spindle adjustment device and can be moved together relative to the machine frame 2. In an alternative embodiment, it is also conceivable for the first work spindle 3 and the second work spindle 4 to each be arranged on their own spindle adjustment device and thus be individually movable relative to the machine frame 2. Of course, a mixed form of this is also conceivable, for example, for the first work spindle 3 and the second work spindle 4 to be designed to be jointly movable in the direction of the X-axis 8 and individually movable in the direction of the Z-axis 7.

[0075] The first work spindle 3 can be designed to accommodate a first milling tool 10 or a first turning tool 11. In particular, it can be provided that the first work spindle 3 has an interface for receiving a tool holder 12, in which the first milling tool 10 or the first turning tool 11 can be accommodated.

[0076] The second work spindle 4 can be designed to accommodate a second milling tool 13 or a second turning tool 14. In particular, the second work spindle 4 can have an interface for receiving a tool holder 12, in which the second milling tool 13 or the second turning tool 14 can be accommodated.

[0077] Furthermore, the machine tool 1 can comprise a tool changer (not shown), which serves to change or store the different milling tools 10, 13 and turning tools 11, 14.

[0078] In addition, the machine tool 1 comprises a workpiece clamping device 15, which serves to hold the workpieces 18, 21 to be machined.

[0079] The workpiece clamping device 15 comprises a first workpiece table 16, which is rotatable about a first workpiece table rotation axis 17. The first workpiece table 16 serves to hold a first workpiece 18.

[0080] The workpiece clamping device 15 comprises a second workpiece table 19, which is rotatable about a second workpiece table rotation axis 20. The second workpiece table 19 serves to hold a second workpiece 21.

[0081] As further evident from Fig. 1, it can be provided that the first workpiece table 16 and the second workpiece table 19 are arranged on a common pivoting bridge 22. The first workpiece table 16 and the second workpiece table 19 can be attached to the common pivoting bridge 22 so as to be rotatable about their respective workpiece table rotation axes 17, 20. Furthermore, it can be provided that the common pivoting bridge 22 is pivotably mounted on the machine frame 2 by means of a first bearing point 23 and a second bearing point 24 so as to be pivotable about a pivoting bridge axis 25.

[0082] In a first embodiment, it can be provided that the common pivot bridge 22 with the first bearing point 23 and the second bearing point 24 is designed to be displaceable in the direction of the Y-axis 9. In an alternative embodiment, it can be provided that the first work spindle 3 and the second work spindle 4 are designed to be displaceable in the direction of the Y-axis 9.

[0083] Furthermore, it can be provided that a first receiving table 26 is arranged on the common pivoting bridge 22, which first receiving table has a first quick-change holder 28. The first quick-change holder 28 can serve to releasably couple the first workpiece table 16 to the first receiving table 26. Furthermore, it can be provided that the first receiving table 26 is coupled to a first rotary drive 27.

[0084] Furthermore, it can be provided that a second receiving table 29 is arranged on the common pivoting bridge 22, which second receiving table has a second quick-change holder 31. The second quick-change holder 31 can serve to releasably couple the second workpiece table 19 to the second receiving table 29. Furthermore, it can be provided that the second receiving table 29 is coupled to a second rotary drive 30.

[0085] By means of the receiving tables 26, 29, the workpiece tables 16, 19 can be rotatably mounted on the common swivel bridge 22.

[0086] By designing the first receiving table 26, it can be achieved that the first workpiece 18 is clamped on the first workpiece table 16, which is held on the first receiving table 26, and a milling and / or turning operation is carried out on the first workpiece 18. At the same time, a further first workpiece 33 can be clamped on a further first workpiece table 32. When changing the workpiece table, the first quick-change holder 28 can be opened and the first workpiece table 16 can be removed from the first receiving table 26 and replaced with the further first workpiece table 32. Subsequently, the first quick-change holder 28 can be closed and the further first workpiece table 32 can be clamped on the first receiving table 26. A corresponding handling device (not shown) can be designed to handle the first workpiece table 16 and the further first workpiece table 32.In particular, it can be provided that the change of the workpiece tables 16, 32 can be carried out automatically by means of the handling device.

[0087] By designing the second receiving table 29, it can be achieved that the second workpiece 21 is clamped on the second workpiece table 19, which is held on the second receiving table 29, and a milling and / or turning operation is carried out on the second workpiece 21. At the same time, a further second workpiece 35 can be clamped on a further second workpiece table 34. When changing the workpiece table, the second quick-change holder 31 can be opened and the second workpiece table 19 can be removed from the second receiving table 29 and replaced with the further second workpiece table 34. The second quick-change holder 31 can then be closed and the further second workpiece table 34 can be clamped on the second receiving table 29. A corresponding handling device can be designed for handling the second workpiece table 34 and the further second workpiece table 34.In particular, it can be provided that the changing of the workpiece tables 19, 34 can be carried out automatically by means of the handling device.

[0088] In such an embodiment, it can be provided that in the turning mode, external turning and internal turning take place on a hollow cylindrical workpiece 18, 21. During external turning, the first spindle axis 5 and the second spindle axis 6 can each be aligned parallel to the horizontal Z-axis 7, and the first workpiece table rotation axis 17 and the second workpiece table rotation axis 20 can each be aligned parallel to the vertical Y-axis 9. During internal turning, the first spindle axis 5 and the second spindle axis 6 can each be aligned parallel to the horizontal Z-axis 7, and the first workpiece table rotation axis 17 and the second workpiece table rotation axis 20 can each be aligned parallel to the horizontal Z-axis 7.

[0089] Fig. 2 shows a further and possibly independent embodiment of the machine tool 1, wherein the same reference numerals or component designations as in the previous Fig. 1 are used for the same parts. To avoid unnecessary repetition, reference is made to the detailed description in the previous Fig. 1. In the second embodiment of the machine tool 1 according to Fig. 2, the first workpiece table 16 is arranged on a first pivot bridge 36, which can be pivoted about a first pivot bridge axis 37. The second workpiece table 19 is arranged on a second pivot bridge 38, which can be pivoted about a second pivot bridge axis 39.

[0090] In particular, it can be provided that the first pivot bridge axis 37 and the second pivot bridge axis 39 are aligned parallel to one another. Furthermore, it can be provided that the first pivot bridge axis 37 and the second pivot bridge axis 39 are arranged one above the other at a distance from one another in the direction of the Y-axis 9.

[0091] Fig. 3 shows a further and possibly independent embodiment of the machine tool 1, wherein the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 and 2. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 and 2.

[0092] In particular, Fig. 3 shows the first work spindle 3 and the second work spindle 4 in a half-sectional view.

[0093] As can be seen from Fig. 3, it can be provided that a first braking device 40 is designed, which serves to fix the first work spindle 3. In particular, it can be provided that the first braking device 40 has a first clamping element 41 for frictionally clamping the first work spindle 3. Furthermore, it can be provided that the first braking device 40 has a first actuator, in particular a first hydraulic actuator 42, which serves to displace the first clamping element 41. Thus, by means of the first hydraulic actuator 42, the first clamping element 41 can be pressed against the first work spindle 3 in order to be able to brake it or to secure it against undesired twisting. In particular, it can be provided that the first clamping element 41 has a friction surface and that a corresponding counter friction surface is formed on the first work spindle 3.

[0094] Furthermore, it can be provided that a second braking device 43 is designed, which serves to fix the second work spindle 4. In particular, it can be provided that the second braking device 43 has a second clamping element 44 for frictionally clamping the second work spindle 4. Furthermore, it can be provided that the second braking device 43 has a second actuator, in particular a second hydraulic actuator 45, which serves to displace the second clamping element 44. Thus, by means of the hydraulic actuator 42, the second clamping element 44 can be pressed against the second work spindle 4 in order to be able to brake it or to secure it against undesired rotation. In particular, it can be provided that the second clamping element 44 has a friction surface and that a corresponding counter friction surface is formed on the second work spindle 4.

[0095] The characteristics of the first work spindle 3 or the second work spindle 4, as described in Fig. 3, can be applied to all embodiments described in the other figures.

[0096] Fig. 4 shows a further and possibly independent embodiment of the machine tool 1, wherein the same reference numerals or component designations are used for the same parts as in the preceding Figures 1 to 3. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figures 1 to 3.

[0097] As can be seen from Fig. 4, it can be provided that a swivel drum 46 is formed. The swivel drum can be pivotally mounted about a swivel drum axis 47. With respect to a plane in which the swivel drum axis 47 lies, the swivel drum 46 can be divided into a first side 48 and a second side 49. Furthermore, it can be provided that the first workpiece table 16 and the second workpiece table 19 are arranged on the first side 48 of the swivel drum 46. Furthermore, a first rear workpiece table 50 and a second rear workpiece table 51 can be arranged on the second side 49 of the swivel drum 46.

[0098] In a first pivoting position of the pivoting drum 46, the first workpiece table 16 is assigned to the first work spindle 3 and the second workpiece table 19 is assigned to the second work spindle 4.

[0099] In a second pivoting position of the swivel drum 46, the first rear workpiece table 50 is assigned to the first work spindle 3, and the second rear workpiece table 51 is assigned to the second work spindle 4. When the swivel drum 46 is in the first pivoting position, the workpieces 18, 21 clamped in the first workpiece table 16 and the second workpiece table 19 can be machined in a milling mode or a turning mode. At the same time, additional workpieces can be clamped and prepared for machining in the first rear workpiece table 50 and the second rear workpiece table 51.

[0100] Once machining of the workpieces 18, 21 clamped in the first workpiece table 16 and the second workpiece table 19 is complete, the swivel drum 46 can be swiveled from the first swivel position to the second swivel position. Machining of the additional workpieces clamped in the first rear workpiece table 50 and the second rear workpiece table 51 can then begin immediately. At the same time, the workpieces 18, 21 clamped in the first workpiece table 16 and the second workpiece table 19 can be removed and replaced with new workpieces.

[0101] In particular, it can be provided that the first workpiece table 16 and the second workpiece table 19 are arranged on the first side 48 of the swivel drum 46 on the common swivel bridge 22. The machine tool 1 can have all the features as described in Fig. 1.

[0102] Furthermore, it can be provided that the first rear workpiece table 50 and the second rear workpiece table 51 are arranged on a rear pivot bridge 52 on the second side 49 of the pivot drum 46. The rear pivot bridge 52 can be pivotable about a rear pivot bridge axis 53.

[0103] The first rear workpiece table 50 and the second rear workpiece table 51 or the rear swivel bridge 52 can have all the features and characteristics already described in connection with Fig. 1. For the sake of brevity, a further description of all the details will be omitted.

[0104] Fig. 5 shows a further and possibly independent embodiment of the machine tool 1, wherein again the same reference numerals or component designations are used for the same parts as in the previous Fig. 1 to 4. To avoid unnecessary repetition, reference is made to the detailed description in the previous Fig. 1 to 4. As can be seen from Fig. 5, the spindle axes 5, 6 can be aligned vertically. The Z-axis 7 can therefore also be aligned vertically. The X-axis 8 can be defined as being perpendicular to the Z-axis 7 and aligned horizontally. The Y-axis 9 is arranged at right angles to the Z-axis 7 and the X-axis 8 and thus also runs horizontally in the embodiment according to Fig. 5. The X-axis 8 and the Y-axis 9 can thus lie in a horizontal plane.

[0105] In such an embodiment, it can be provided that in the turning mode, external turning and internal turning take place on a hollow cylindrical workpiece 18, 21. During internal turning, the first spindle axis 5 and the second spindle axis 6 can each be aligned parallel to the vertical Z-axis 7, and the first workpiece table rotation axis 17 and the second workpiece table rotation axis 20 can also each be aligned parallel to the vertical Z-axis 7. During internal turning, the first spindle axis 5 and the second spindle axis 6 can each be aligned parallel to the vertical Z-axis 7, and the first workpiece table rotation axis 17 and the second workpiece table rotation axis 20 can each be aligned parallel to the horizontal Y-axis 9.

[0106] Fig. 6 shows a further and possibly independent embodiment of the machine tool 1, wherein the same reference numerals or component designations are used for the same parts as in the preceding Figures 1 to 5. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figures 1 to 5.

[0107] As can be seen from Fig. 6, the first workpiece table 16 and the second workpiece table 19 can be arranged on a lower pivot bridge 54, wherein the first workpiece table 16 and the second workpiece table 19 are rotatable about their respective workpiece table rotation axes 17, 20. The lower pivot bridge 54 can be pivotable about a lower pivot bridge axis 55.

[0108] Furthermore, an upper first workpiece table 56 and an upper second workpiece table 57 can be arranged on an upper pivoting bridge 58. The upper first workpiece table 56 and the upper second workpiece table 57 can be rotated about their respective workpiece table rotation axes. The upper pivoting bridge 58 can be pivoted about an upper pivoting bridge axis 59. The upper pivoting bridge 58 and the lower pivoting bridge 54 are arranged one above the other. Furthermore, an upper first work spindle 60 can be formed, which is assigned to the upper first workpiece table 56, and an upper second work spindle 61 can be formed, which is assigned to the upper second workpiece table 57.

[0109] The first work spindle 3 and the upper first work spindle 60 can be arranged on a common first spindle mount 62. The second work spindle 4 and the upper second work spindle 61 can be arranged on a common second spindle mount 63.

[0110] In particular, it can be provided that the first spindle mount 62 serves for the joint displacement of the first work spindle 3 and the upper first work spindle 60. Furthermore, it can be provided that the second spindle mount 63 serves for the joint displacement of the second work spindle 4 and the upper second work spindle 61. This allows the overall structure of the machine tool 1 to be kept as simple as possible, and the number of required actuators can also be kept as low as possible.

[0111] The first workpiece table 16 and the second workpiece table 19, as well as the lower pivoting bridge 54, can have all the features and characteristics already described in connection with Fig. 1. A further description of all details is omitted for the sake of brevity.

[0112] The upper first workpiece table 56 and the upper second workpiece table 57 as well as the upper pivoting bridge 58 can have all the features and characteristics already described in connection with Fig. 1. For the sake of brevity, a further description of all the details will be omitted.

[0113] Fig. 7 shows a further and possibly independent embodiment of the machine tool 1, wherein the same reference numerals or component designations as in the previous Figures 1 to 6 are used for the same parts. To avoid unnecessary repetition, reference is made to the detailed description in the previous Figures 1 to 6. In particular, it is pointed out that the detail as shown in Fig. 7 is applicable to all designs or working spindles of the machine tool 1. As can be seen from Fig. 7, it can be provided that the first turning tool 11 has a first cutting edge 64 and a second cutting edge 65. The first cutting edge 64 and a second cutting edge 65 can be formed directly on the turning tool 11 or on indexable inserts.By rotating the first turning tool 11 by means of the first work spindle 3 about the first spindle axis 5, in the turning mode, either the first cutting edge 64 or the second cutting edge 65 can be brought into engagement with the first workpiece 18. Of course, it is also conceivable for the first turning tool 11 to have additional cutting edges.

[0114] Fig. 8 shows a further and possibly independent embodiment of the machine tool 1, wherein the same reference numerals or component designations are used for the same parts as in the preceding Figs. 1 to 7. To avoid unnecessary repetition, reference is made to the detailed description in the preceding Figs. 1 to 7. In particular, it is noted that the detail shown in Fig. 8 is applicable to all designs or working spindles of the machine tool 1.

[0115] As can be seen from Fig. 8, it can be provided that a first positive-locking anti-rotation device 66 is formed between the first work spindle 3 and a first spindle receptacle 62 or between the first turning tool 11 and the first spindle receptacle 62. In the present exemplary embodiment, the positive-locking anti-rotation device 66 can be designed in the form of a torque arm, which connects the first turning tool 11 in a positive-locking manner to the first spindle receptacle 62. Loosening or locking can be achieved, for example, by axially displacing the first work spindle 3 along the first spindle axis.

[0116] The embodiments show possible embodiments, whereby it should be noted at this point that the invention is not limited to the specifically illustrated embodiments thereof, but rather various combinations of the individual embodiments with each other are also possible and this possibility of variation lies in the ability of the person skilled in the art in this technical field due to the honor of technical action through the objective invention.

[0117] The scope of protection is determined by the claims. However, the description and drawings must be used to interpret the claims. Individual features or combinations of features from the various embodiments shown and described may represent independent inventive solutions. The problem underlying these independent inventive solutions can be derived from the description.

[0118] All information on value ranges in this description is to be understood as including any and all sub-ranges thereof, e.g. the information 1 to 10 is to be understood as including all sub-ranges starting from the lower limit of 1 and the upper limit of 10, ie all sub-ranges begin with a lower limit of 1 or greater and end with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1, or 5.5 to 10.

[0119] For the sake of clarity, it should finally be pointed out that, in order to better understand the structure, some elements have been shown out of scale and / or enlarged and / or reduced in size.

[0120] Reference symbol list

[0121] Machine tool 32 additional first workpiece table

[0122] Machine frame 33 further first workpiece first work spindle 34 further second workpiece table second work spindle 35 further second workpiece first spindle axis 36 first swivel bridge second spindle axis 37 first swivel bridge axis

[0123] Z-axis 38 second swing bridge

[0124] X-axis 39 second swing bridge axis

[0125] Y-axis 40 first braking device first milling tool 41 first clamping element first turning tool 42 first hydraulic actuator

[0126] Tool holder 43 second braking device second milling tool 44 second clamping element second turning tool 45 second hydraulic actuator

[0127] Workpiece clamping device 46 Swivel drum first workpiece table 47 Swivel drum axis first workpiece table rotation axis 48 first side first workpiece 49 second side second workpiece table 50 first rear workpiece second workpiece table rotation axis table second workpiece 51 second rear workpiece common swivel bridge table first bearing point 52 rear swivel bridge second bearing point 53 rear swivel bridge

[0128] Swivel bridge axis axis first receiving table 54 lower swivel bridge first rotary drive 55 lower swivel bridge axis first quick-change holder 56 upper first workpiece table second receiving table 57 upper second workpiece table second rotary drive 58 upper swivel bridge second quick-change holder 59 upper swivel bridge axis upper first work spindle upper second work spindle first spindle holder second spindle holder first cutting edge second cutting edge anti-twist device torque support

Claims

Patent claims 1. Machine tool (1) comprising: a machine frame (2); at least one first work spindle (3) which is mounted rotatably about a first spindle axis (5); a workpiece clamping device (15) which comprises a first workpiece table (16) rotatable about a first workpiece table rotation axis (17) for receiving a first workpiece (18), characterized in that the workpiece clamping device (15) is designed such that - in a milling operating mode, a first milling tool (10) can be accommodated in the first work spindle (3), which can rotate about the first spindle axis (5) and can carry out a milling operation on the first workpiece (18), and - in a turning operating mode, the first workpiece (18) can be rotatably received in the first workpiece table (16) and a first turning tool (11) can be received in the first work spindle (3), which first turning tool (11) can be held stationary in the first work spindle (3) and a turning operation can be carried out on the first workpiece (18).

2. Machine tool (1) according to claim 1, further comprising at least one second work spindle (4) which is mounted rotatably about a second spindle axis (6); a second workpiece table (19) rotatable about a second workpiece table rotation axis (20) for receiving a second workpiece (21), wherein the workpiece clamping device (15) is designed such that - in a milling operating mode, a first milling tool (10) can be accommodated in the first work spindle (3), which can rotate about the first spindle axis (5) and can carry out a milling operation on the first workpiece (18), and a second milling tool (13) can be accommodated in the second work spindle (4), which can rotate about the second spindle axis (6) and can carry out a milling operation on the second workpiece (21), and - in a turning operating mode, the first workpiece (18) can be rotatably received in the first workpiece table (16) and a first turning tool (11) can be received in the first work spindle (3), which can be held stationary in the first work spindle (3) and a turning operation can be carried out on the first workpiece (18), and the second workpiece (21) can be rotatably received in the second workpiece table (19) and a second turning tool (14) can be received in the second work spindle (4), which can be held stationary in the second work spindle (4) and a turning operation can be carried out on the second workpiece (21).

3. Machine tool (1) according to claim 2, characterized in that the first workpiece table (16) and the second workpiece table (19) are arranged on a common pivoting bridge (22), wherein the first workpiece table (16) and the second workpiece table (19) are rotatable about their respective workpiece table rotational axis (17, 20) and wherein the common pivoting bridge (22) is pivotable about a pivoting bridge axis (25).

4. Machine tool (1) according to claim 2, characterized in that the first workpiece table (16) is arranged on a first pivoting bridge (36) which is pivotable about a first pivoting bridge axis (37) and the second workpiece table (19) is arranged on a second pivoting bridge (38) which is pivotable about a second pivoting bridge axis (39), wherein the first pivoting bridge axis (37) and the second pivoting bridge axis (39) are aligned parallel to one another.

5. Machine tool (1) according to one of claims 1 to 4, characterized in that the pivoting bridge axis (25, 37, 38) is arranged parallel to a horizontal X-axis (8).

6. Machine tool (1) according to one of claims 2 to 5, characterized in that the first workpiece table rotation axis (17) intersects the pivot bridge axis (25, 37) and is arranged at a right angle to the pivot bridge axis (25, 37).

7. Machine tool (1) according to one of the preceding claims, characterized in that the first turning tool (11) has a first cutting edge (64) and a second cutting edge (65), wherein by repositioning the first turning tool (11) relative to the first workpiece (18), in particular by rotating the first turning tool (11) by means of the first work spindle (3) about the first spindle axis (5), either the first cutting edge (64) or the second cutting edge (65) can be brought into engagement with the first workpiece (18).

8. Machine tool (1) according to claim 7, characterized in that the first cutting edge (64) and the second cutting edge (65) have a different cutting edge geometry.

9. Machine tool (1) according to one of the preceding claims, characterized in that a first positive-locking anti-rotation device (66) is formed between the first work spindle (3) and a first spindle holder (62) or between the first turning tool (11) and the first spindle holder (62).

10. Machine tool (1) according to one of claims 2 to 9, characterized in that the workpiece clamping device (15) has a first receiving table (26) with a first rotary drive (27), wherein the first workpiece table (16) is coupled to the first receiving table (26) by means of a first quick-change holder (28) and that the workpiece clamping device (15) has a second receiving table (29) with a second rotary drive (30), wherein the second workpiece table (19) is coupled to the second receiving table (29) by means of a second quick-change holder (31).

11. Machine tool (1) according to one of the preceding claims, characterized in that a first braking device (40) is formed, which serves to fix the first work spindle (3).

12. Machine tool (1) according to claim 11, characterized in that the first braking device (40) has a first clamping element (41) for frictionally clamping the first work spindle (3).

13. Machine tool (1) according to claim 11, characterized in that the first braking device (40) serves to positively lock the rotational movement of the first work spindle (3), in particular that the braking device (40, 43) each cooperates positively with a tool holder (12).

14. Machine tool (1) according to one of claims 11 to 13, characterized in that the first braking device (40) has a first actuator, in particular a first hydraulic actuator (42).

15. Machine tool (1) according to one of the preceding claims, characterized in that the first work spindle (3) is designed as a motor spindle and has an interface according to the standard ISO 121164-3:2008 for receiving a tool holder (12).

16. Machine tool (1) according to one of claims 2 to 15, characterized in that the workpiece clamping device (15) comprises a first rear workpiece table (50) and a second rear workpiece table (51), wherein the first workpiece table (16) and the second workpiece table (19) are arranged on a first side (48) of a swivel drum (46) and the first rear workpiece table (50) and the second rear workpiece table (51) are arranged on a second side (49) of the swivel drum (46), wherein the swivel drum (46) is pivotally mounted about a swivel drum axis (47), wherein in a first pivot position of the swivel drum (46), the first workpiece table (16) is assigned to the first work spindle (3) and the second workpiece table (19) is assigned to the second work spindle (4), and in a second pivot position of the swivel drum (46),the first rear workpiece table (50) is assigned to the first work spindle (3) and the second rear workpiece table (51) is assigned to the second work spindle (4).

17. Machine tool (1) according to one of claims 2 to 16, characterized in that the first spindle axis (5) and the second spindle axis (6) are each aligned parallel to a horizontal Z-axis (7).

18. Machine tool (1) according to one of claims 2 to 17, characterized in that the first workpiece table (16) and the second workpiece table (19) are arranged on a lower pivoting bridge (54), wherein the first workpiece table (16) and the second workpiece table (19) are rotatable about their respective workpiece table rotational axes (17, 20) and wherein the lower pivoting bridge (54) is pivotable about a lower pivoting bridge axis (55), and that an upper first workpiece table (56) and an upper second workpiece table (57) are arranged on an upper pivoting bridge (58), wherein the upper first workpiece table (56) and the upper second workpiece table (57) are rotatable about their respective workpiece table rotational axes and wherein the upper pivoting bridge (58) is pivotable about an upper pivoting bridge axis (59), and wherein the upper pivoting bridge (58) and the lower pivoting bridge (54) are arranged one above the other, and wherein an upper first work spindle (60) is formed is,which is assigned to the upper first workpiece table (56) and an upper second work spindle (61) is formed, which is assigned to the upper second workpiece table (57).

19. Machine tool (1) according to claim 18, characterized in that the first work spindle (3) and the upper first work spindle (60) are arranged on a common first spindle holder (62) and the second work spindle (4) and the upper second work spindle (61) are arranged on a common second spindle holder (63).

20. Machine tool (1) according to one of the preceding claims, characterized in that the first workpiece (18) is clamped centrally on the first workpiece table (16) and that the center of mass of the first workpiece table (16) lies on the first workpiece table rotation axis (17).

21. Method for operating a machine tool (1) according to one of the preceding claims, characterized in that - in a milling operating mode, a first milling tool (10) is accommodated in the first work spindle (3), which tool rotates about the first spindle axis (5) and carries out a milling operation on the first workpiece (18) carries out and - in a turning operating mode, the first workpiece (18) is rotatably received in the first workpiece table (16) and a first turning tool (11) is received in the first work spindle (3), which first turning tool (11) is held stationary in the first work spindle (3) and a turning operation is carried out on the first workpiece (18).

22. The method according to claim 21, characterized in that in the turning mode of operation, external turning and internal turning are carried out on a hollow cylindrical workpiece (18, 21), wherein during external turning the first spindle axis (5) and the second spindle axis (6) are each aligned parallel to a horizontal Z-axis (7) and the first workpiece table rotation axis (17) and the second workpiece table rotation axis (20) are each aligned parallel to a vertical Y-axis (9) and wherein during internal turning the first spindle axis (5) and the second spindle axis (6) are each aligned parallel to the horizontal Z-axis (7) and the first workpiece table rotation axis (17) and the second workpiece table rotation axis (20) are each aligned parallel to the horizontal Z-axis (7).

23. Method according to claim 21 or 22, characterized in that the first workpiece (18) is clamped on the first workpiece table (16) and a milling operation and / or turning operation is carried out, wherein at the same time a further first workpiece (33) is clamped on a further first workpiece table (32) and wherein, when the workpiece table is changed, the first quick-change holder (28) is opened and the first workpiece table (16) is removed from the first receiving table (26) and replaced with the further first workpiece table (32) and then the first quick-change holder (28) is closed and the further first workpiece table (32) is clamped on the first receiving table (26).

24. Method according to claim 21 or 22, characterized in that the first workpiece (18) is clamped on the first workpiece table (16) and a milling and / or turning operation is carried out, wherein at the same time on the first rear workpiece table (50) a swivel drum (46) a further first workpiece (33) is clamped and wherein during a subsequent workpiece table change the swivel drum (46) is rotated by 180°.

25. Method according to one of claims 21 to 24, characterized in that while the turning operation is carried out, the first workpiece table (16) is pivoted about the pivot bridge axis (25, 37).

26. Method according to one of claims 21 to 25, characterized in that in the turning operating mode, the first workpiece (18) is rotatably received in the first workpiece table (16) and the first milling tool (10) is received in the first work spindle (3), which is held stationary in the first work spindle (3), so that the first milling tool (10) acts as the first turning tool (11) and a turning operation is carried out on the first workpiece (18).

27. Method according to claim 26, characterized in that during different turning operations different cutting edges arranged on the first milling tool 10 are brought into engagement with the first workpiece (18).

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