MACHINE TOOL HAVING A GANTRY

Abstract

A machine tool comprises a frame, which carries a fixed gantry for supporting at least one tool spindle. The gantry comprises a gantry recess, through which a working space is accessible. The one or more tool spindles on the gantry can each be moved vertically in a first direction and in a second direction orthogonal to the first direction. The machine tool further comprises a workpiece table with at least one location for supporting workpieces. The workpiece table is movable in translation in a third direction Y orthogonal to the first direction and the second direction. At least one tool magazine is associated with the at least one tool spindle tool spindle. Tools for tool changing can be fed through at least one magazine opening in the gantry. Tool changing between the one or more tool spindles and the at least one tool magazine takes place in a pick-up process.

Claims

1.-30. (canceled)

31. A machine tool having a normal and a crosswise operating mode comprising: a frame; a first tool spindle with a primary working position, the first tool spindle movable in an X and a Z direction; a second tool spindle with a second tool spindle primary working position, the second tool spindle movable in an X and a Z direction; a fixed gantry, which is supported by the frame, that supports the first tool spindle and the second tool spindle; a workpiece table having at least one workpiece support location configured to support workpieces; wherein: in the normal operating mode the first tool spindle is in the primary working position and associated with a first workpiece support location, and the second tool spindle is in the second tool spindle primary working position and associated with a second workpiece support location, in the crosswise operating mode the first tool spindle is in the second tool spindle primary working position and associated with the second table, and the second tool spindle is in one of a tool change area, a parking position or a service position.

32. The machine tool of claim 31, further comprising: a first tool holder associated with the first tool spindle and a second tool holder associated with the second tool spindle.

33. The machine tool of claim 31, wherein the workpiece table is movable in a Y direction.

34. The machine tool of claim 31, wherein: the workpiece table is pivotable about an axis that extends parallel to the X direction, two jointly controlled drives are provided for the movement of the workpiece table in the Y direction, and two jointly controlled swivel drives are provided for a pivoting movement of the workpiece table about the axis that extends parallel to the X direction.

35. The machine tool of claim 31, further comprising, for the workpiece table, a first rotary table, which is associated with the first tool spindle in the normal operating mode, and a second rotary table, which is associated with the second tool spindle in the normal operating mode.

36. The machine tool of claim 31, wherein the first tool spindle and the second tool spindle are synchronously movable together in the X direction.

37. The machine tool of claim 31, wherein the first tool spindle and the second tool spindle are movable in the X direction on the gantry such that when transitioning from the normal operating mode to the crosswise operating mode: the first tool spindle, departing from the primary working position associated with the first workpiece support location, is movable towards the second workpiece support location when the second tool spindle is moved away from the second workpiece support location, and the second tool spindle, departing from the second tool spindle primary working position associated with the second workpiece support location, is movable away from the second tool spindle primary working position when the first tool spindle is moved away from the first workpiece support location.

38. The machine tool of claim 31, wherein the first tool spindle and the second tool spindle are movable independently of one another in the X direction for tool changing.

39. The machine tool of claim 31, wherein the first tool spindle is movable to a first tool change area, and the second tool spindle is movable to a second tool change area.

40. The machine tool of claim 39, wherein the first tool spindle is vertically movable in the first tool change area to change a machining tool, and the second tool spindle is vertically movable in the second tool change area to change a machining tool.

41. The machine tool of claim 31, further comprising on the workpiece table at least one location configured to support at least one pallet.

42. The machine tool of claim 31, further comprising a pallet changer, the pallet changer configured to be coupled to the frame on a side facing away from the gantry.

43. The machine tool of claim 42, wherein the workpiece table has two locations, each for supporting a respective pallet, wherein the pallet changer is configured to receive two pallets from the two locations of the workpiece table and to deliver two pallets to the two locations of the workpiece table, and wherein the pallet changer has a transfer unit, which can be pivoted about a vertical axis and has four coupling locations, which are each arranged to be coupled to a pallet to exchange the pallet between the workpiece table and a loading position on the pallet changer.

44. The machine tool of claim 43, wherein the workpiece table is movable in the Y direction into a transfer position, wherein in the transfer position a transfer of pallets between the workpiece table and the pallet changer is enabled, and wherein the pallet changer is positionally fixed in the Y direction in a state coupled to the frame.

45. The machine tool of claim 31, wherein the first tool spindle is configured to machine a workpiece on the second workpiece support location when in the crosswise operating mode.

46. The machine tool of claim 31, further comprising a plurality of tool change areas, a first tool change area associated with the first tool spindle and a second tool change area associated with the second tool spindle.

47. The machine tool of claim 31, further comprising a Z guide extending between the first tool spindle and a carriage.

48. The machine tool of claim 31, further comprising a Z guide extending between the second tool spindle and a carriage.

49. A machine tool having a normal and a crosswise operating mode comprising: a frame; a first tool spindle with a primary working position, the first tool spindle movable in an X and a Z direction; a second tool spindle with a second tool spindle primary working position, the second tool spindle movable in an X and a Z direction; a gantry, which is supported by the frame, that supports the first tool spindle and the second tool spindle on respective carriages; a workpiece table having workpiece support locations configured to respectively support workpieces; wherein the machine tool is switchable between the normal and the crosswise operating mode such that: in the normal operating mode, the first tool spindle is in the primary working position and associated with a first workpiece support location, and the second tool spindle is in the second tool spindle primary working position and associated with a second workpiece support location, and in the crosswise operating mode, the first tool spindle is in the second tool spindle primary working position and associated with the second workpiece support location, and the second tool spindle is outside of the secondary tool spindle primary working position.

50. The machine tool of claim 49, further comprising: a first tool holder associated with the first tool spindle, and a second tool holder associated with the second tool spindle. wherein the first tool spindle is vertically movable in a first tool change area to change a machining tool, and the second tool spindle is vertically movable in a second tool change area to change a machining tool.

51. The machine tool of claim 49, further comprising on the workpiece table at least one location configured to support at least one pallet.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0086] Further features and advantages of the present disclosure are disclosed by the following description of a plurality of preferred embodiments, with reference to the drawings, wherein:

[0087] FIG. 1: is a perspective, simplified rear view of a machine tool;

[0088] FIG. 2: is a rear, simplified view of the machine tool according to FIG. 1;

[0089] FIG. 3: is a simplified plan view of the machine tool illustrated in FIGS. 1 and 2;

[0090] FIG. 4: is a perspective view of a machine tool similar to FIG. 1, with a pallet changer;

[0091] FIG. 5: is a simplified top view of the machine tool according to FIG. 4;

[0092] FIG. 6: is a rear, simplified view of a further embodiment of a machine tool; and

[0093] FIG. 7: is a further view of the machine tool according to FIG. 6 in an alternative state.

EMBODIMENTS

[0094] FIG. 1, in connection with FIGS. 2 and 3, illustrates an exemplary embodiment of a machine tool, which is designated in its entirety by 10. The machine tool 10 comprises a frame 12 supporting a gantry 16. The gantry 16 includes a cross member 18 and side beams 20, 22. Side struts 26, 28 extend between the gantry 16 and the frame 12. The side struts 26, 28 connect a rear side (spindle side) of the gantry 16 and/or of its beams 20, 22 to elevated side profiles 32, 34 of the frame. A gantry recess 36 is formed on the gantry 16, through which a working space 38 is accessible. The gantry 16 delimits the working space 38.

[0095] In FIG. 2, a guide plane designated by 40 is indicated by a dashed line. The raised side profiles 32, 34 are raised relative to the guide plane 40. The side profiles 32, 34 stiffen the frame 12 and/or its base. The side struts 26, 28 provide a strong and rigid coupling between the side profiles 32, 34 and the gantry 16.

[0096] The gantry 16 supports a first tool spindle 46 and a second tool spindle 48. Accordingly, at least in the embodiment illustrated in FIGS. 1 to 3, the machine tool 10 is configured as a double spindle machine. The first tool spindle 46 is movable on a carriage 50 in a first direction 56 and, via the carriage 50, in a second direction 58. The second tool spindle 48 is movable on a carriage 52 in the first direction 56 and, via the carriage 52, in the second direction 58.

[0097] In FIG. 1, a Cartesian coordinate system X-Y-Z is shown for illustrative purposes. In the illustrated embodiment, the first direction 56 is parallel to the Z-axis. Further, the second direction 58 is parallel to the X-axis. A further, third direction (reference numeral 106) is parallel to the Y-axis. The Z-axis generally describes a vertical or height direction. The X-axis and the Y-axis generally describe horizontal axes oriented perpendicular to each other. Together, the X-axis and the Y-axis form a horizontal plane. The guide plane 40 (compare FIG. 2) is parallel to the X-Y horizontal plane.

[0098] It is understood that the coordinate system X-Y-Z and the axis designations and directions used herein are merely of exemplary nature and serve primarily illustrative purposes. They are therefore not to be understood to be limiting. It will therefore be understood that other coordinate systems and axis designations are also usable to describe the relationships between the components of the machine tool 10. The person skilled in the art may apply conceptual transformations to convert such coordinate systems into one another. Further, in the context of the present disclosure, ordinal numbers and/or enumerations (first, second, etc. elements) are used primarily for illustrative and distinguishing purposes and are therefore not to be understood in a limiting manner. Ordinal numbers do not necessarily imply a qualitative or quantitative order.

[0099] The first tool spindle 46 has a spindle axis 64 and a tool holder 70, which can be driven for rotation about the spindle axis 64, see also FIG. 2. The second tool spindle 48 has a spindle axis 66 and a tool holder 72, which can be driven in rotation about the spindle axis 66. The spindle axes 64, 66 result in a spindle distance 68 in the X-direction (second direction). In exemplary embodiments, the spindle spacing 68 is constant during machining so that the two tool spindles 46, 48 can be moved synchronously. In exemplary embodiments, this includes synchronous movement in the Z-direction (first direction). In this way, two workpieces can be machined simultaneously in an identical or nearly identical manner.

[0100] A Z-guide 82 extends between the tool spindle 46 and the carriage 50. A Z-guide 84 extends between the tool spindle 48 and the carriage 52. Both the carriage 50 and the carriage 52 are mounted on a guide 88 on the gantry 16, which extends in the X-direction (second direction). Furthermore, in FIG. 1 and FIG. 2 a primary part of a linear direct drive is indicated by 90. In the exemplary embodiment, the primary part 90 cooperates with corresponding secondary parts, one of which is arranged on the carriage 50 and one of which is arranged on the carriage 52. In this way, the tool spindles 46, 48 can be moved together and independently of each other in the second direction (X-direction) along the guide 88 at the gantry 16.

[0101] The machine tool 10 further comprises a workpiece table 100, which is arranged at least sectionally, for instance largely or completely, in the working space 38. In the exemplary embodiment according to FIGS. 1 to 3, the workpiece table 100 is configured as a cradle 102. The workpiece table 100 is translationally movable in a third direction 106 (Y-direction). The workpiece table 100 is configured to support workpieces. To this end, the workpiece table 100 exemplarily includes locations 114, 116, each of which forms a workpiece support. For example, the locations 114, 116 each comprise a rotatable rotary table 118, 120 for directly supporting workpieces or for supporting a pallet.

[0102] By way of example, the rotary tables 118, 120 each support a pallet 122, 124. The pallets 122, 124 function as workpiece carriers. The pallets 122, 124 may hold at least one workpiece that is secured to the pallet. Loading workpieces may comprise handling the pallets 122, 124, that is, loading the locations 114, 116 with pallets 122, 124, which are in turn loaded with workpieces. It will be understood that the machine tool 10 can in principle be operated without such pallets. Workpieces may be supported directly on the rotary tables 118, 120. Nevertheless, the pallets 122, 124 may facilitate an automated workpiece change. When the pallets 122, 124 are loaded with workpieces outside of the working space 38, non-productive times may be reduced. The pallets 122, 124 have coupling pieces 126, 128, compare FIG. 3. Via the coupling pieces 126, 128, a pallet changer can engage the pallets 122, 124 for handling them.

[0103] The rotary tables 118, 120 are pivotable and/or rotatable about axes 130, 132. The axes 130, 132 are also referred to as C-axes. In the orientation of the workpiece table 100 (the cradle 102) shown in FIG. 1, the axes 130, 132 are oriented parallel to the Z-axis. However, this orientation is dependent on the current pivot orientation of the workpiece table 100 with respect to the X-axis. The workpiece table 100 is mounted on a first carriage 140 and a second carriage 142. The carriages 140, 142 further define a pivot axis 144, which is also referred to as A-axis. The A-axis is parallel to the X-axis. The workpiece table 100 and consequently the rotary tables 118, 120 are pivotable about the A-axis. In the exemplary embodiment, the distance between the two C-axes 130, 132 corresponds to the selected spindle distance 68 between the two spindle axes 64, 66, at least in an exemplary operating mode for simultaneous machining of two workpieces.

[0104] In FIG. 2, blocks 148, 150 illustrate two translational drives for the workpiece table 100 for movement in the third direction 106 (Y-direction). By way of example, the carriages 140, 142 accommodate the drives 148, 150. This is conceivable, for example, with a direct drive or linear direct drive. However, it is also conceivable to make the carriages 140, 142 movable in the third direction 106 via screw drives (spindle drives) or the like. In certain embodiments, it is essential that each of the two carriages 140, 142 is assigned its own separate drive 148, 150. Accordingly, the workpiece table 100 is movable in the Y-direction according to the moving gantry principle. Via a suitable control of the two drives 148, 150, both carriages 140, 142 can be moved with high precision and in synchronism. In certain embodiments, the workpiece table 100, which is configured as a cradle 102, can be moved precisely in the Y-direction despite its considerable extension in the X-direction, while maintaining a desired degree of parallelism between the A-axis 144 and the X-direction. Further, in at least exemplary embodiments, high accelerations and travel speeds can be achieved with the two drives 148, 150.

[0105] The carriages 140, 142 also each accommodate a swivel drive 154, 156 as well as a pivot bearing 158, 160 for the swivel movement of the workpiece table 100, which is arranged as a cradle 102, about the swivel axis 144. Thus, two fundamentally independent drives, which are controlled synchronously, are also available for this degree of freedom. This configuration also contributes to the fact that, despite the considerable X-extension of the workpiece table 100 between the two carriages 140, 142, a highly precise movement and consequently a precise machining is possible. The two swivel drives 154, 156 allow high angular accelerations and angular velocities, at least in exemplary embodiments.

[0106] The carriages 140, 142 are each mounted on a longitudinal guide 162, 164 extending in the Y-direction. The longitudinal guides 162, 164 include guide rails 166, 168. The frame 12 supports the longitudinal guides 162, 164. The longitudinal guides 162, 164 are disposed within the side profiles 32, 34 of the frame. The longitudinal guides 162, 164 are adjacent the side profiles 32, 34.

[0107] In FIG. 1, two blocks designated by 176, 178 illustrate tool magazines for providing machining tools. The tool magazines 176, 178 are further detailed in FIGS. 2 and 3 with reference to schematic illustrations. The tool magazine 176 is associated with the first tool spindle 46. The tool magazine 178 is associated with the second tool spindle 48. The tool magazine 176 carries tool locations 182, 186 (FIG. 2). The tool magazine 178 carries tool locations 184, 188. The locations 182, 184, 186, 188 may be empty locations for supporting a tool from the tool spindles 46, 48 or locations loaded with tools for delivery to the tool holders 70, 72 of the tool spindles 46, 48.

[0108] The tool magazines 176, 178 are exemplarily configured as chain magazines, for instance as circulating chain magazines. Accordingly, suitable drives are provided for the tool magazines 176, 178. The tool magazines 176, 178 extend at least partially into magazine openings 192, 194 in the gantry 16, compare also FIG. 2 and FIG. 3. In this way, the tool magazines 176, 178 can be loaded from the side of the gantry 16 facing away from the working space 38. In exemplary embodiments, the tool magazines 176, 178 may extend outwardly through the magazine openings 192, 194.

[0109] According to another exemplary embodiment, the gantry 16 further comprises guide openings 198, 200, compare again FIG. 2. In the embodiment shown there, the guide openings 198, 200 are arranged below the magazine openings 192, 194 as seen from the frame 12. Through the guide openings 198, 200, an end face of the longitudinal guides 162, 164 and/or of their guide rails 166, 168 is accessible. In this way, this area including the carriages 140, 142 can be monitored, and furthermore maintenance work, inspection work and the like are simplified.

[0110] The work area 38 is accessible and visible through the central gantry recess 36. However, at least in exemplary embodiments, it is not intended to accomplish a workpiece change through the gantry recess 36. Instead, the workpiece change may be accomplished through the opposite side of the frame 12. Accordingly, the side of the machine tool 10 formed by the gantry 16 may be referred to as the operator side 206 and the side of the frame 12 facing away therefrom may be referred to as the loading side 208, at least in the example embodiment shown in FIG. 3.

[0111] At least in an exemplary embodiment, the tool change between the tool spindles 46, 48 and the tool magazines 176, 178 is performed without additional handling technology in the form of grippers, transfer units, robots, and similar mechanisms. Instead, the tool spindles 46, 48 are configured to perform a tool change using a pick-up process. To this end, the tool magazines 176, 178 are configured to provide vertical accessibility for the tool spindles 46, 48.

[0112] The tool spindles 46, 48 are not movable in the third direction (Y-direction). However, the tool magazines 176, 178, which are exemplarily configured as chain magazines, can be driven in such a way that a currently desired tool location 182, 184 can be provided in the required Y-position. However, the tool spindles 46, 48 are movable in the first direction (vertical) and the second direction (horizontal). In this way, for example, the first tool spindle 46 can move from its primary work area 212 (compare FIG. 3) in the X-direction into a tool change area 220 associated with the tool magazine 176 to assume a tool change position. Similarly, the second tool spindle 48 can move from its primary work area 214 in the X-direction into a tool change area 222 associated with the tool magazine 178 and assume a tool change position there. In the tool change position, the tool spindles 46, 48 may be moved vertically in the Z-direction to receive tools from and/or deliver tools to the tool locations 182, 184.

[0113] For the tool change, the two tool spindles 46, 48 leave their forced coupling with constant spindle distance 68. In certain embodiments, the two tool spindles can be moved separately and independently of each other. If desired tools are mounted at the tool receptacles 70, 72, synchronous machining can in turn be performed as required in the control-coupled state with constant spindle distance 68.

[0114] By way of example, FIGS. 2 and 3 illustrate that the tool magazines 176, 178 are arranged above (i.e., similar X-position, similar Y-position, different Z-position) the longitudinal guides 162, 164 of the workpiece table 100. This results in a favorable configuration of the working space 38, since it is not obstructed by the tool magazines 176, 178 and also not obstructed by the longitudinal guides 162, 164 and/or the carriages 140, 142. In certain embodiments, the transfer of the tools during the tool change takes place outside the working space 38 in the tool change area 220, 222 delimited therefrom. In principle, it is conceivable to provide partition walls between the working space 38 and the tool change area 220, 222.

[0115] With reference to FIG. 4 and FIG. 5, an exemplary embodiment with automated workpiece change is illustrated based on the configuration of the machine tool 10 already elucidated with reference to FIGS. 1 to 3. For the workpiece change, a pallet changer 230 is provided, which can be coupled to and/or moved towards the loading side 208 (compare also FIG. 3) of the frame 12.

[0116] The pallet changer 230 includes a frame base 232 that can be moved toward an end face 234 of the frame 12 in the third direction (Y-direction). Accordingly, the frame base 232 may comprise a chassis or guide units for Y movement. In an exemplary embodiment, the pallet changer 230 includes two locations 236, 238 that support pallets 244, 246 for pallet exchange. Accordingly, the pallets 244, 246 may be loaded with workpieces that are yet to be processed. The pallets 244, 246 correspond generally to the previously elucidated pallets 122, 124 on the workpiece table 100. The pallets 122, 124 and the pallets 244, 246 are interchangeable for workpiece exchange. The pallets 122, 124, 244, 246 each have a coupling piece 126, 128, 248, 250 on one of their end faces, which can be engaged by the pallet changer 230.

[0117] For the actual exchange movement (exchange of the pallets 122, 124 with the pallets 244, 246), it is not necessary to move the frame base 232 of the pallet changer 230 in the third direction (Y-direction) relative to the frame 12 of the machine tool 10. Instead, the workpiece table 100 can move in the Y-direction to a workpiece exchange position, in which the workpiece table 100 is adjacent to the pallet changer 230, compare FIG. 4. For the exchange, the pallet changer 230 includes a transfer unit 254 that can perform a combined lifting and swiveling movement, by way of example. In FIG. 4, the double arrow 256 illustrates the lifting movement (in the Z-direction). In contrast, the curved double arrow 258 illustrates the swiveling movement (about the Z-axis).

[0118] The transfer unit 254 has a total of four coupling locations 262, 264, 266, 268 so that a total of four pallets 122, 124, 244, 246 can be gripped and transferred by the transfer unit 254 via their coupling pieces 126, 128, 248, 250. By way of example, the pallets 122, 124, 244, 246 are lifted (Z-movement) by the transfer unit 254 and rotated 180 about the pivot axis 270 (compare FIG. 5) of the transfer unit 254. In this way, an exchange of the pallets 122, 124 with the pallets 244, 246 takes place.

[0119] With reference to FIG. 6 and FIG. 7, a further embodiment of a machine tool 10 is illustrated, which largely corresponds to the embodiment according to FIGS. 1 to 3. A modification is present in the configuration of the magazines for the tool change.

[0120] In a manner basically described hereinbefore, a first tool magazine 176 is associated with the first spindle 46 and a second tool magazine 178 is associated with the second spindle 48. However, the tool magazines 176, 178 are each associated with a magazine arrangement 282, 284. In addition to the tool magazine 176, the magazine arrangement 282 comprises a further tool magazine 276. In addition to the tool magazine 178, the magazine arrangement 284 comprises a further tool magazine 278. Similarly to the tool magazines 176, 178, the tool magazines 276, 278 comprise tool locations for providing or supporting tools.

[0121] The tool magazines 176, 178, 276, 278 are configured such that the first tool spindle 46 can approach both the tool magazine 176 and the tool magazine 276 to change tools therein using the pick-up process. Similarly, the second tool spindle can approach both the tool magazine 178 and the tool magazine 278 to change tools there using the pick-up process.

[0122] Since the tool spindles 46, 48 are not movable in the third direction (Y-direction), the two tool magazines 176, 276 of the magazine arrangement 282 as well as the two tool magazines 178, 278 of the magazine arrangement 284 are each offset from each other in the X-direction (second direction). The offset is adapted to the dimensions of the tool spindles 46, 48 so that tool locations of the tool magazines 176, 178, 276, 278 are accessible vertically (in the Z-direction) for the respectively associated tool spindle 46, 48. The respective lower tool magazine 276, 278, seen from the frame 12, is slightly offset with respect to the respective upper tool magazine 176, 178 in the direction towards the working area.

[0123] Furthermore, in addition to the magazine openings 192, 194 in the gantry 36 for the tool magazines 176, 178 already described, the embodiment illustrated with reference to FIGS. 6 and 7 has further magazine openings 292, 294, which allow access to the tool magazines 276, 278 from the operator side 206 (FIG. 3) through the gantry 16. It will be understood that the magazine openings 192, 292 as well as the magazine openings 194, 294 can in principle also be combined and thus each also form a common magazine opening for both magazines of the respective magazine arrangement 282, 284. Furthermore, FIGS. 6 and 7 also show the previously described guide openings 198, 200 at the gantry 16. Overall, therefore, good accessibility to the tool magazines 176, 178, 276, 278 and the carriages 140, 142 and/or the longitudinal guides 162, 164 from the operator side 206 is provided.

[0124] In this way, there is no need to change tools through the gantry recess 36. Accordingly, the tool change area 220, 222 may be separated from the work area 38 by walls or the like. The tool spindles 46, 48 are configured as pick-up spindles and can bypass or otherwise overcome such walls.

[0125] FIG. 7, in combination with FIG. 6, illustrates another exemplary feature of the machine tool 10. Basically, the other configurations according to FIGS. 1 to 5 may also comprise this function.

[0126] FIG. 6 illustrates a normal operating mode, in which the first tool spindle 46 is disposed in its primary work area 212 and consequently associated with the first rotary table 118 for machining workpieces there. Similarly, the second tool spindle 48 is disposed in its primary work area 214 and consequently associated with the second rotary table 120 for machining workpieces there.

[0127] Starting from this normal operating mode, FIG. 7 illustrates an operating mode, in which one of the two tool spindles can be operated crosswise. By way of example, in FIG. 7 the second tool spindle 48 is arranged in the tool change area 222. In principle, this can also relate to a parking position or service position.

[0128] There is now sufficient space in the second direction (X-direction) on the member 18 of the gantry 16 so that the first tool spindle 46 can now leave its original primary work area 212 (compare FIG. 6). In FIG. 7, the first tool spindle 46 is located in a secondary work area 302, in which the first tool spindle 46 is associated with the second rotary table 120 in order to machine workpieces there. It will be understood that the second tool spindle 48 cannot simultaneously be located in its secondary work area 304 associated with the first rotary table 118. However, this would be possible if the first tool spindle 46 is located in the tool change area 220.