Abstract:
The invention relates to a machine tool, especially a lathe, comprising a machine frame upon which a first and second spindle housing carrier are arranged in such a way that they can move in a direction Z in relation to each other; a first working spindle; a second working spindle; a first tool carrier which is associated with the first working spindle; a second tool carrier which is associated with the second working spindle, said first and second tool carriers being arranged on the same side of the spindle axis; and a machine control unit. In order to improve upon one such machine tool, whereby more work tools can be used simultaneously on workpieces, the spindle housing carriers extend sidewards away from the spindle housings and a third tool carrier, which can move at least in a direction X and which is associated with one of the working spindles, is provided between the spindle housing carriers of the first and second working spindles on a side of the spindle axis which is approximately opposite to the first and second tool carrier.

Description:
[0001]    The present disclosure relates to the subject matter disclosed in PCT application No. PCT/EP02/03355 of Mar. 26, 2002, which is incorporated herein by reference in its entirety and for all purposes. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0002]    The invention relates to a machine tool, especially a lathe, comprising a machine frame upon which a first spindle housing carrier and a second spindle housing carrier are supported in such a way that they can be moved in a Z direction in relation to each other, a first working spindle, which receives a first workpiece and is mounted rotatably about a spindle axis in a spindle housing seated on the first spindle housing carrier, a second working spindle, which is disposed coaxially with respect to the first working spindle, receives a second workpiece and is mounted rotatably about a spindle axis in a spindle housing seated on the second spindle housing carrier, a first tool carrier, which is movable in an X direction and is associated with the first working spindle for the machining of first workpieces disposed in the latter, a second tool carrier, which is movable in an X direction and is associated with the second working spindle for the machining of second workpieces disposed in the latter, the first and second tool carriers being disposed on the same side of the spindle axis, and a machine control unit for controlling the relative movements between the first workpiece and the tools of the first tool carrier and the second workpiece and the tools of the second tool carrier.  
           [0003]    Machine tools of this type are known from the prior art. With machine tools of this type, there is generally the requirement that the largest possible number of tools can be used simultaneously.  
           [0004]    The invention is therefore based on the object of improving a machine tool of the generic type in such a way that still more tools can be used simultaneously on the workpieces.  
         SUMMARY OF THE INVENTION  
         [0005]    This object is achieved in the case of a machine tool of the type described at the beginning according to the invention by the spindle housing carriers extending laterally away from the spindle housings and by a third tool carrier, which can be moved at least in an X direction and is associated with one of the working spindles, being provided between the spindle housing carriers of the first and second working spindles on a side of the spindle axes which is approximately opposite from the first and second tool carriers.  
           [0006]    The advantage of the solution according to the invention can be seen in that it allows the number of tools which can be used to be increased in a simple way.  
           [0007]    To allow the working spindles to move toward each other to the extent that the transfer of a workpiece from one spindle to the other is possible, it is necessary that the tool carrier does not extend very far in the Z direction, in order to keep the projection of the working spindle with respect to the spindle housing carriers as small as possible and consequently improve the rigidity of the machine.  
           [0008]    For this reason, it is preferably provided that the third tool carrier is disposed on an X slide, which is guided on an X slide base by X guides disposed in an X guiding plane perpendicular to the spindle axes.  
           [0009]    The advantage of the solution can be seen in that it allows the effect to be achieved that the third tool carrier with the X slide is slender in the Z direction, although an adequately large supporting surface can be realized in the X guiding plane to guide the X slide as rigidly as possible on the slide base.  
           [0010]    A still more advantageous embodiment of the solution according to the invention, in which still more tools can be brought into engagement, provides that a fourth tool carrier is disposed between the first and second spindle housing carriers and that the third tool carrier is associated with the first working spindle and the fourth tool carrier is associated with the second working spindle. Consequently, altogether four tool carriers are available, so that in each case two tools can be brought into engagement on the first workpiece and two tools can be brought into engagement on the second workpiece.  
           [0011]    It is particularly advantageous if the fourth tool carrier is disposed on an X slide which is guided on an X slide base in X guides disposed in the X guiding plane perpendicular to the spindle axes. Consequently, the fourth tool carrier also extends little in the Z direction, so that once again this requires the spindles to project as little as possible beyond the spindle housing carrier slides.  
           [0012]    With regard to the way in which the third and fourth tool carriers are disposed, no further details have been specified so far. So it would be conceivable, for example, to dispose the third and fourth tool carriers on a common X slide.  
           [0013]    However, it is particularly advantageous with regard to production flexibility if the third tool carrier and the fourth tool carrier are respectively seated on an X slide of their own.  
           [0014]    Furthermore, there are various possible ways of disposing the X slides respectively associated with the tool carriers. A simple solution provides that the X slide of the third tool carrier and the X slide of the fourth tool carrier are seated on a common X slide base. This solution has the advantage that it provides a solution of a simple structural design for disposing the third and fourth tool carriers.  
           [0015]    In this case, the X slide base may either be disposed in a stationary manner on the machine frame or still be displaceable, for example, in the Z direction or in the Y direction.  
           [0016]    Another advantageous solution provides that each of the X slides has an X slide base of its own. This solution has the advantage that it increases the flexibility, in particular since, for example, each slide base can be formed in such a way that it is displaceable in the Z direction or Y direction.  
           [0017]    With regard to the forming of the X guides in the X guiding plane, no further details have been specified in connection with the explanation so far of the individual exemplary embodiments. To obtain an adequately rigid support in relation to the X guiding plane, it is preferably provided that the X guides have in a transverse direction running in the X guiding plane and transversely to the X direction a spacing from each other which corresponds at least to an effective diameter of the workpiece receptacle in the respective working spindles.  
           [0018]    As an alternative or in addition to this, an advantageous dimensioning specification for the support in the X guiding plane provides that the X guides have in a transverse direction running in the X guiding plane and transversely to the X direction a spacing from each other which is of the order of magnitude of an extent of the respective tool carrier in the transverse direction.  
           [0019]    The tool carrier is in this case preferably formed as a tool turret, so that the spacing in the transverse direction approximately corresponds for example in this case to the extent of the turret housing in the transverse direction.  
           [0020]    A particularly advantageous form of construction which is as slender as possible in the Z direction provides that the X slide has a slide body which is guided by the X guides close to its edge sides that are spaced apart in the transverse direction.  
           [0021]    An extremely suitable solution provides that the slide body is guided by X guides seated on edge surfaces running transversely to the X guiding surface.  
           [0022]    With regard to the forming of the X slide base, it is conceivable—as already mentioned—to dispose the slide base in a stationary manner.  
           [0023]    A particularly advantageous solution provides, however, that the X slide base is formed as a Z slide guided by Z guides.  
           [0024]    The Z slide is in this case preferably guided by a Z guide on the spindle housing carrier which has its working spindle associated with the tool carrier disposed on the Z slide.  
           [0025]    A Z guide of this type can be formed in a wide variety of ways. A particularly advantageous solution provides that the Z guide has an arm which extends from the Z slide in the direction of the spindle housing carrier guiding the latter.  
           [0026]    To achieve particularly advantageous guidance, it is preferably provided that the arm extends beyond the spindle housing carrier, so that a great path can be realized by the Z guidance in the Z direction.  
           [0027]    The Z guidance further comprises also a Z guiding receptacle, the arm extending through the Z guiding receptacle for said arm which is disposed on the spindle housing carrier guiding said receptacle. This provides a solution for the guidance of the Z slide which can be realized particularly easily and is stable.  
           [0028]    With regard to a drive of the Z slide, so far no further details have been specified. The drive could, for example, be effective in relation to the machine frame. A particularly advantageous solution provides that a Z axial drive is provided, with which the Z slide can be moved in relation to the respective spindle housing carrier.  
           [0029]    It is particularly suitable in this case if the Z axial drive is effective between the arm and the spindle housing carrier guiding the latter, so that the Z position of the Z slide can always be defined in relation to the respective spindle housing carrier.  
           [0030]    With regard to the drive motor required for the Z axial drive, it is particularly advantageous if this drive motor for the Z axial drive is held by the arm, so that a particularly simple and space-saving construction is available for disposing the drive motor.  
           [0031]    With regard to how the X axial drive motor is disposed, likewise no further details have been specified in connection with the explanation so far of the individual exemplary embodiments. The X axial drive motor could, for example, be disposed directly on the X slide or the slide base of the same.  
           [0032]    A particularly advantageous solution provides, however, that an X axial drive motor for the X slide is disposed at an end of the arm opposite from the Z slide and is consequently disposed in a position in which it does not take up any space in the region of the in any case confined working space.  
           [0033]    To drive the X slide with an X drive motor of this type, it is preferably provided that a drive train extends along the arm between the X axial drive motor and the Z slide and can consequently be guided in an advantageous way with respect to the Z slide and X slide.  
           [0034]    A particularly suitable solution provides that the drive train is led through the arm and is consequently at the same time also protected by the arm.  
           [0035]    As an alternative or in addition to the guidance of the Z slide on the corresponding spindle housing carrier, a preferred solution provides that the Z slide is supported by at least one guiding element on a Z guide provided on the machine frame. This solution has the advantage that a direct and stable support on the machine frame, in particular close to the tool carrier, can be realized in this way.  
           [0036]    It is even better if the Z slide is guided by a guiding element respectively on one of two Z guides disposed on the machine frame.  
           [0037]    For the support of the Z slide, it is preferably provided in this case that at least one of the guiding elements is guided on the corresponding Z guide with a guiding length in the Z direction which is less than a guiding length accepting tilting moments of the Z slide, so that an extent of the Z slide which is as small as possible in the Z direction can be realized in this way.  
           [0038]    It is particularly advantageous in this case if at least one of the guiding elements is guided on the corresponding Z guide in such a way that the latter only accepts forces lying in planes running transversely to the Z direction.  
           [0039]    With regard to the Z guides, it is conceivable to provide special Z guides for the Z slide.  
           [0040]    A particularly advantageous solution provides, however, that the Z guides disposed on the machine frame are also formed as Z guides of a further slide guided on the machine frame, so that the Z guides can be multiply used, resulting in a simpler and clearer construction of the machine tool according to the invention.  
           [0041]    With regard to the mobility of the working spindles in relation to one another, so far no details have been specified. So a particularly advantageous embodiment of the machine tool according to the invention provides that at least one of the spindle housing carriers forms a spindle housing carrier slide which can be made to move in the Z direction for the working spindle carried by said slide, so that the working spindles can be advantageously made to move in the Z direction by this spindle housing carrier slide.  
           [0042]    It is particularly advantageous if both spindle housing carriers are formed as spindle housing carrier slides which can be made to move in the Z direction.  
           [0043]    With regard to the guidance of the spindle housing carrier slides in the Z direction, so far no further details have been specified.  
           [0044]    So a particularly advantageous solution provides that a Z guiding plane, in which the Z guides for the spindle housing carrier slide lie, runs transversely to a setting-up area of the machine frame. By being disposed in this way, there is the advantage that the spindle housing carrier slides can consequently be disposed in an easily accessible and space-saving manner.  
           [0045]    With a solution of this type it is preferably provided that the Z slide is guided at least on one of the two spaced-apart Z guides for the respective spindle housing carrier slide. This solution has not only the advantage that it is much simpler, but also the advantage that inaccuracies in the relative positioning of the Z slide with respect to the respective working spindle have less of an effect in the Z guides, since the Z guides fix the way in which both the working spindle and the Z slide are disposed.  
           [0046]    Particularly advantageous support is achieved when the Z slide is guided on both spaced-apart Z guides for the respective spindle housing carrier slide, since optimum support of the Z slide as close as possible to the tool carrier can be achieved in this way.  
           [0047]    With respect to the function of the machine tool according to the invention, so far no further details have been specified.  
           [0048]    So a particularly preferred solution provides that, in a machining mode, the third tool carrier can be made to move in relation to the first working spindle and the fourth tool carrier can be made to move in relation to the second working spindle into the Z positions required for the machining of the first workpiece and second workpiece, respectively.  
           [0049]    With regard to the first tool carrier, no further details have been specified in this connection. It is particularly advantageous in this case if, with the machine control unit in the operating mode, the first tool carrier and the first working spindle can be made to move in relation to each other into the Z positions required for the machining of the first workpiece.  
           [0050]    Consequently, a wide variety of solutions are conceivable for the machining of the first workpiece.  
           [0051]    For example, it is conceivable to dispose the first working spindle in a stationary manner and consequently to move the first tool carrier and the third tool carrier in relation to the stationary first working spindle.  
           [0052]    Another advantageous solution envisages disposing the first tool carrier in a stationary manner and then moving the first working spindle in relation to the first tool carrier and additionally the third tool carrier in relation to the first working spindle, in which case, when there are movements of the first working spindle in relation to the first tool carrier, on account of the direct coupling with the first spindle housing carrier slide the third tool carrier is moved as it were “piggyback” with respect to the first working spindle together with the latter, and consequently the control of the third tool carrier works with the position of the working spindle in the Z direction as a reference variable and does not expressly have to take this into account.  
           [0053]    To increase further the multitude of functional possibilities, it is for instance also conceivable, however, to form movably in each case in the Z direction not only the first tool carrier but also the first working spindle and the third tool carrier in relation to the first working spindle, in which case the third tool carrier continues as before to be moved “piggyback” with respect to the first working spindle.  
           [0054]    Furthermore, it is advantageous if, with the machine control unit in the machining mode, the second tool carrier and the second working spindle can be made to move in relation to each other into the Z positions required for the machining on the second workpiece.  
           [0055]    A wide variety of solutions are also conceivable for the machining of the second workpiece, so it would be conceivable to dispose the second tool carrier in a stationary manner and to move the second working spindle in relation to the second tool carrier and additionally move the fourth tool carrier in relation to the second working spindle, said fourth tool carrier likewise being movable “piggyback” with the second working spindle.  
           [0056]    Since one of the working spindles must be movable in the Z direction for the transfer of the workpiece between them, a further possibility would be to dispose the fourth tool carrier in a stationary manner and not to make it movable in the Z direction, so that in this case the second working spindle must be movable in relation to the fourth tool carrier in the Z direction and in addition the first tool carrier must be movable in relation to the second working spindle.  
           [0057]    The machine tool according to the invention may in this case also combine all the alternatives presented above in connection with the machining of the first and second workpieces with one another and it is also possible to keep the first working spindle movable in the Z direction, while the second working spindle is stationary in the Z direction.  
           [0058]    An alternative, but likewise advantageous solution provides that the third tool carrier carries tools which can be used at least on one of the workpieces, that, with the machine control unit in a machining mode, one of the working spindles is movable in relation to the third tool carrier in a way corresponding to the Z positions required for the machining of the respective workpiece by means of the tool provided on the third tool carrier for this workpiece, and what is more the tool carrier likewise associated with this working spindle is movable in relation to this working spindle in a way corresponding to the Z positions required for the machining of this workpiece by means of a tool provided on this tool carrier, likewise associated with the working spindle.  
           [0059]    The advantage of this solution is that the third tool carrier can be stationary and both the corresponding working spindle and the corresponding further tool carrier move.  
           [0060]    This solution has the advantage in particular that only two Z axes are required for the machining of a workpiece with two tool carriers.  
           [0061]    It is particularly advantageous if, with the machine control unit in the machining mode, the first working spindle is movable in relation to the third tool carrier and the second working spindle is movable in relation to the fourth tool carrier into the Z positions required for the machining of the first workpiece and second workpiece, respectively.  
           [0062]    Furthermore, it is advantageously provided that the first tool carrier is movable in relation to the first working spindle and the second tool carrier is movable in relation to the second working spindle into the Z positions required for the machining.  
           [0063]    No further details have been specified in connection with the explanation so far of the tool carriers.  
           [0064]    For example, tool carriers of this type could be individual tool carriers.  
           [0065]    However, it is particularly advantageous if these tool carriers are formed as multiple tool carriers, it being possible for a multiple tool carrier of this type to be a linearly displaceable tool carrier or a turret with a turret head which is rotatable about an axis with respect to a housing.  
           [0066]    Further features and advantages of the solution according to the invention are the subject of the description which follows and of the graphic representation of some exemplary embodiments.  
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0067]    [0067]FIG. 1 shows a section along line  1 - 1  in FIG. 3 through a first exemplary embodiment of a machine tool according to the invention;  
         [0068]    [0068]FIG. 2 shows a plan view in the direction of the arrow X in FIG. 3 with the machine bed partly broken away;  
         [0069]    [0069]FIG. 3 shows a section along line  3 - 3  in FIG. 1;  
         [0070]    [0070]FIG. 4 shows a section along line  4 - 4  in FIG. 1;  
         [0071]    [0071]FIG. 5 shows a section similar to FIG. 1 through a second exemplary embodiment and  
         [0072]    [0072]FIG. 6 shows a plan view similar to FIG. 2 in the case of the second exemplary embodiment. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0073]    An exemplary embodiment of a lathe according to the invention, represented in FIGS.  1  to  4 , comprises a machine frame, designated overall by  10 , with a machine bed  12 , which is formed for example as a hollow body elongated in the longitudinal direction  13 , as represented in FIGS. 1, 3 and  4 .  
         [0074]    Provided on a front side  14  of the machine bed  12  are two Z guides  16   a  and  16   b,  which run parallel to the longitudinal direction  13  of the machine bed and lie in a first Z guiding plane  20 , which runs transversely to a setting-up area  22  on which the machine frame  10  stands. In this case, the Z guiding plane  20  also runs parallel to the longitudinal direction  13  of the machine bed  12 .  
         [0075]    On the Z guides  16   a  and  16   b,  a first spindle housing carrier slide  30  is respectively guided by two spaced-apart pairs of guiding carriages  32   a  and  34   a,  and  32   b  and  34   b,  respectively, so that the spindle housing carrier slide  30  can be moved in a Z direction along the Z guides  16  and is supported on the latter against tilting.  
         [0076]    The first spindle housing carrier slide  30  carries a spindle housing  36 , in which a first working spindle  40  is mounted rotatably about a first spindle axis  42  and can be driven by a spindle drive, preferably a spindle motor  44  integrated into the spindle housing  36 .  
         [0077]    Disposed lying opposite the first spindle housing carrier slide  30  is a second spindle housing carrier slide  50 , which for its part is movably guided in the Z direction by two spaced-apart sets of guiding carriages  52   a  and  54   a,  and  52   b  and  54   b,  respectively, likewise on the Z guides  16   a  and  16   b,  respectively, and is supported against tilting.  
         [0078]    The second spindle housing carrier slide  50  also carries a second spindle housing  56 , in which a second working spindle  60  is mounted rotatably about a second spindle axis  62  and can be driven, preferably by a spindle motor  64 .  
         [0079]    In this case, the second spindle axis  62  is aligned coaxially with respect to the first spindle axis  42 .  
         [0080]    In this case, the working spindles  40  and  60  are preferably disposed in such a way that the spindle heads  46  and  66  are facing each other and have workpiece receptacles  48  and  68 , respectively, in which a first workpiece W 1  and a second workpiece W 2  can be respectively received and fixed for turning on the lathe.  
         [0081]    Furthermore, with coaxial alignment of the spindle axes  42  and  62 , the provision that the spindle housing carrier slides  30  and  50  can be made to move means that the two working spindles  40  and  60  can be made to move toward each other to the extent that a transfer of the workpiece W 1  held in the first workpiece receptacle  48  into the second workpiece receptacle  68  of the second working spindle  60  is possible, with a change of the clamped side, so that a workpiece W can be machined overall as workpiece W 1  on a first side and as workpiece W 2  on a second side, and consequently can be machined completely.  
         [0082]    As represented in FIG. 3, provided on an upper side  70  of the machine bed  12  are two Z guides  72   a  and  72   b,  which likewise run parallel to the Z direction and lie in a second Z guiding plane  74 , which for its part runs transversely to the first Z guiding plane  20  and approximately parallel to the setting-up area  22 .  
         [0083]    As represented in FIG. 1, guided on the Z guides  72   a  and  72   b  on the upper side  70  of the machine bed  12  are a first tool slide carrier  80  and a second tool slide carrier  90 , which for their part once again form a slide carrier for a first tool slide  100  and a second tool slide  110 , respectively, the tool slide  100  or  110  guided on the respective tool slide carrier  80  or  90  being guided by X guides lying in an X guiding plane  82  or  92 , respectively, for example represented by the X guides  94   a  and  94   b,  the X guiding planes  82  and  92  running approximately perpendicular to the spindle axes  42  and  72 , respectively.  
         [0084]    Disposed on the tool slides  100  and  110  are tool carriers  120  and  130 , respectively, which are formed for example as tool turrets, the turret housings  122  and  132  of which are seated on the respective tool carriage  100  or  110  and on the turret housing  122  or  132  of which there is respectively seated a turret head  124  or  134 , which is rotatable about an axis of rotation  126  or  136  with respect to the turret housing  122  or  132 , respectively, the axes of rotation  126  and  136  running approximately parallel to the spindle axes  42  and  62 , respectively.  
         [0085]    Provided circumferentially on the turret heads  124  and  134  are receptacles for tools  128  and  138 , respectively, with which the workpieces W 1  and W 2  can be respectively machined.  
         [0086]    According to the invention, in this case, the first tool carrier  120  is associated with the first working spindle  40  and the second tool carrier  130  is associated with the second working spindle  60 , that is to say that all the tools  128  of the first tool carrier  120  are provided for the machining of the first workpiece W 1  in the first working spindle  40 , while all the tools  138  of the second tool carrier  130  are provided on the workpiece W 2  held in the second working spindle  60 .  
         [0087]    According to the invention, in the case of the first exemplary embodiment, a third tool carrier  140 , which is associated with the first working spindle  40 , and a fourth tool carrier  150 , which is associated with the second working spindle  60 , are provided in addition to the first tool carrier.  
         [0088]    Both the third tool carrier  140  and the fourth tool carrier  150  are formed as tool turrets and comprise a turret housing  142  or  152 , respectively, on which a turret head  144  or  154  is mounted rotatably about a turret axis  146  or  156 , respectively.  
         [0089]    Respectively disposed on the turret head  144  or  154  are tools  148  and  158 , the tools  148  of the turret head  144  being provided for the machining of the workpiece W 1  and the tools  158  of the turret head  154  being provided for the machining of the workpiece W 2 . Consequently, the entire third tool carrier  140  is associated with the first working spindle  40  and the entire fourth tool carrier  150  is associated with the second working spindle  60 .  
         [0090]    The third tool carrier  140  and the fourth tool carrier  150  are in this case seated on an X slide  160  or  170 , respectively associated with them, and these X slides  160  and  170  are for their part again guided on a Z slide  180  or  190  respectively serving as a base body for them, the Z slides  180  and  190  in each case having only two guiding carriages  182   a  and  182   b  or  192   a  and  192   b,  respectively, and being guided by these on the Z guides  16   a  and  16   b  for the spindle housing carrier slides  30  and  50 .  
         [0091]    Since the support of the Z slides  180  and  190  by only two guiding carriages  182   a  and  182   b  or  192   a  and  192   b  on the Z guides  16   a  and  16   b,  respectively, does not offer adequate resistance to tilting, but can only accept supporting forces which lie in planes  183  and  193  running transversely to the Z guides  16   a, b,  each of the Z slides  180  and  190  is provided with an arm  184  or  194 , respectively, which extends from the respective Z slide  180  or  190  in the direction of the spindle housing carrier slide  30  or  50 , respectively, which carries the working spindle  40  or  60  associated with the third tool carrier  140  or fourth tool carrier  150 , respectively.  
         [0092]    The respective arm  184  or  194  is in this case preferably formed as a sleeve, which is passed through by a longitudinal guide  186  or  196 , for example a sleeve guide, in the respective spindle housing carrier slide  30  or  50  and is guided in the latter in the Z direction in a linearly movable manner in relation to the spindle housing carrier slide  30  or  50 , respectively, so that the guidance of the arm  184  or  194 , or rather of the sleeve  184  or  194  in the corresponding sleeve guide  186  or  196 , in the corresponding spindle housing carrier slide  30  or  50  brings about additional support of the respective Z slide  180  or  190 , and consequently overall together with the guiding carriages  182   a, b  and  192   a, b  stable tripod-like support against tilting of the slides  180  and  190  in the direction of the associated spindle housing carrier slide  30  or  50  or away from the latter, and this altogether threefold guidance of the Z slide  180  or  190  means that support of this Z slide on only one guiding carriage  182   a, b  or  192   a, b  is adequate, so that the Z slide  170  or  180  must only have an extent in the Z direction adequate for receiving a guiding carriage  182   a, b  or  192   a, b  that does not provide support against tilting.  
         [0093]    The extent of the Z slides in the Z direction is preferably at most half the extent of the respective spindle housing carrier slide  30  or  50  in the region of the guiding carriages  32  and  34  or  52  and  54 , respectively, in the Z direction.  
         [0094]    This allows the spindle housings  36  and  56  with the working spindles  40  and  60  to be disposed on the spindle housing carrier slides  30  and  50  in such a way that the working spindles project as little as possible with respect to the spindle housing carrier slides  30  and  50  up to the respective workpiece receptacle  48  or  68 , respectively.  
         [0095]    Furthermore, held on the respective arm  184  or  194 , to be precise at an end opposite from the respective Z slide  180  or  190 , is a drive carrier  188  or  198 , respectively, on which there can be mounted a Z axial drive  200  or  210 , which drives an adjusting spindle  202  or  212 , which runs with its axis parallel to the Z direction and the spindle nut  204  or  214  of which is firmly held on the associated spindle housing carrier slide  30  or  50 , respectively.  
         [0096]    With a threaded spindle drive  202 ,  204  or  212 ,  214  of this type, the arm  184  or  194  can be positioned in a controlled manner in relation to the spindle housing carrier slide  30  or  50 , respectively, completely independently of the Z position of the same in relation to the machine frame  10 , the required Z axial drive  200  or  210  not requiring any space between the spindle housing carrier slides  30 ,  50 , but it instead being possible for it to be disposed on an outer side of the arms  184  or  194 , respectively, facing away from a working space A.  
         [0097]    In addition, respectively provided on the drive carrier  188  or  198  is an X axial drive  206  or  216 , which is capable by means of a drive shaft  208  or  218  running through the respective arm  184  or  194  of driving an adjusting mechanism (not represented in the drawing) for the X slide  160  or  170 , with which the latter can be moved with respect to the respective Z slide  180  or  190 .  
         [0098]    For guiding the X slides  160  and  170  in relation to the Z slides  180  and  190 , the X slides  160  and  170  are provided, as represented in FIG. 2, on edge areas  162   a, b  and  172   a, b  of their edge sides  164   a, b  and  174   a, b  with X guides  166   a, b  and  176   a, b,  respectively, which are seated on said edge areas and interact with guiding carriages  168   a, b  and  178   a, b,  respectively, the guiding carriages  168   a, b  and  178   a, b  being disposed in a stationary manner on the respective Z slide  180  or  190 .  
         [0099]    In this case, the guiding carriages  168   a, b  and  178   a, b  are preferably held on guiding end pieces  169   a, b  or  179   a, b  reaching beyond the X slides  160  and  170  in the region of their edges  164   a, b  and  174   a, b,  so that the Z slides  180  and  190  are as slender as possible in the Z direction.  
         [0100]    Consequently, the X guides  166   a, b  and  176   a, b  respectively fix X guiding planes  167  and  177  which run perpendicularly to the Z direction, and consequently make it possible to guide the respective X slide  160  or  170  stably with respect to tilting on the Z slide  180  or  190  in the X direction, the spacing between the X guides  166   a  and  166   b  or  176   a  and  176   b  not having any adverse effects on the extent of the respective Z slides  180  and  190  in the Z direction, since the X guiding planes  167  and  177  run perpendicularly to the Z direction.  
         [0101]    Consequently, the alignment of the X guiding plane  167  or  177  in relation to the respective Z slide  180  or  190  also contributes to obtaining altogether a slide system for the respective tool carrier  140  or  150  which has in the Z direction an overall extent which corresponds at most to half the extent of the spindle housing carrier slides  30  and  50  in the Z direction.  
         [0102]    The lathe according to the invention further comprises, as represented in FIGS. 3 and 4, a machine control unit  230 , with which a drive motor  240  of a first linear drive  242  for the first spindle housing carrier slide  30  can be activated and also a drive motor  250  of a second linear drive  252  for the second spindle housing carrier slide  50 , so that both spindle housing carrier slides  30  and  50  are displaceable in a controlled manner in the Z direction.  
         [0103]    In addition, the machine control unit  230  can be used to activate the Z axial drives  200  and  210 , by means of which the Z slides  180  and  190  can be positioned in relation to the respective spindle housing carrier slide  30 ,  50  on the basis of the threaded spindle drives  202 ,  204  and  212 ,  214 , to be precise in relation to the respective working spindle  40  or  60 , the positioning of the tools  148  or  158  in relation to the respective first workpiece W 1  or second workpiece W 2  being independent of the Z position of the working spindles  40  and  60 , so that, for the machining of the workpieces W 1  and W 2  by the tools  148  and  158 , the machine control unit  230  merely has to activate the Z axial drive  200  or  210 , respectively.  
         [0104]    The displaceability of the working spindles  40  and  60  in relation to each other can consequently not only be used for transferring the workpiece W from the first working spindle  40  to the second working spindle  60 , or vice versa, but also be used for providing that, for example for machining the first workpiece with a tool  128  of the first tool carrier  120 , the Z axial movement is performed by movement of the spindle housing carrier slide  30  in relation to the machine bed  12 , so that it is not necessary for the first tool carrier  120  to be made to move in the Z direction by means of the first tool slide carrier  80 .  
         [0105]    In the same way, for machining the second workpiece W 2  by means of a tool  138  of the second tool carrier  130 , the Z movement can likewise be performed by making the working spindle  60  move together with the spindle housing carrier slide  50  in the Z direction, so that the tool slide carrier  90  itself likewise does not have to be made to move.  
         [0106]    Finally, however, the machine control unit  230  also allows displacement of the tool slide carriers  80  and  90  in the Z direction by means of threaded spindle drives, the threaded spindle drive  254  for the second tool slide carrier  90  being represented in FIGS. 3 and 4.  
         [0107]    Furthermore, the machine control unit  230  makes it possible to control the working spindles  40 ,  60  of the movements of the X slides  100  and  110  and also  160  and  170  in the X direction, that is to say transversely to the spindle axes  42  and  62 , and finally also to control the turret heads  124 ,  134 ,  144  and  154  by rotating the same about their respective axis  126 ,  136 ,  146  and  156 .  
         [0108]    A second exemplary embodiment of a lathe according to the invention, represented in FIGS. 5 and 6, represents a simplified embodiment of the first exemplary embodiment, the same parts being provided with the same reference numerals, so that, with regard to the description of the same, reference can be made to the first exemplary embodiment in full.  
         [0109]    By contrast with the first exemplary embodiment, in the case of the second exemplary embodiment, representing a simplified embodiment, the X slides  160  and  170  are not disposed on corresponding Z slides, but instead are seated on a common slide base  260 , which is disposed in a stationary manner on the machine bed  12  and is connected to the latter.  
         [0110]    The slide base  260  has for its part the end pieces  169   a, b  and  179   a, b,  seated on which are the guiding carriages  168   a, b  and  178   a, b,  in which the X guides  166   a, b  and  176   a, b  are guided, which for their part once again are seated on the edge sides  164   a, b  and  174   a, b  of the X slides  160  and  170 , respectively, and guide the latter, the X guiding planes  167  and  177  in the same way as in the case of the first exemplary embodiment likewise being perpendicular to the spindle axes  42  and  62 , respectively.  
         [0111]    Consequently, the X slides  160  and  170  together with the slide base  260  are likewise constructed in the Z direction in such a way that their extent in the Z direction is less than two thirds of the extent of the spindle housing carrier slides  30  and  50  in the Z direction.  
         [0112]    In the case of the second exemplary embodiment of the lathe according to the invention, it is absolutely necessary for the machining of the workpieces W 1  and W 2  to move the working spindles  40  and  60  in relation to the tools  148  and  158  of the third tool carrier  140  and fourth tool carrier  150 , respectively, to allow the workpieces W 1  and W 2  to be machined Z-dependently.  
         [0113]    In addition, it is necessary in the case of the second exemplary embodiment to move the first tool carrier  120  and the second tool carrier  130  in relation to the working spindles  40  and  60 , so that Z-dependent machining of the workpieces W 1  and W 2  is likewise possible with the tools  128  and  138  of said tool carriers.  
         [0114]    Otherwise, the machine control unit of the second exemplary embodiment controls the X movements of the X slides  100 ,  110 ,  160  and  170  in the same way as described in connection with the first exemplary embodiment.