Abstract:
The invention relates to a machine comprising a mechanical guide element ( 2   a,    2   b ) for guiding the displacement of a first ( 3   a,    3   b ) and a second device ( 4   a,    4   b ). The machine comprises a first drive device ( 5   a,    5   b,    10   a ) for displacing the first device ( 3   a,    3   b ) along the guide element ( 2   a,    2   b ), and a second drive device ( 6   a,    6   b,    10   b ) for displacing the second device ( 4   a,    4   b ) along the same guide element ( 2   a,    2   b ) as the first device ( 3   a,    3   b ). The mechanical construction of a machine is simplified due to said invention.

Description:
BACKGROUND OF THE INVENTION 
     The invention relates to a machine comprising a mechanical guide element. 
     In the case of machines such as e.g. machine tools, production machines and/or robots, each machine axle has a mechanical guide element for guiding the displacement of a single device such as e.g. a tool spindle or a workpiece holding device along the guide element. It is customary during machining e.g. of a workpiece that the tool spindle and/or the workpiece holding device is/are displaced by means of a respectively assigned drive apparatus. As well as these so-called NC (Numerical Control) guided machine axles, customary machines also possess so-called PLC (Programmable Logic Control) guided machine axles which enable the displacement e.g. of a tool changing device (tool changer). Should a tool be changed for a new machining process, e.g. from milling machining to boring machining, it is then customary that the milling cutter is first stopped and the tool spindle which drives the milling cutter is displaced along the guide element to a position at which a tool changing device can perform the tool change. However, this position is often relatively far from the actual position at which the milling machining takes place such that a relatively long time is required for the displacement of the tool spindle and thus the production process must be stopped for a longer time. 
     Moreover, in customary machines, the tool changing device folds from an idle position for changing the tool. In this case, the displacement process of the tool changing device is guided on a different guide element from the guide element of the tool spindle. This solution is mechanically relatively complex. 
     SUMMARY OF THE INVENTION 
     The object of the invention is to simplify the mechanical construction of a machine. 
     This object is achieved by a machine comprising a mechanical guide element for guiding the displacement of a first and a second device, characterized in that the machine has,
         a first drive apparatus for displacing the first device along the guide element, and   a second drive apparatus for displacing the second device along the same guide element as the first device.       

     Advantageous embodiments of the invention will become apparent from the dependent claims. 
     It has proved to be advantageous if the first drive apparatus and the second drive apparatus are embodied as linear motors. Linear motors represent drive apparatuses which are conventional in the case of machines. 
     In this context, it has proved to be advantageous if a displaceable primary part of the first drive apparatus and a displaceable primary part of the second drive apparatus use a shared stationary secondary part as a reaction part. If both the primary part of the first linear motor and the primary part of the second linear motor use a shared fixed secondary part as a reaction part, a further, normally essential, second reaction part can be omitted. 
     It has furthermore proved to be advantageous if the first device is embodied as a tool spindle or as a workpiece holding device. An embodiment of the first device as a tool spindle or as a workpiece holding device represents a conventional embodiment. 
     Moreover, it has proved to be advantageous if the second device is embodied as a tool changing device or as a workpiece transport device. An embodiment of the second device as a tool changing device or as a workpiece transport device represents a conventional embodiment. 
     It has furthermore proved to be advantageous if the detection of the position of the first and the second device is performed by means of a scale jointly used by the first and the second device. The use of a second scale can be omitted as a result of this measure. 
     It has moreover proved to be advantageous if the machine is embodied as a machine tool, production machine and/or as a robot. However, the invention can naturally also be used in other types of machines. 
    
    
     
       BRIEF DESCRIPTON OF THE DRAWING 
       Two exemplary embodiments of the invention are shown in the drawing and are explained in greater detail below. Therein: 
         FIG. 1  shows a machine according to the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     In  FIG. 1 , a machine  1  is represented in the form of a schematic view, which machine  1  is embodied in the context of the exemplary embodiment as a machine tool. The machine has a first device  3   a  which is embodied in the context of the exemplary embodiment as a tool spindle. The tool spindle drives a tool  13  in a rotary manner, which tool  13  is embodied in the context of the exemplary embodiment as a milling cutter. A workpiece  5  is machined with the help of tool  13 . The machine furthermore has a second device  4   a  which is embodied in the context of the exemplary embodiment as a tool changing device. The milling cutter can be replaced e.g. with a borer  11  with the help of the tool changing device and thus boring machining can be performed. 
     According to the invention, the machine has a mechanical guide element  2   a  for guiding the displacement of first device  3   a  and second device  4   a.  In this case, the displacement, in the context of the exemplary embodiment, is performed in the form of a vertical displacement in the direction of arrow  12 . The displacement of second device  4   a  thus takes place along the same guide element as the displacement of first device  3   a.  Both devices  3   a  and  4   a  thus use a shared guide element  2   a.  First device  3   a  is displaced along guide element  3   a  with the help of a first drive apparatus. Second device  4   a  is displaced along the same guide element  2   a  with the help of a second drive apparatus. In this case, the first drive apparatus and the second drive apparatus can conventionally be embodied with the help of rotary motors which displace the respectively assigned device via ball caster spindles. The machine thus no longer has a separate guide element for second device  4   a,  i.e. for the tool changing device, i.e. only one shared guide element  2   a  is present for the tool spindle and the tool changing device. This leads to a significant reduction in the design complexity since the tool changing device is no longer realized in the form of a separate machine axle. Moreover, the tool changing device can be moved close to the machining process for replacement of tool  13  and the tool change is performed close to the machining process. It is thus no longer necessary that the tool spindle has first to be moved into a position remote from the operational process for the tool change. 
     In the exemplary embodiment, the first drive apparatus and the second drive apparatus are advantageously embodied as linear motors. To this end, first device  3   a  is connected to displaceable primary part  5   a  of the first drive apparatus. Primary part  5   a  forms, together with stationary secondary part  10   a,  which is used as a reaction part, a first linear motor. Primary part  6   a  of the second drive apparatus forms, together with the same secondary part  10   a,  a second linear motor. First device  3   a  is connected to primary part  5   a  of the first drive apparatus and second device  4   a  is connected to primary part  6   a  of the second drive apparatus. Primary part  5   a  and primary part  6   a  thus use only one shared stationary secondary part as a reaction part, which has the advantage that the mechanical design can be yet further simplified by adjusting the construction lengths of primary parts  5   a  and  6   a  and the electric coils of the primary parts correspondingly to the required performance. As a result, the drive force and the power requirement of the drives can be optimized. An optimum thermal utilization of the linear motors can be achieved with the help of suitable overload or constant load primary parts. 
     The detection of the position of the first and second device is performed in this case by means of a scale  12   a  jointly used by first and second device  3   a  and  4   a,  which scale  12   a  is arranged along guide element  2   a.  Only a single scale is thus also required for determining the position of first device  3   a  and second device  4   a,  which further reduces the design complexity. 
     A second embodiment of the invention is furthermore shown in  FIG. 1 . As well as guide element  2   a  already described which runs vertically, the machine also has a guide element  2   b  running in the horizontal direction (see arrow  9 ), which guide  2   b  is realized in the context of the exemplary embodiment as a V-shaped groove. In the context of this embodiment of the invention, the first device is embodied as a workpiece holding device  3   b  in which workpiece  5  is clamped and which is displaced by means of primary part  5   b  of a first drive apparatus along guide element  2   b.  Primary part  5   b  forms, together with a secondary part  10   b,  which is used as a reaction part, a linear motor. With the help of a second drive apparatus, which is present in the context of this embodiment of the invention, in the form of primary part  6   b,  a second device  4   b,  which is present in the context of this embodiment of the invention and which is embodied as a tool transport device, is displaced along guide element  2   b.  Primary part  6   b  forms, together with secondary part  10   b,  a linear motor. Both primary parts  5   b  and  6   b  thus again use a shared secondary part  10   b  as a reaction part. 
     With the help of the invention, workpiece holding device  3   b  no longer has to be moved from the operational process along guide element  2   b  for a change to workpiece  5 , but rather workpiece transport device  4   b  can transport a workpiece  5  to be machined to the machining location and pick it up again from there. The same advantages are thus apparent in this second embodiment of the invention as already cited above in the case of the first embodiment. 
     Moreover, precisely as in the case of the first embodiment of the invention described above, the position of first device  3   b  and the position of second device  4   b  are also determined with the help of a jointly used scale  12   b.