Abstract:
There is provided a punch tool lift spindle. More specifically, in one embodiment, a punching machine including a tool bearing, a drive spindle coupled to the tool bearing, and a drive system configured to move the tool bearing axially along a lifting axis and to rotate the tool bearing about the lifting axis, the drive system including a motor system comprising a stator and a rotor internally coupled to the stator and a spindle nut coupled to the rotor and cooperating with the drive spindle, wherein the spindle nut is at least partially disposed within the stator.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application is a continuation of, and claims priority under 35 U.S.C. §120 to PCT/EP2005/005636, filed on May 25, 2005, and claims priority under  35  U.S.C. §119 from European application EP 04 012 523.9, filed May 27, 2004. Both of these references are hereby incorporated by reference. 
     
    
     TECHNICAL FIELD  
       [0002]     This invention relates to industrial equipment, and more particularly to machines configured to cut or punch workpieces, such as metal sheets.  
       BACKGROUND  
       [0003]     As those of ordinary skill in the art will appreciate, punching machines may be employed to punch holes or other cut-outs from a workpiece (e.g., a metal sheet). Typically, punching machines include a tool bearing for a punching tool and a rotary/lifting drive, which moves the tool bearing back and forth along a lifting axis to a working area of the punching machine. Also, the tool bearing is rotatably adjustable about the lifting axis. The punching machine may also include a motor-driven spindle transmission provided with a drive control system. Typically, a rotary/lifting drive having two electric drive motors is provided for the tool bearing of a punching machine. Both drive motors may be arranged laterally next to a drive spindle, which in turn runs in the direction of a lifting axis of the tool bearing. One of the drive motors serves for workpiece punching and for that purpose is connected via a belt drive to a lifting spindle nut disposed on the drive spindle. By driving this spindle transmission in one direction of rotation, the tool bearing (and hence the attached punching tool) is moved with working strokes towards the workpiece to be processed and then by reversing the motor, the tool bearing is moved in the opposite direction. The second drive motor in a conventional punching machine is intended for rotary adjustment of the tool bearing and the punching tool. This drive motor is connected via another belt drive to enable rotation of the punching tool relative to the lifting axis. A more efficient punching tool would be desirable.  
       SUMMARY  
       [0004]     In one embodiment, the spindle transmission for stroke movement of the tool bearing in the radial direction lies inside the stator of the lifting drive motor. Additionally or alternatively, the driving element for rotary adjustment of the tool bearing is arranged radially inside the stator of the rotary drive motor. In the radial direction of the drive spindle the rotary/lifting drive according to the invention is consequently comparatively small. The resulting dimensions of the rotary/lifting drive in the axial direction of the drive spindle may also be relatively small.  
         [0005]     In another possible embodiment, a compact construction of the complete machine may be achieved by minimizing the number of drive motors needed for the stroke movement and the rotary adjustment of the tool bearing. In this embodiment, a single rotary/lifting drive motor is provided, which serves both for movement of the tool bearing in the direction of the lifting axis and for rotary adjustment of the tool bearing about the lifting axis. This dual function of the rotary/lifting drive motor is facilitated by a controllable switching arrangement. This arrangement allows a driving element for the drive spindle to be connected to the rotary/lifting drive motor or to be disconnected from the rotary/lifting drive motor. In the one case, the rotary/lifting drive motor drives the driving element including the drive spindle about the spindle axis, which causes a rotary adjustment of the tool bearing about the lifting axis. If the driving element for the drive spindle and the rotary/lifting drive motor are disconnected from one another in respect of drive, then the rotary/lifting drive motor drives merely the lifting spindle nut. This results in the drive spindle being displaced in the direction of the spindle axis causing the tool bearing to be moved in the direction of the lifting axis.  
         [0006]     Further, in some other possible embodiments, the rotary movement of the drive spindle is accompanied by a corresponding rotary movement of the lifting spindle nut disposed on the drive spindle. As such, rotary adjustment of the tool bearing can be performed without a relative rotary movement of the lifting spindle nut and drive spindle to avoid a movement of the tool bearing along the lifting axis.  
         [0007]     In still another possible embodiment, there is provided a coupling slide between the motor-side lifting spindle nut and the driving element for the drive spindle to facilitate the connection or disconnection of the rotary/lifting drive motor and the driving element for the drive spindle. For example, in one embodiment, a force-fit connection may be employed. In another embodiment, an interlocking connection may be employed.  
         [0008]     In yet another embodiment a rotation prevention system is provided for the drive spindle. More specifically, on disconnection of the driving element from the rotary/lifting drive motor, the rotation prevention system prevents rotation of the drive spindle about the spindle axis. The drive connection of the lifting spindle nut and rotary/lifting drive motor consequently affects an exclusively axial movement of the drive spindle, and, hence, a lifting movement of the tool bearing without associated rotary adjustment movement. For example, in one embodiment, the rotation prevention system of the drive spindle may include an anti-rotation slide that can be either fixed against rotation about the spindle axis or can be released for such a rotation.  
         [0009]     In still another possible embodiment, a coupling/anti-rotation slide undertakes both the connection or disconnection in respect of drive of the rotary/lifting drive motor and the driving element for the drive spindle, as well as the establishment or termination of rotary protection of the drive spindle. In still another embodiment, a torque motor may be employed as either the lifting drive motor and/or the rotary drive motor. As will be appreciated, this type of motor enables even high torques to be transferred without interposed gearing as such embodiments employing a torque motor may be compact.  
         [0010]     In yet another embodiment, there is provided, a punching machine including a tool bearing, a drive spindle coupled to the tool bearing, and a drive system configured to move the tool bearing axially along a lifting axis and to rotate the tool bearing about the lifting axis, the drive system including a motor system comprising a stator and a rotor internally coupled to the stator and a spindle nut coupled to the rotor and cooperating with the drive spindle, wherein the spindle nut is at least partially disposed within the stator.  
         [0011]     In still another configuration, there is provided a punching machine including a tool bearing, a drive system configured to move the tool bearing axially along a lifting axis and to rotate the tool bearing about the lifting axis, the drive system including a motor system comprising a stator and a rotor internally coupled to the stator and a drive element coupled to the rotor and configured to transmit rotary movement from the rotor to the tool bearing, wherein the torque drive element is at least partially disposed within the stator.  
         [0012]     In still another configuration, there is provided a punching machine including a tool bearing, a drive system configured to move the tool bearing axially along a lifting axis and to rotate the tool bearing about the lifting axis, the drive system including a motor comprising a first stator and a first rotor internally coupled to the first stator and a driving element engageable with the motor, wherein the driving element is configured to prevent rotation of the tool bearing about the lifting axis when the driving element is disengaged with the motor, such that the tool bearing is configured to move axially along the lifting axis without rotation when the driving element is disengaged with the motor, and wherein the driving element is configured to rotate the tool bearing about the lifting axis when the driving element is engaged with the motor. 
     
    
     DESCRIPTION OF DRAWINGS  
       [0013]     The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the invention will be apparent from the description and drawings, and from the claims.  
         [0014]      FIG. 1  shows a partial sectional side-view of a punching machine having a first construction of an electric rotary/lifting drive for a punch upper die;  
         [0015]      FIG. 2  shows the rotary/lifting drive of  FIG. 1  in a first operating state;  
         [0016]      FIG. 3  shows the rotary/lifting drive of  FIGS. 1 and 2  in a second operating state;  
         [0017]      FIG. 4  shows a cross-sectional view of a section plane from  FIG. 2  running perpendicular to the drawing plane and along the line IV-IV;  
         [0018]      FIG. 5  shows a cross-sectional view of a section plane from  FIG. 2  perpendicular to the drawing plane and along the line V-V;  
         [0019]      FIG. 6  shows another embodiment of the electric rotary/lifting drive for a punch upper die, and  
         [0020]      FIG. 7  shows yet another embodiment of an electric rotary/lifting drive for a punch upper die of a punching machine.  
         [0021]     Like reference symbols in the various drawings indicate like elements. 
     
    
     DETAILED DESCRIPTION  
       [0022]     As shown in  FIG. 1 , a punching machine  1  has a C-shaped machine frame  2  with an upper frame member  3  and a lower frame member  4 . An electric rotary/lifting drive  5  for a punching tool in the form of a punch  6  and for a tool bearing  7  equipped with the punch  6 , is mounted at the free end of the upper frame member  3 . By means of the rotary/lifting drive  5 , the tool bearing  7  is movable in a straight line jointly with the punch  6  in the direction of a lifting axis  8  and is adjustable by rotation in the direction of a double arrow  9  about the lifting axis  8 . Movements in the direction of the lifting axis  8  may be performed by the tool bearing  7  and the punch  6  during the working strokes for processing workpieces and during return strokes following the working strokes. Rotary adjustment of the tool bearing  7  and the punch  6  is performed to change the rotated position of the punch  6  relative to the lifting axis  8 .  
         [0023]     When machining a workpiece, (e.g., when punching sheets), the punch  6  cooperates with a punching lower tool (not shown) in the form of a die. In one embodiment, the punching lower tool may be integrated into a workpiece table  10 , which in its turn mounted on the lower frame member  4  of the punching machine  1 . The relative movements of the sheet that are required during machining of the workpiece relative to the punch  6  and the die are performed by a coordinate guide  12  housed in a gap area  11  of the machine frame  2 .  
         [0024]     As can be inferred in detail from FIGS.  2  to  5 , the rotary/lifting drive  5  may include a drive housing  13  that has an electric rotary/lifting drive motor  14  of which the direction of rotation may be reversible. In one embodiment, the rotary/lifting drive motor  14  is a torque motor with a stator  15  fixed to the housing and with a rotor  16  rotating inside the stator  15  about the lifting axis  8 . The rotor  16  of the rotary/lifting drive motor  14  may be directly and hence gearlessly connected to a lifting spindle nut  17 , which sits on a drive spindle  18 .  
         [0025]     A spindle axis  19  of the drive spindle  18  may coincide with the lifting axis  8 . In the axial direction, the lifting spindle nut  17  and the stator  15  of the rotary/lifting drive motor  14  are arranged mutually overlapping with its axial end facing towards the tool bearing  7 . The lifting spindle nut  17  has a flange  20  at its axial end facing towards the tool bearing  7 . A rolling-contact bearing  21  may be provided for rotary mounting of the lifting spindle nut  17  on the drive housing  13 . By means of a first sensor arrangement  22  the direction of rotation and the angle of rotation of the lifting spindle nut  17  rotating about the lifting axis  8  (i.e. the spindle axis  19 ) may be detected. Jointly with the drive spindle  18 , the lifting spindle nut  17  forms a spindle transmission  23 , which in the embodiment illustrated is constructed as a ball screw transmission. Adjoining the drive spindle  18  towards the tool bearing  7 , there is an axial extension  24  that is integral with the drive spindle  18 . The axial extension  24  may be a circular cylindrical body from which radial fins  25  may project for part of the length of the axial extension  24 . The radial fins  25  may have a substantially rectangular cross-section, as shown in  FIG. 5  and may be received in axial guide grooves  26  of a driving element  27 .  
         [0026]     The driving element  27  surrounds the axial extension  24  and the drive spindle  18  concentrically. Its axial guide grooves  26  form, in cooperation with the radial fins  25  of the axial extension  24 , an axial guide  28  for the axial extension  24  and the drive spindle  18  constructed in one piece therewith. A rolling-contact bearing  29  may be responsible for the rotary mounting of the driving element  27  and the axial extension  24  and the drive spindle  18  on the drive housing  13 . A second sensor arrangement  30  serves to detect the rotated position of the axial extension  24  and of the tool bearing  7  provided thereon and of the punch  6  relative to the lifting axis  8 .  
         [0027]     The driving element  27  can either be connected in respect of drive to the rotary/lifting drive motor  14  or can be disconnected in respect of drive from the rotary/lifting drive motor  14  by means of a controllable switching arrangement  31 . For that purpose, the controllable switching arrangement  31  may include a coupling/anti-rotation, slide  32 , which is slidably guided in the axial direction on the outside of the driving element  27 . Around the lifting axis  8 , the coupling/anti-rotation slide  32  is supported on the driving element  27  secured against rotation by splines. A plurality of actuating slides  33 , which are movably guided on the drive housing  13  in the direction of the lifting axis  8  and have a common pneumatic drive, serves for axial displacement of the coupling/anti-rotation slide  32 .  
         [0028]     The coupling/anti-rotation slide  32  engages with the free end of a flange  34  in the actuating slides  33 . A radial flange face  35  of the flange  34  on the coupling/anti-rotation slide  32  lies opposite a radial flange face  36  on the flange  20  of the lifting spindle nut  17 . On its side opposite from the radial flange face  35 , the flange  34  of the coupling/anti-rotation slide  32  is provided with a further radial flange face  37 , which is associated with a bearing surface  38  on the drive housing  13 .  
         [0029]      FIG. 2  shows the electric rotary/lifting drive  5  in the operating state associated with workpiece punching. Accordingly, the lifting spindle nut  17  mounted rotatably and axially fixed on the drive housing  13  is rotated in the direction of rotation concerned about the lifting axis  8 , i.e. the spindle axis  19 . The coupling/anti-rotation slide  32  of the controllable switching arrangement  31  is then displaced into its lower final position by means of the actuating slides  33 . The driving element  27  is consequently disconnected in respect of drive from the rotary/lifting drive motor  14 .  
         [0030]     Further, during operation, the radial flange face  37  on the coupling/anti-rotation slide  32  is supported on the bearing surface  38  of the drive housing  13 . By virtue of the normal force acting on the radial flange face  37  of the coupling/anti-rotation slide  32  and the bearing surface  38  of the drive housing  13 , the coupling/anti-rotation slide  32  is fixed on the drive housing  13  against rotation about the lifting axis  8 . By means of the coupling/anti-rotation slide  32 , the driving element  27  and the axial extension  24  supported thereon locked against rotation and the drive spindle  18  is constructed in one piece with the extension  24  secured against rotation about the lifting axis  8 . Accordingly, the coupling/anti-rotation slide  32  in cooperation with the driving element  27  and the drive housing  13  forms a rotation preventing system  39  for the drive spindle  18  with the drive housing  13  serving as an abutment for the driving element.  
         [0031]     The rotation prevention system  39  prevents the drive spindle  18  from being carried with the lifting spindle nut  17  rotating about the lifting axis  8 . Owing to the rotation of the lifting spindle nut  17  relative to the drive spindle  18 , the drive spindle  18  is displaced in the direction of the lifting axis  8  jointly with the axial extension  24 . The tool bearing  7  provided thereon and the punch  6  is held in the tool bearing  7 . Depending on the direction of rotation of the lifting spindle nut  17 , the tool bearing  7  and the punch  6  are lowered with a working stroke towards the workpiece to be machined or alternatively following a working stroke are retracted with respect to the workpiece with a reverse stroke.  
         [0032]      FIG. 3  illustrates the embodiment of  FIG. 2  when the rotated position of the tool bearing  7  and the punch  6  relative to the lifting axis  8  is to be changed. In this case, the driving element  27  and the rotary/lifting drive motor  14  are connected to one another in respect of drive by way of the coupling/anti-rotation slide  32  of the controllable switching arrangement  31 . For that purpose, the coupling/anti-rotation slide  32  is displaced by means of the actuating slides  33  into an axial position. When it has assumed that position, it is pressed with its radial flange face  35  onto the radial flange face  36  of the lifting spindle nut  17 . A force-fit connection is consequently produced between the lifting spindle nut  17  and the coupling/anti-rotation slide  32 . By virtue of this force-fit connection, the coupling/anti-rotation slide  32 , the driving element  27  as well as the axial extension  24 , and the drive spindle  18  move jointly with the lifting spindle nut  17  in the direction of rotation thereof. In the process, there is no relative rotary movement between lifting spindle nut  17  and drive spindle  18 . The drive spindle  18 , the axial extension  24  and the tool bearing  7  with punch  6  provided thereon perform exclusively a rotary movement about the lifting axis  8 .  
         [0033]     In one embodiment, all the functions of the electric rotary/lifting drive  5  are numerically controlled. For example, the first sensor arrangement  22  and the second sensor arrangement  30  may be part of the numeric control system. The first sensor arrangement  22  may serve here for controlled execution of the working strokes and the reverse strokes of the punch  6  in the direction of the lifting axis  8 . The second sensor arrangement  30  may serves for control of the rotary adjustment of the punch  6  about the lifting axis  8 . In one embodiment, the rotary adjustment of the punch  6  encompasses a corresponding rotary adjustment of the die co-operating with the punch  6 .  
         [0034]      FIG. 6  illustrates another embodiment having an electric rotary/lifting drive  55  with two separate drive motors. The electric rotary/lifting drive  55  can be used on the punching machine  1  in place of the electric rotary/lifting drive  5 . The electric rotary/lifting drive  55  comprises a rotary drive motor  64   a  and a lifting drive motor  64   b.  In one embodiment, both motors may be torque motors. The rotary drive motor  64   a  has a stator  65   a  and a rotor  66   a,  which is directly connected to a driving element  77 . During operation, the rotary drive motor  64   a  rotates jointly with the driving element  77  about the lifting axis  8  of the rotary/lifting drive  55 .  
         [0035]     The driving element  77  supports an axial extension  74  that may be formed in one piece with a drive spindle  68 . Unlike the axial extension  24  according to FIGS.  2  to  5 , in one embodiment, the axial extension  74  includes a hollow cylinder. The axial extension  74  may engage with radial fins  75  in axial guide grooves  76  on the driving element  77 . Together, the radial fins  75  on the axial extension  74  and the axial guide grooves  76  on the driving element  77  form an axial guide  78  for the axial extension  74  and the drive spindle  68  formed in one piece therewith.  
         [0036]     A lifting spindle nut  67  is located on the drive spindle  68 . The lifting spindle nut  67  is rotatable about the lifting axis  8  and (may be mounted) in the direction of the lifting axis. In one embodiment, the lifting spindle nut  67  is connected to a rotor  66   b  of the lifting drive motor  64   b  without interposed gearing. Associated with the rotor  66   b  is a stator  65   b  of the lifting drive motor  64   b.  A spindle axis  19  of the drive spindle  68  coincides with the lifting axis  8 . Unlike the drive spindle  18  according to FIGS.  2  to  5 , the drive spindle  68  may take the form of a hollow spindle.  
         [0037]     The tool bearing  7  with the punch  6  may also be arranged on a ram  81 , which is fixed in the axial seat of the drive spindle  68 . The lifting spindle nut  67  and the drive spindle  68  form a spindle transmission  73 , which like the spindle transmission  23  (FIGS.  2  to  5 ), may be in the form of a ball screw transmission. In the direction of the lifting axis  8  and in the direction of the spindle axis  19  respectively, the lifting spindle nut  67  and the stator  65   b  of the lifting drive motor  64   b  are arranged mutually overlapping. Furthermore, the driving element  77  and the stator  65   a  of the rotary drive motor  64   a  may also be overlapping.  
         [0038]     For punching workpieces, the lifting drive motor  64   b  may be operated. The lifting spindle nut  67  rotating jointly with the rotor  66   b  of the lifting drive motor  64   b  drives the drive spindle  68  in the direction of the lifting axis  8 . Depending on the direction of rotation of the lifting spindle nut  67 , the drive spindle  68  (and with it the tool bearing  7  plus the punch  6 ) is lowered towards the workpiece to be machined or is retracted with respect to the machined workpiece. The rotary drive motor  64   a  is off during punching operation of the electric rotary/lifting drive  55 . When the rotary drive motor  64   a  is off, the rotor  66   a  is blocked in the direction of rotation from rotation about the lifting axis  8 . The same applies to the driving element  77 , which is supported with positive locking on the rotor  66   a.  The off-state rotary drive motor  64   a  jointly with the driving element  77  prevents rotation of the drive spindle  68  moving in the axial direction.  
         [0039]     To change the rotary adjustment of the tool bearing  7  and of the punch  6  relative to the lifting axis  8 , the rotary drive motor  64   a  and the lifting drive motor  64   b  are operated in the same direction of rotation and at the same speed of rotation. The rotor  66   a  of the rotary drive motor  64   a  in the process entrains the axial extension  74 , and by way of this the drive spindle  68 , and the lifting drive motor  64   b  entrains the lifting spindle nut  67  in the relevant direction of rotation through the desired angle of rotation. In this manner, the rotary adjustment of the tool bearing  7  and the punch  6  is changed, without a relative rotary movement of lifting spindle nut  67  and drive spindle  68  and, thus, an associated axial displacement of the drive spindle  68 .  
         [0040]     The functions of the electric rotary/lifting drive  55  may also be numerically controlled. Components of the numeric control include, amongst other things, sensors (not shown nor explained in detail) for detecting speed of rotation, rotated angle, and direction of rotation of the lifting spindle nut  67  and the drive spindle  68 .  
         [0041]      FIG. 7  shows yet another embodiment of an electric rotary/lifting drive  85  with drive motors  94   a,    94   b  in the form of torque motors. The drive motor  94   a  has a stator  95   a  and a rotor  96   a;  the drive motor  94   b  has a stator  95   b  and a rotor  96   b.  The rotor  96   a  is directly connected to a lifting spindle nut  97   a;  the rotor  96   b  is directly connected to a lifting spindle nut  97   b.  The lifting spindle nut  97   a  sits on a drive spindle  98   a;  the lifting spindle nut  97   b  sits on a drive spindle  98   b.  The lifting spindle nuts  97   a,    97   b  and the associated motors  95   a,    95   b  of the drive motors  94   a,    94   b  are arranged mutually axially overlapping.  
         [0042]     Both drive spindles  98   a,    98   b  may be in the form of hollow spindles. On their inside, the drive spindles  98   a,    98   b  receive a ram  111 , at the workpiece-side end of which the tool bearing  7  with the punch  6  is provided. The drive spindles  98   a,    98   b  are connected to the ram  111  to form a single structural unit. The lifting axis  8  of the rotary/lifting drive  85  coincides with a common spindle axis  19  of the drive spindles  98   a,    98   b.  Together with the drive spindle  98   a,  the lifting spindle nut  97   a  may form a spindle transmission  103   a,  and together with the drive spindle  98   b,  the lifting spindle nut  97   b  may form a spindle transmission  103   b.  In one embodiment, the spindle transmissions  103   a,    103   b  have oppositely directed threads, but are otherwise of identical construction.  
         [0043]     For punching workpieces, the two drive motors  94   a,    94   b  are operated at the same speed but in opposite directions. As a result, the drive spindles  98   a,    98   b  and the tool bearing  7  and the punch  6  are displaced in the direction of the lifting axis  8 . By virtue of the oppositely directed motor drive, the lifting spindle nut  97   a  and the drive motor  94   a  prevent rotation of the drive spindle  98   b.  The lifting spindle nut  97   b  and the drive motor  94   b  prevent rotation for the drive spindle  98   a.    
         [0044]     For rotary adjustment of the tool bearing  7  and the punch  6  about the lifting axis  8  and the spindle axis  19  respectively, the drive motors  94   a,    94   b  are operated at corresponding speed and with identical direction of rotation. This results in a joint rotary movement of the lifting spindle nut  97   a  and the drive spindle  98   a  and of the lifting spindle nut  97   b  and the drive spindle  98   b.  There is little or no relative rotary movement between the lifting spindle nut  97   a  and the drive spindle  98   a  or between the lifting spindle nut  97   b  and the drive spindle  98   b.  In this state, the lifting spindle nuts  97   a,    97   b  act as driving elements for the drive spindles  98   a,    98   b.  As such, depending on the mode of operation, the drive motors  94   a,    94   b  may form rotary drive motors or lifting drive motors. Additionally, an axial displacement of the drive spindles  98   a,    98   b  and of the tool bearing  7  with the punch  6  with simultaneous change in the rotated position relative to the lifting axis  8  is also possible. For example, in one embodiment, this effect may be achieved by operating the drive motors  94   a,    94   b  at different speeds.  
         [0045]     Additional description of one or more of the features described above may be provided in commonly assigned U.S. patent application Ser. No. ______ entitled SPINDLE DRIVE SUPPORT, filed Nov. 27, 2006 (Our Ref.: 15540- 100001), and/or commonly assigned U.S. patent application Ser. No. ______, entitled COUNTER-ROTATING SPINDLE TRANSMISSION, filed Nov. 27, 2006 (Our Ref.: 15540-101001). Both of these applications are hereby incorporated by reference.  
         [0046]     A number of embodiments of the invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. For example, in other embodiments other suitable motors or transmission types may be employed. Accordingly, other embodiments are within the scope of the following claims