Abstract:
The invention relates to a drive device for multiaxial transport of workpieces through successive machining stations of a machine tool, in particular of a multistage forming press, wherein the drive device comprises two gripper rails, wherein the two gripper rails are transversely displaceable independently of each other by a first transverse drive assigned to the first gripper rail and a second transverse drive assigned to the second gripper rail for the execution of a closing movement. The gripper rails are here vertically displaceable independently of each other for the execution of a lifting movement, and/or the gripper rails are longitudinally displaceable independently of each other for the execution of a transport movement.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of International Application No. PCT/EP2012/003428 filed Aug. 10, 2012, which designated the United States, and claims the benefit under 35 USC §119(a)-(d) of German Application No. 10 2011 118 216.4 filed Nov. 11, 2011, the entireties of which are incorporated herein by reference. 
     
    
     FIELD OF THE INVENTION 
       [0002]    The invention relates to a drive device for multiaxial transport of workpieces through successive machining stations of a machine tool. 
       BACKGROUND OF THE INVENTION 
       [0003]    A drive system for the closing movement of a multiaxial transport of workpieces in a transfer press is known from DE 199 14 652 C1. In this drive system, a dedicated drive with motion transfer means is assigned to the right-hand and left-hand gripper rail, so that the gripper rails are horizontally displaceable independently of each other. For the raising and lowering of the gripper rails, the drive system has a complex lifting mechanism, which extends almost over the entire width of the drive system and drives both gripper rails. Similarly, in a longitudinal movement in the direction of transport, the two gripper rails are jointly driven. 
       SUMMARY OF THE INVENTION 
       [0004]    The object of the invention is to propose a drive device for multiaxial transport of workpieces, which, despite simple structure, has increased flexibility with respect to the gripping, raising and onward transportation. 
         [0005]    In the drive device according to the invention, the gripper rails are vertically displaceable independently of each other for the execution of a lifting movement, and/or the gripper rails are longitudinally displaceable independently of each other for the execution of a transport movement. With a drive device of this type, it is possible, for example, to raise a workpiece slightly in the lifting movement initially with a gripper rail so as to be able with lower force expenditure to surmount the adhesion forces which the workpiece has to a bottom part of the press, for example. With a drive device of this type, it is possible, for example, to easily adjust a workpiece, in terms of its position, in the course of the transport movement, by displacing one gripper rail in relation to the other gripper rail by a greater path distance longitudinally in the direction of transport. The centerpiece of the invention is thus an increase in flexibility of the drive device, so that the latter, where necessary, is available for extended handling tasks. 
         [0006]    In addition, the invention provides to equip the drive device with a first vertical drive, assigned to the first gripper rail, and a second vertical drive, assigned to the second gripper rail, by which the gripper rails are vertically displaceable independently of each other for the execution of the lifting movement, wherein the first vertical drive comprises, in particular, a first parallelogram guide and wherein the second vertical drive comprises, in particular, a second parallelogram guide. Through the use of two vertical drives, an independent lifting movement is technically easily realizable, wherein a lifting movement can be realized with technically simple means via a parallelogram guide. 
         [0007]    The invention also provides to equip the drive device with a first longitudinal drive, assigned to the first gripper rail, and a second longitudinal drive, assigned to the second gripper rail, by which the gripper rails are longitudinally displaceable independently of each other for the execution of the transport movement, wherein the longitudinal drives comprise, in particular, respectively a first universal joint, a telescopic splined shaft, a second universal joint and a gear mechanism. Through the use of standardized components of this type, an independent transport movement is technically easily realizable. 
         [0008]    In addition, the invention provides that also the two transverse drives respectively comprise a parallelogram guide. As a result, the transport drives too are constructed in a cost-effective and technically simple manner. 
         [0009]    For the linkage of the vertical movement and the transverse movement, it is provided that the first vertical drive bears the first transverse drive and the second vertical drive bears the second transverse drive, or that the first transverse drive bears the first vertical drive and the second transverse drive bears the second vertical drive. A compact and simple construction, in which similar components can find multiple application, is hereby achieved. 
         [0010]    The invention also provides to equip the lower parallelogram guide with a lower bearing arm having two fixed pivot points, a connecting branch having two hinge points, and two parallel running connecting elements, wherein the first connecting element is articulately fastened to the pivot point and to the hinge point and wherein the second connecting element is articulately fastened to the pivot point and to the hinge point, just as the invention provides to equip the upper parallelogram guide with a lower bearing arm having two fixed pivot points, a connecting branch having two hinge points, and two parallel running connecting elements, wherein the first connecting element is articulately fastened to the pivot point and to the hinge point and wherein the second connecting element is articulately fastened to the pivot point and to the hinge point. A compact and simple structure, in which similar components can find multiple application, is likewise hereby achieved. 
         [0011]    In addition, it is provided according to the invention to configure the connecting branch of the lower parallelogram guide as a coupling lever, wherein the fixed pivot points of the upper parallelogram guide are configured on the coupling lever, wherein a first lever arm of the coupling lever forms the connecting branch of the lower parallelogram guide, wherein a second lever arm of the coupling lever forms the lower bearing arm of the upper parallelogram guide, and wherein, in particular, one of the hinge points of the lower parallelogram guide and one of the pivot points of the upper parallelogram guide lie on a common rotational axis. Through such a linkage of the lower parallelogram guide and the upper parallelogram guide, a particularly compact structure of the drive device is achieved. 
         [0012]    The invention also provides to design the gripper rail such that it is displaceable relative to a gripper rail guide, wherein the connecting branch of the upper parallelogram guide is connected, in particular, to the gripper rail guide or is formed, in particular, by the gripper rail guide. A compact structure of the drive device is also hereby achieved. 
         [0013]    The invention also provides to form the drive device substantially by a first drive unit and a second drive unit, wherein the first drive unit comprises the transverse drive, the vertical drive and the longitudinal drive of the first gripper rail and wherein the second drive unit comprises the transverse drive, the vertical drive and the longitudinal drive of the second gripper rail. A symmetrical, in particular mirror-symmetrical structure of the drive device is hereby ensured, so that a same component can find multiple application. 
         [0014]    According to the invention, it is provided to equip the transverse drive with a first motor, which is configured, in particular, as an electric motor, wherein this motor, in particular with its output shaft, actuates the parallelogram guide of the transverse drive, in particular in one of its pivot points, and to equip the vertical drive with a second motor, which is configured, in particular, as an electric motor, wherein this motor, in particular with its output shaft, actuates the parallelogram guide of the vertical drive, in particular in one of its pivot points. Through this type of direct connection of the motors to the parallelogram guides, a compact structure is ensured. 
         [0015]    In addition, the invention provides to equip the longitudinal drive with a third motor, which is configured, in particular, as an electric motor, wherein the gripper rail is displaceable, in particular relative to the gripper rail guide, by the third motor in the longitudinal direction. As a result, a compact and simple structure is likewise achieved. 
         [0016]    According to the invention, it is additionally provided to connect the third motor fixedly to a first beam of the drive device, wherein an output shaft of the first motor drives via the first universal joint the telescopic splined shaft, and via the second universal joint the gripper rail, with the interposition of the gear mechanism. As a result of such a structure, the moved masses are kept small and high accelerations can be realized in a simple manner with small motor power. 
         [0017]    Finally, the invention provides to displace the two drive units with the respectively assigned gripper rails relative to each other in the transverse direction, by at least one further transverse drive, for the conductance of a basic adjustment. Such an arrangement makes it possible to adjust the distance between the two drive units, and thus also between the two gripper rails, so that large adjustment ranges with regard to the distance apart of the gripper rails can be realized, even if the transverse drive is dimensioned comparatively small. 
         [0018]    Within the meaning of the invention, a motor should be understood to embrace both an electric motor and a hydraulically or pneumatically working cylinder. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    Further details of the invention are described in the drawing on the basis of schematically represented illustrative embodiments, wherein: 
           [0020]      FIG. 1  shows a first drive unit of a drive device according to the invention in a first setting; 
           [0021]      FIG. 2  shows the first drive unit, shown in  FIG. 1 , in a second setting; 
           [0022]      FIG. 3  shows the first drive unit, known from  FIGS. 1 and 2 , together with a second drive unit constructed in mirror symmetry, wherein a machining station of a forming press, through which a workpiece is transported by the drive device, is additionally shown; 
           [0023]      FIG. 4  shows, in analogy to  FIG. 3 , the structural design of the two drive units of a drive device according to the invention; and 
           [0024]      FIGS. 5   a - 5   c  show three side views or partially sectioned side views of the drive device shown in  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0025]    In  FIG. 1  is shown, in schematic view, a first drive unit  1  of a drive device  2 . The first drive unit  1  comprises a first transverse drive TVA 1 , a first vertical drive VKA 1  and a first longitudinal drive LTA 1 . These drives TVA 1 , VKA 1  and LTA 1  are disposed on a beam T 1 . The first drive unit  1  additionally comprises a further transverse drive TVA 3 , which is fixedly connected to a base surface  3  and by which the beam T 1  is displaceable on the base surface  3  in the x or x′ direction. The drive unit  1  comprises a first gripper rail  4 , which, for the onward transport of workpieces in the arrow direction z or z′, is displaceable by the first longitudinal drive LTA 1  in a gripper rail guide  5 . The gripper rail  4  is displaceable by the first transverse drive TVA 1  to the right or left in the x or x′ direction, and the gripper rail  4  is displaceable by the vertical drive VKA 1  upward or downward in the y or y′ direction. The first vertical guide VKA 1  here comprises a first, lower parallelogram guide  6   a,  and the first transverse guide TVA 1  comprises a second, upper parallelogram guide  7   a.  The first, lower parallelogram guide  6   a  comprises a lower bearing arm  8  having two fixed pivot points A, B, a connecting branch  9  having two hinge points C, D, and two parallel running connecting elements  10 ,  11 . The first connecting element  10  here connects the pivot point A to the hinge point C, and the second connecting element  11  connects the pivot point B to the hinge point D. The first vertical guide VKA 1  further comprises a motor M 1 , which is flange-connected to the bearing arm  8 , is configured as an electric motor E 1  and, with its drive shaft  12 , rotates the connecting element  10  about the pivot point A in order to raise the gripper rail  4  from a y position Y 1  (see  FIG. 1 ) to a y position Y 2  (see  FIG. 2 ). To this end, the connecting element  10  is rotated out of its horizontal setting shown in  FIG. 1 , through an angle α, into a setting shown in  FIG. 2 . The connecting branch  9 , which is configured as a coupling lever  13  and comprises a first lever arm  13   a  and a second lever arm  13   b,  is raised by the parallelogram guide  6   a,  wherein the first lever arm  13   a  is formed by the connecting branch  9  and wherein the second lever arm  13   b  forms a lower bearing arm  14  of the second, upper parallelogram guide  7   a.  As a result of the one-piece construction of the connecting branch  9  of the first vertical drive VKA 1  and of the lower bearing arm  14  of the first transverse drive TVA 1 , the first transverse drive TVA 1  is raised by the vertical drive VKA 1 , so that the transverse drive TVA 1  disposed between the gripper rail  4  and the vertical drive VKA 1  joins in all lifting and lowering movements of the vertical drive VKA 1 . The transverse drive TVA 1  comprises, in addition to the aforementioned lower bearing arm  14 , a connecting branch  15  and two connecting elements  16 ,  17 , pivot points E, F and hinge points G, H. The two connecting elements  16 ,  17  here connect the bearing arm  14  and the connecting branch  15  at the points E and G, as well as F and H. The first transverse drive TVA 1  further comprises a motor M 2 , which is flange-connected to the bearing arm  14 , is configured as an electric motor E 2 , and, with its drive shaft  18 , rotates the connecting element  16  about the pivot point E in order to shift the gripper rail  4  from an x position X 1  (see  FIG. 1 ) to an x position X 2  (see  FIG. 2 ) in the arrow direction x. To this end, the connecting element  16  is rotated out of its vertical setting shown in  FIG. 1 , through an angle β, into a setting shown in  FIG. 2 . The connecting branch  15  is formed by the gripper rail guide  5 . The first longitudinal drive LTA 1  comprises a motor M 3 , which is configured as an electric motor E 3  and, via its drive shaft  19  and a universal joint  20  connected thereto, drives a telescopic splined shaft  21 , wherein the telescopic splined shaft  21 , via a further universal joint  22 , drives a pinion  23 , which is mounted in the gripper rail guide  5  and, together with the gripper rail  4  configured as a toothed rack  24 , forms a gear mechanism  25 . By a rotation of the pinion  23  acting on the toothed rack  24 , the gripper rail  4  is displaceable in the z or z′ direction. The motor M 3  is fixedly disposed on the beam T 1 . The telescopic splined shaft  21  and the two universal joints  20  and  22  enable the toothed rack  24  configured on the gripper rail  4  to be drivable by the first longitudinal drive LTA 1  irrespective of the x position and y position of the gripper rail guide  5  or gripper rail  4 . When comparing  FIGS. 1 and 2 , it can be seen how the first longitudinal drive LTA 1  drives the gripper rail  4  in its position X 1 , Y 1  and in its position X 2 , Y 2 . 
         [0026]    As already mentioned,  FIG. 2  shows the first drive unit  1  of the drive device  2  in that position X 2 , Y 2  of its gripper rail  4  which, starting from the position X 1 , Y 1  shown in  FIG. 1 , has been reached by a lifting movement of the first vertical drive VKA 1  and a transverse movement of the first transverse drive TVA 1 . The first longitudinal drive LTA 1  here passively follows the predefined position, in that the angular settings of the universal joints  20 ,  22  and the length of the telescopic splined shaft  21  are adapted or positionally adjusted to the setting of the gripper rail guide  5  or of the gripper rail  4 . The drive device  2  also comprises an electronic control device  26 , shown in  FIG. 2 , which controls or regulates the motors M 1  and M 2  of the first vertical drive VKA 1  and of the first transverse drive TVA 1  such that the desired x position and y position, despite a superimposition of the two drives, are reached precisely and directly. At variance with the representation of  FIG. 1 ,  FIG. 2  shows, alternatively to the third transverse drive TVA 3 , which moves the beam T 1 , a fifth transverse drive TVA 5 , to which both the described first drive unit  1  and a hitherto unshown second drive unit  27  are connected, of which latter, in  FIG. 2 , only a beam T 27  is rudimentarily shown. The fifth transverse drive TVA 5  comprises a spindle  28 , by whose rotation a distance a between the first drive unit  1  and the second drive unit  27  can be increased or reduced, wherein the spindle  28  is guided in the beams T 1  and T 27  in spindle nuts (not represented). 
         [0027]    In  FIG. 3 , the drive device  2  according to the invention is shown in full. This substantially comprises the first drive unit  1 , shown in  FIGS. 1 and 2 , and the second drive unit  27 , already shown rudimentarily in  FIG. 2 , wherein the drive unit  27  is configured, in relation to a mirror plane SE running perpendicularly into the drawing plane, substantially mirror-symmetrically to the first drive unit  1  and comprises a second transverse drive TVA 2 , a second vertical drive VKA 2 , and a second longitudinal drive LTA 2 . The second vertical drive VKA 2  here comprises a further, lower parallelogram guide  6   b , and the second vertical drive VKA 2  comprises a further, upper parallelogram guide  7   b.  In accordance with the embodiment shown in  FIG. 1 , the second drive unit  27  comprises a fourth transverse drive TVA 4 , which is connected to the beam T 27 .  FIG. 3  shows, in addition to the drive device  2  having the drive units  1  and  27 , a machining station  29  of a multistage forming press  30 , in which precisely one workpiece  31  is transported by the drive device  2  with its gripper rails  4  and  32 . The machining station  29  comprises a bottom tool  33  and a top tool  34 . In a step following on from the representation, the workpiece  33  is deposited by the drive device  2  on the bottom tool  33  and, in a further step, is deep-drawn by the top tool  34 . 
         [0028]    In  FIG. 4 , in analogy to  FIG. 3 , the structural design construction of an inventive drive device  2  having two drive units  1 ,  27  is shown. The two drive units  1 ,  27  are here represented in a middle region MB of  FIG. 4  in a closely converged setting, and in outer regions AB 1  and AB 2  are shown in partial representation in a widely diverged setting. In the middle region MB of  FIG. 4 , a first and a second transverse drive TVA 1 , TVA 2 , a first and a second vertical drive VKA 1 , VKA 2 , and a first and a second longitudinal drive LTA 1 , LTA 2 , as well as motors M 1  to M 6 , are discernible. In addition, gripper rails  4 ,  32  of the two drive units  1 ,  27  are shown by way of example in a basic setting G 1 , G 27 , a raised setting V 1 , V 27 , and a laterally displaced setting T 1 , T 27 . 
         [0029]    In  FIGS. 5   a  to  5   c , side views or partially sectioned side views of the drive device  2  represented in  FIG. 4  are shown. 
         [0030]    The invention is not limited to represented or described illustrative embodiments, but rather embraces refinements of the invention within the scope of the patent claims. 
       REFERENCE SYMBOL LIST 
       [0000]    
       
           1  first drive unit of  2   
           2  drive device 
           3  base surface 
           4  first gripper rail 
           5  gripper rail guide 
           6   a  first, lower parallelogram guide 
           6   b  further, lower parallelogram guide 
           7   a  further, upper parallelogram guide 
           7   b  further, upper parallelogram guide 
           8  lower bearing arm of  6   a    
           9  connecting branch of  6   a    
           10  connecting element of  6   a    
           11  connecting element of  6   a    
           12  drive shaft of E 1   
           13  coupling lever 
           13   a  first lever arm of  13   
           13   b  second lever arm of  13   
           14  lower bearing arm of  7   a    
           15  connecting branch of  7   a    
           16  connecting element of  7   a    
           17  connecting element of  7   a    
           18  drive shaft of E 2   
           19  drive shaft of LTA 1   
           20  universal joint of HZA  1   
           21  telescopic splined shaft of LTA 1   
           22  universal joint of LTA 1   
           23  pinion of LTA 1   
           24  toothed rack 
           25  gear mechanism consisting of  23  and  24   
           26  electronic control unit 
           27  second drive unit of  2   
           28  spindle of TVA 5   
           29  machining station 
           30  multistage forming press 
           31  workpiece 
           32  second gripper rail 
           33  bottom tool 
           34  top tool 
         A, B pivot point of  6   a    
         C, D hinge point of  6   a    
         E, F pivot point of  7   a    
         G, H hinge point of  7   a    
         a distance between T 1  and T 27   
         E 1 -E 3  electric motor 
         G 1 , G 27  basic setting G 1 , G 27  of  4  and  32   
         LTA 1  first longitudinal drive 
         LTA 2  second longitudinal drive 
         M 1  motor of VKA 1   
         M 2  motor of TVA 1   
         M 3  motor of LTA 1   
         M 4  motor of VKA 2   
         M 5  motor of TVA 2   
         M 6  motor of LTA 2   
         MB middle region of  FIG. 4   
         AB 1 , AB 2  outer region of  FIG. 4   
         SE mirror plane 
         T 1  beam of  1   
         T 27  beam of  27   
         TVA 1  first transverse drive 
         TVA 2  second transverse drive 
         TVA 3  third transverse drive 
         TVA 4  fourth transverse drive 
         TVA 5  fifth transverse drive 
         T 1 , T 27  laterally displaced setting of  4  and  32   
         VKA 1  first vertical drive 
         VKA 2  second vertical drive 
         V 1 , V 27  raised setting of  4  and  32   
         X 1 , X 2  x position 
         x, x′ direction 
         Y 1 , Y 2  y position 
         y, y′ direction 
         z, z′ direction 
         α,  62  angle