Abstract:
In a transfer system, transport beams are displaced in three types of motions, i.e. toward each other, along a longitudinal extension thereof for advancement, and up and down. Two of these types of motions are triggered by a double-function motor. Such a double-function motor includes a shaft, which simultaneously rotates and displaces back and forth in linear fashion along the longitudinal extension thereof.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is the US National Stage of International Application No. PCT/EP2008/052198 filed Feb. 22, 2008, and claims the benefit thereof. The International Application claims the benefits of German Patent Application No. 10 2007 009 747.8 DE filed Feb. 28, 2007; both of the applications are incorporated by reference herein in their entirety. 
     
    
     FIELD OF INVENTION 
       [0002]    The invention relates to a transfer system. Such a transfer system, frequently also known for short as a transfer, is provided in conjunction with an arrangement of multiple presses. The transfer system has the task of transporting one workpiece from one tool to the next within a press. 
         [0003]    The transfer system here has two transport beams extending in a straight line, which can also be designated as gripper rails. The transport beams are parallel to each other. In a first type of motion they are too-free-moving to clamp a workpiece in position. In a second type of motion they can be moved along their longitudinal extension, in order to transport the fixedly clamped workpiece. As a rule, the longitudinal movement is vertically relative to the clamping movement. In a third type of motion, the transport beams can be lifted, in order to raise the fixedly clamped workpiece, which is in particular sensible within a press. The lift movement generally takes place in a direction which is vertical relative to the two other movement directions. 
       BACKGROUND OF INVENTION 
       [0004]    Transfer systems of the type cited are for example described in detail in the book: Schuler, Handbuch der Umformtechnik, Schuler AG, Springer Verlag, Heidelberg, 1996, see in particular pages 230 to 242. 
         [0005]    JP-A-2005014071 discloses a transfer system in which a motor drives a toothed wheel, by means of which a lifting and at the same time a lateral movement of a plate is performed. 
         [0006]      FIG. 1  shows a three-dimensional view of a transfer system of the prior art, which is as a whole designated  10 . The transfer system  10  is intended to transport workpieces between the tools of a press, which are not shown in the figure, and may be between a few meters and almost  100  m in length. To mount the transfer system  10  on the presses, an assembly structure  12  is arranged at one end of the transfer system, and an assembly structure  14  is arranged at the other end of the transfer system. At the heart of the transfer system are two transport beams  16 . The transport beams  16  extend over the entire length of the transfer system  10 . A movement of the transport beams  16  is effected by means of three different electric motors  18 . It would basically be sufficient if three electric motors  18  were arranged on one side of the transfer system, but in the present instance, three electric motors  18  are in each case arranged on each side of the transfer system. One of the electric motors  18  on each side is responsible for a relative movement of the transport beams  16  towards each other corresponding to the arrow  20 . By means of this relative movement  20 , the transport beams can clamp a workpiece in place between them. A second of the electric motors  18  is responsible for a translatory movement along the longitudinal extension of the transport beams  16 , see arrow  22 . A third of the electric motors  18  on each side of the transfer system  10  is responsible for a lifting movement, see arrow  24 . 
         [0007]    The need to provide an electric motor in each case for each type of motion (arrows  20 ,  22  or  24 ), where the number of electric motors must even be doubled so that an electric motor effects the movement on both sides according to the type of motion, is a costly factor. 
       SUMMARY OF INVENTION 
       [0008]    An object of the invention is thus to design a more compact transfer system. 
         [0009]    The object is achieved in that the transfer system comprises a motor which is coupled to the transport beams in such a way that it effects movements of the transport beams according to two different types of motion of the three types of motion. This takes the form of a double-function motor, and this replaces two motors in the embodiment according to the prior art. The transfer system is thereby more compact. 
         [0010]    A so-called combination drive can be used as a motor (cf. for example DE 10 2005 019 112 A1): such a motor has a (bar-type) shaft, which can simultaneously be rotated by the motor, and moved backwards and forwards in a linear manner along its longitudinal extension. 
         [0011]    The rotary movement can then be responsible for a first type of motion of the transport beams, and the linear movement of the shaft can be responsible for a second type of motion of the transport beams. 
         [0012]    It is basically not laid down for which type of motion the rotary movement of the motor and for which the translatory movement of the shaft of the motor can be responsible. 
         [0013]    It has however proved not to be advantageous if translatory movement of the shaft of the motor is responsible for the second type of motion, because workpieces clamped in position may need to be transported over lengthy distances, while on the other hand there are limits on the translatory movement of the shaft. 
         [0014]    The following four embodiments are therefore preferred: 
         [0015]    According to a first embodiment, the rotary movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the third type of motion and the translatory movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the first type of motion. 
         [0016]    In a second embodiment, the rotary movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the first type of motion and the translatory movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the third type of motion. 
         [0017]    In a third embodiment, the rotary movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the second type of motion and the translatory movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the first type of motion. 
         [0018]    In a fourth embodiment, the rotary movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the second type of motion and the translatory movement of the shaft of the motor is responsible for a movement of the transport beams corresponding to the third type of motion. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0019]    A preferred embodiment of the invention is described below, with reference to the drawing, wherein 
           [0020]      FIG. 1  shows a three-dimensional view of a transfer system according to the prior art and 
           [0021]      FIG. 2  shows a cross-sectional view of a transfer system according to the invention. 
       
    
    
     DETAILED DESCRIPTION OF INVENTION 
       [0022]    A transfer system  10 ′, of which, compared with  FIG. 1 ,  FIG. 2  shows just one side with the assembly structure  12 ′, comprises transport beams  16 , which are to be moved in three directions in a mutually orthogonal manner. For each type of motion, a driver engages the transport beam  16 , specifically one driver  26  for the advancement movement, one driver  28  for the transverse movement, in which the two transport beams  16  are moved towards, or as the case may be, away from each other, and one driver  30  for an upward or downward movement, for raising or lowering a workpiece. The driver  26  engages fixedly onto the transport beam  16 , while the transport beam can be moved backwards and forwards  16  relative to the drivers  28  and  30 , see arrows  32 . These different functionalities of the drivers  28  and  30  compared with the driver  26  as regards advancement movement of the transport beam  16  are reflected in a different mounting of the transport beam  6  in the drivers. The movement of the driver  26  and thus the advancement movement of the transport beam  16  is effected via a toothed belt system  34 . The toothed belt system  34  brings about a to and fro movement of driver  26  and transport beam  16  corresponding to the arrow  36 . The driver  26  is movable relative to the toothed belt system  34  in both directions orthogonal to the advancement direction, see the arrow  38  for lifting and the rear view of arrow  40  for movement vertical to the plane of the paper. 
         [0023]    The advancement movement thus takes place in an essentially conventional manner. 
         [0024]    A single motor  42  is envisaged for movement of the two other drivers  28  and  30 , which in the present case is a so-called combi drive: The motor  42  turns a shaft  44  corresponding to the arrow  46 , and is simultaneously also capable of moving the shaft  44  up and down, see arrow  48 . In order to convert the rotary movement of the shaft  44  into a translatory movement, a toothed wheel  50  is embodied on the shaft  44 , which intermeshes with a gear rack  52 . The rotation of the shaft  44  corresponding to the arrow  46  brings about a translatory movement of the gear rack  52 , which in  FIG. 2  takes place in a direction perpendicular to the plane of the paper, see arrow symbol  54 . The gear rack  52  is coupled to the driver  28 , so that its translatory movement accompanies a translatory movement of the transport beam  16 . This movement causes the two transport beams  16  to approach each other, enabling them to grab a workpiece (cf. representation of the two transport beams  16  in  FIG. 1 : In the case of transport system  10 ′, a second transport beam  16  is provided in a corresponding manner). The coupling of the driver  28  to the gear rack  52  is such as to enable an up and down movement of the driver  28  with an unchanged gear rack  52 , see arrow  56 . 
         [0025]    This up and down movement can for its part occur if the motor  42  moves the shaft  44  to and fro corresponding to the arrow  48 . The driver  30  is linked to the shaft  44  by means of a bracket  58 . The bracket is embodied so as to enable a relative movement in the direction perpendicular to the plane of the paper corresponding to the arrow symbol  60 . The mounting of the transport beam  16  in the driver  30  has already been mentioned above. 
         [0026]    In the transfer system  10 ′ it is the case that two types of motion, namely the transverse movement, movement of the transport beams  16  towards or away from each other, and the lifting movement, are effected by one and the same motor  42  (combi drive). In the case of the transfer system  10 ′, the motor  42  thus replaces two of the electric motors  18  which the transfer system  10  of the prior art has. The further type of motion, in this case the advancement movement of the transport beams  16 , is effected in the customary manner. Alternatively to the embodiment represented, it is also possible for the up and down movement to take place in an essentially conventional manner, and the rotary movement of the shaft of the combi drive to bring about the advancement movement. 
         [0027]    As already mentioned,  FIG. 2  shows just one side of the transfer system  10 ′. In the same way as the transfer system  10  of the prior art has three electric motors on both sides, the transfer system  10 ′ can also have a double-function motor  42  on the second side.