Abstract:
The present invention relates to a processing head for processing machines, preferably tooth milling and tooth grinding machines, comprising a direct drive which is arranged in a processing head bed of a processing machine, wherein the direct drive comprises at least two motors actuatable in synchronism with each other.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates to a processing head for processing machines, preferably tooth milling and tooth grinding machines, according to the generic part of claim  1 . 
     In conventional processing machines, such as multifunctional machine tools, for example tooth milling and tooth grinding machines, the multiaxial movement and rotation of the milling spindle and the spindle head is controlled by remotely arranged motors, which employ synchronous belts, worm drives and wheels, bevel gears and spur gears or bevel gears which are functionally coupled with the spindle and the spindle head for rotating the spindle and the spindle head about two axes, individually or in combination (cf. for example U.S. Pat. No. 5,257,883). 
     From EP 0 885 081 B2 it is already known to directly drive a two-axis rotary head for a machine tool spindle without providing a transmission. 
     Such processing machine for processing toothings according to the prior art is shown in  FIG. 1  by way of example. 
     In  FIG. 1 , a tooth milling machine  10  is represented schematically, in which a milling tool  12  is mounted as processing head on a spindle  14  in a processing head bed  16 . The milling tool  12  is driven by an electric motor  18  via a gear train which is arranged on a side of the external milling head in the processing head bed  16 . The other side of the spindle  14  is supported by a counter bearing  20 , which likewise is arranged in the processing head bed. The milling tool  12  is used for processing an external toothing of a workpiece  22 , which is only schematically shown in  FIG. 1 . The spindle  14  carrying the milling tool  12  is driven in direction of arrow a. It can be swiveled in direction of arrow b, so as to possibly fabricate helical toothings. 
     SUMMARY OF THE INVENTION 
     The object of the present invention consists in providing a processing head for processing machines, which is in particular suitable for use on large machines and is of comparatively small size despite possibly high torque requirements. 
     In accordance with the invention, this object is solved by the combination of the features herein. Accordingly, a processing head for processing machines, preferably tooth milling and tooth grinding machines is proposed, in which the direct drive comprises two or more motors actuatable in synchronism with each other. Due to this solution, a double or multiple torque is available, so that the construction volume of the drive is decreased. Thus, a smaller diameter of the motors can be realized with doubled or multiplied torque. 
     Preferred aspects of the invention can be taken from the description herein. 
     Accordingly, the motors can be actuatable in a master-slave operation. Alternatively, a synchronous actuation is also possible. 
     In accordance with a particularly advantageous aspect of the invention, the motors are arranged to be shifted and clamped in the carriage of the processing head, i.e. in the processing head bed. As a result, the tool mandrel length can be adapted to the diameter of the workpiece to be processed. 
     The processing head of the invention can not only be set against the workpiece from outside, but is also suitable for forming an internal milling head. 
     As internal milling head/grinding head it can be pivotally arranged in a holder together with the processing head bed and the motors which are designed correspondingly small, so that helical toothings also can easily be realized here for internal toothings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further features, details and advantages of the invention can be taken from an embodiment illustrated in the drawing, in which: 
         FIG. 1 : shows a processing machine with a processing head in accordance with the prior art, 
         FIGS. 2 to 4 : show processing heads in accordance with the invention in different configurations, 
         FIG. 5 : shows a processing head in accordance with the invention in engagement with a workpiece, 
         FIG. 6 : shows a representation of the processing head of  FIG. 5  in engagement with a correspondingly larger workpiece, 
         FIGS. 7 and 8 : show an internal milling head in accordance with a further aspect of the present invention, and 
         FIG. 9 : shows an internal grinding head in accordance with an aspect of the present invention. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 2  shows a part of a processing machine  10  of  FIG. 1  in the configuration of the processing head in accordance with the invention. Said processing head includes processing head bed  16  which in its construction and arrangement corresponds to that in accordance with the prior art. In this known processing head bed  16  in accordance with the present invention the drive is formed of two motors  18  and  19  which each are arranged on both sides of the tool not shown in detail in  FIG. 2 . Tool holders  24  are flange-mounted directly to the motors  18  and  19 . The motors  18  and  19  can be shifted inside the processing head bed  16  in direction of the double arrows c and be fixed at a desired position by clamping, if necessary. Otherwise, the function of the shift axis is realized by shifting the two motors. As a result, different tools can be held by the tool holder  24  of the motors  18  and  19 . In  FIGS. 3 and 4 , different tools are shown by way of example. In the embodiment of  FIG. 3 , a hobbing cutter  12  is arranged on a mandrel which is mounted between tool holders  24  of the motors  18  and  19 . In this embodiment, the two motors  18  and  19  are moved apart very far and fixed in this position by clamping. This variant corresponds to the representation in  FIG. 6 , where the processing head bed  16  is arranged on a carriage  28  which is movable along the machine holder  30 . The hobbing cutter  12  here is used for processing a workpiece  22  with large diameter. It is used for manufacturing a corresponding external toothing. 
     In  FIG. 4 , on the other hand, the distance between the motors  18  and  19  is comparatively smaller. Here, a mandrel with a side milling cutter  13  is held by the tool holders  24 . 
     In  FIGS. 2 to 4 , the direction of rotation of the motors  18  and  19  and hence of the tool, for example of the hobbing cutter  12  in  FIG. 3  or of the side milling cutter  13  in  FIG. 4 , is indicated by the direction of arrow a. 
     In  FIG. 5 , a setting of the processing head of the present invention is shown, in which a workpiece  22  with smaller diameter is processed. For this purpose, a hobbing cutter  12  is clamped between the motors  18  and  19 , wherein the clamping length of the mandrel  26  on which the hobbing cutter  12  is mounted is comparatively shorter than the one in  FIG. 6 , with which a workpiece  22  with greater diameter was processed. With the double arrow d the direction of rotation of the workpiece  22  is indicated. The swivel arrow b indicates the possibility of swiveling the processing head bed, whereby a helical toothing can be produced on the workpiece  22 . 
     In  FIGS. 7 to 9 , another aspect of the processing head of the invention is explained. This is a processing head for processing the internal toothing of a workpiece  25 , as shown in particular with reference to  FIGS. 7 and 9 . The arrangement of both motors inside a processing head bed  16  of very short design in this variant (cf.  FIG. 8 ) provides for a very compact construction of the drive for the side milling cutter  18 , which can be driven in direction of rotation of the arrow a in  FIG. 8 . Laterally in the processing head bed  16  the motors  18  and  19  formed as direct drives are shown, which advantageously can be operated in a master-slave operation. Due to the dual drive of both motors, a very high torque can be provided by comparatively small motors. This compact construction as a whole can be held in a correspondingly provided recess in the holding arm  30  and be pivotally mounted there, so that via a non-illustrated swivel motor a swivel movement in direction of the double arrow f can be effected. This provides for processing helical toothings, without having to swivel the entire holding arm  30 . Rather, the axis of rotation for the internal milling cutter  13  for swiveling in direction of the double arrow f lies inside the processing head. As a result, the processing of helical toothings is substantially improved, since the disturbing contour can be avoided and comparatively smaller workpiece diameters can be processed especially with broad internal toothings. 
     The engagement of the side milling cutter  13  in the workpiece  25  to be processed is shown in  FIG. 7 .  FIG. 9  shows an alternative variant, in which a grinding disk  30  is mounted as processing tool inside the processing head bed  16  and can be driven by the at least two motors  18  and  19 . The entire processing head is gimbal-mounted and can be swiveled in the directions of arrow f and g by non-illustrated adjusting motors. 
     Even if the processing head of the invention is suitable in particular for use in large machines, the same can also profitably be used in comparatively smaller machines. Since the two motors are mounted in the processing head bed and fixed by clamping, the drive in the form of the two clamped motors can easily be pulled out of the processing head bed, if service is needed, and can be exchanged for a replacement insert.