Abstract:
A boring and facing head, rotatively driven by the mandrel of a machine tool, with a turning tool mounted on a mounting slide, which may be controllably driven transversely of the axis (X) of the head body by a threaded shaft ( 12 ) operatively connected to a cylinder body ( 11 ), integral with a mandrel ( 4 ) and rotatably housing a ring gear ( 17 ), operatively connected to a gear wheel ( 19 ), driven by a controllable motor ( 8 ) and wherein the ring gear ( 17 ) comprises a circumferential tooth arrangement engaging with a gear wheel ( 52 ), integral with the driving shaft ( 12 ).

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention relates to a boring and facing head. 
         [0002]    As is known, such a head can be used in a machine tool and can be made by a numeric controlled system. 
         [0003]    The boring and facing head being coupled, either manually or automatically, to a mandrel of a machine tool, such as a central working unit or a special machine, to perform many freely selectable turning, facing or boring operations, the workpiece being machined being held locally stationary. 
         [0004]    In operation said head performs its chip removal operations by a turning tool, mounted on a mounting slide controllably driven transversely of an axis X of the machine tool mandrel. 
         [0005]    Boring and facing heads are well known in the prior art thereby they do not require a further detailed disclosure. 
         [0006]    However, since said heads comprise a comparatively complex epicycloidal mechanism for operatively driving the machining tool, the driving speed of the turning tool supporting slide is very low, even if modern machine tools would allow the machining tool supporting slide to be driven with a very high driving speed to drastically reduce the machine tool dead time and undesirable excessive heat generation, negatively affecting said head and its working accuracy. 
       SUMMARY OF THE INVENTION 
       [0007]    Accordingly, the aim of the present invention is to overcome the above mentioned drawbacks, by providing a boring and facing head, rotatively driven by the mandrel of a machine tool, including a turning tool mounted on a mounting slide, which may be controllably driven transversely of an axis X of a head body by a threaded shaft, operatively connected to a ring gear, integral with the mandrel and rotatively housing a gear wheel, driven by a controllable motor and wherein the ring gear comprises a circumferential tooth arrangement engaging with a gear wheel integral with the driving shaft. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    Further advantages and characteristics of the invention will become more apparent hereinafter from the following disclosure, claims and sub-claims, as well as the accompanying drawings, where: 
           [0009]      FIG. 1  is a schematic view showing a boring and facing head coupled to a mandrel of a machine tool, and with driving and numerical control means; 
           [0010]      FIG. 2  is a cross-sectional view of the head according to the present invention, with a driving motor driven by a driving screw element; 
           [0011]      FIG. 3  shows the subject boring and facing head with a further tool driving mechanism; 
           [0012]      FIG. 4  shows portions of the driving mechanism of  FIG. 3 , disengaged from the boring and facing head driving shaft; and 
           [0013]      FIG. 5  shows a further embodiment of the boring and facing head. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0014]      FIG. 1  shows a prior boring and facing head, which has been generally indicated by the reference number  1 . 
         [0015]    Said boring and facing head  1  comprises a bottom portion made as a well known driving slide  2  which may be driven (as shown by the arrow (f)), with respect to a fixed part  3  of the head. 
         [0016]    By a known machine tool mandrel  4 , driven by a respective driving motor  5  arranged in the machine tool, an operating tool  6  may be rotatively driven about an axis X. 
         [0017]    For rotatively driving the machine tool mandrel  4 , said machine tool controllable motor  5  is operatively coupled to a machine tool numerical control system  7 . 
         [0018]    To a further tool  6  driving mechanism, which will be disclosed hereinafter, arranged in the fixed part or body  3  of the head  1 , is operatively connected a further driving motor  8 , integral with the fixed part or body  3  of the head  1  for operatively driving a plurality of gear wheels, or belt driven wheels or pulleys, arranged in the body  3 , as it will be disclosed in a more detailed manner hereinafter. 
         [0019]    The motor  8  is also controlled by the machine tool numerical control system  7 . 
         [0020]      FIG. 2  is a cross-sectional view of the boring and facing head  1  and shows the machine tool mandrel  4  coupled to the rotary part of the head I. 
         [0021]    The fixed part or body  3  of the head  1  comprises a cylindric body  11 , supported by supporting bearings  10  and operatively coupled to said mandrel  4 . At the bottom part thereof, said cylindric body  11  is traversed by a threaded shaft  12  supported by respective supporting bearings  14  and  15 . 
         [0022]    In the cylindric body  11  is engaged, through further bearings  16 , a ring gear  17 , having a top toothed part  18  coupled to a bevel gear wheel  19  supported by further supporting bearings  20  and operatively connected to the motor  8  controlled through the machine tool numerical control system  7 . 
         [0023]      FIG. 3  shows the machining head  1 , driven, as above disclosed, by the mandrel  4  of the machine tool, which comprises a fixed part  3  engaged with a cylindric body  11  which, through said bearings  16 , engages said ring gear  17 , driven through a respective gear wheel  40  integral with a driving shaft  41  operatively coupled to a further driving motor  42  also controlled by the above disclosed machine tool numerical control system  7 . 
         [0024]    As shown, the gear wheel  40  ( FIG. 3 ) engages with the ring gear  17  which, in turn, is operatively connected to a further bevel gear wheel  52 , integral with said threaded shaft  12 , supported by the supporting bearings  14 ,  15 , as previously disclosed. 
         [0025]    As shown in  FIG. 4 , the front part of the driving shaft  42 , comprises an end portion  45  forming a clutch arrangement, which may be connected to a connecting assembly  46 , respectively engageable with and disengageable from said end portion  45 . 
         [0026]    The tool bearing slide driving motor comprises a shaft supporting a pinion directly engaging with a ring gear, centered on the rotary body and engaging with a further pinion in turn keyed on a ball recirculating worm screw, axially aligned with the slide driving direction and fixed to said slide. Thus, as the head rotary body is rotatively driven with the slide in a rest condition, said motor will be rotatively driven with such a rotary speed that said ring gear will in turn be driven with a same rotary speed as that of the rotary body. 
         [0027]    Thus, in a reference system integral with the rotary body rotary axis, the ring gear will be driven by a related driving speed corresponding to zero and the pinion and endless screw system will not be rotatively driven. 
         [0028]    Upon having synchronized the motor with the machine tool mandrel rpm&#39;s, it will be sufficient to either increase or decrease the motor rpm&#39;s to cause said slide to be either positively or negatively displaced. 
         [0029]    The main feature of the present invention is the synchronism concept applied to a boring and facing head mounted on a mandrel of a machine tool, which synchronism would be indispensable for driving a cross displacement of the tool mounting slide. 
         [0030]    Thus, the head according to the present invention does not comprise a differential or epicycloidal system thereby it is indispensable to provide a synchronism between the motor  8  rotary speed and the mandrel  4  rpm&#39;s. 
         [0031]    During a simultaneous synchronous rotation of the motor  8  with the mandrel  4 , the increasing or decreasing of the motor  8  rpm&#39;s will provide, through the gear wheel  19 , a corresponding rotary movement of the ring gear  17  with respect to the body  11  with a consequent movement of the gear wheel  52  and threaded shaft  12  and a related cross displacement of the tool mounting slide either in a positive or negative direction. 
         [0032]    In this connection it should be pointed out that the synchronism of the two rotary axes is directly controlled by the machine tool numerical control system  7 . 
         [0033]      FIG. 5  shows a boring and facing head, generally indicated by the reference number  1 , and having a modified structural construction. As is shown herein, the tool mounting slide  101  is operatively driven by a driving motor  102  arranged on the rear of the mandrel assembly  103 . The boring and facing head  104  is operatively coupled to the mandrel, which rotatively drives said head  104  through a driving gear wheel  105  in turn driven by a band  106  operatively connected to a wheel  107  in turn operatively coupled to a shaft of a driving motor  108 . 
         [0034]    Said head  104  is controllably driven by said motor  102  through a driving shaft  109  operatively coupled to the head  104  driveshaft, thereby rotatively driving a pair of bevel wheels  110  to in turn operatively drive the screw  11 , thereby causing said slide  104  to be radially fed. The slide movement being controlled by synchronizing the rotation of the motor  102  with that of the motor  108 . 
         [0035]    To provide a perfect synchronization of the machine tool motor  5  movements and the head motor  8 , both said motor  5  and motor  8  are synchronously controlled by said machine tool numerical control system  7 .