Abstract:
The invention relates to a hobbing machine for simultaneously hobbing n workpieces, comprising an n-fold milling head having n milling spindle axes that are parallel to one another, an n-fold tailstock and an n-fold workpiece spindle carrier having n workpiece spindle axes that are parallel to each other in a first horizontal main axis direction. The n-fold workpiece spindle carrier and the n-fold tailstock comprise n workpiece spindle carrier units or tailstock units which can be moved individually in a second horizontal main axis direction perpendicular to the first horizontal main axis direction along horizontal movement axes.

Description:
TECHNICAL FIELD 
       [0001]    The invention relates to a hobbing machine for hobbing n workpieces at the same time, having an n-fold milling head with n milling spindle axes which lie parallel to one another, an n-fold tailstock and an n-fold workpiece headstock with n workpiece spindle axes which lie parallel to one another in a first horizontal main axial direction. 
       PRIOR ART 
       [0002]    A 3-spindle production or tool milling machine from the company Wyssbrod Technologie AG for the material-removing circumferential machining of three workpieces at the same time is known under the designation CNC 7-4A. The three milling spindles are at a fixed spacing from one another and are connected to a central drive unit via a gear mechanism. The 3-fold tailstock and the 3-fold workpiece headstock are arranged movably on a common workpiece spindle and tailstock table. 
         [0003]    Highly precise undulating workpieces such as gearwheels and worms of gear mechanisms cannot be manufactured within the required tolerances on the known 3-spindle milling machines CNC 7-4A. The hobbing of highly precise gearwheel geometries which are hobbed on turned part blanks has therefore taken place up to now on 1-spindle hobbing machines with acceptance of a correspondingly reduced production output. 
       SUMMARY OF THE INVENTION 
       [0004]    The invention is based on the object of providing a multi-spindle hobbing machine of the type mentioned at the outset, by way of which multi-spindle hobbing machine highly precise gearwheel geometries may be milled efficiently. 
         [0005]    The achievement according to the invention of the object is reached by the fact that the n-fold workpiece headstock and the n-fold tailstock have n workpiece headstock units and tailstock units which can be displaced individually along horizontal displacement axes in a second horizontal main axial direction at right angles to the first horizontal main axial direction, where n is greater than 1. 
         [0006]    The precision setting according to the invention makes it possible to correct different milling diameters and pitch errors per milling tool and per milling spindle with respect to the workpiece axis. A correction of the cylindricity per milling spindle is also possible. Therefore, n, that is to say two, three or more, workpieces can be milled at the same time with high precision with regard to cylindricity. The output of parts is increased by a factor n, as a rule by a factor 2 or 3. 
         [0007]    The workpiece headstock units and tailstock units which are separate and can be moved individually in the second horizontal main axial direction make a simple and rapid correction possible of different milling diameters and of the conicity. Corrections can therefore be corrected via a simple control operation for the calibration of the tooth depth, even in the case of different milling diameters, and the conicity, as in the case of a 1-spindle hobbing machine. 
         [0008]    The n workpiece headstock units are preferably equipped with in each case one workpiece spindle drive unit. 
         [0009]    In one expedient embodiment, the n tailstock units are fixed on in each case one longitudinal carriage which can be displaced individually along horizontal displacement axes in the first horizontal main axial direction, and each longitudinal carriage is fixed on in each case one transverse carriage which can be displaced individually along the horizontal displacement axes in the second horizontal main axial direction. 
         [0010]    The n workpiece headstock units are preferably fixed on in each case one transverse carriage which can be displaced individually along horizontal displacement axes in the second horizontal main axial direction. 
         [0011]    The n-fold milling head is preferably fixed on a vertical carriage which can be displaced along a vertical displacement axis in a vertical main axial direction. 
         [0012]    In a preferred embodiment, the n-fold milling head is fixed on the vertical carriage such that it can be pivoted about a milling head pivot axis which lies in the second horizontal main axial direction. 
         [0013]    In a further preferred embodiment, an n-fold counterbearing milling head which can be displaced along a displacement axis which lies in the direction of the milling spindle axes lies opposite the n-fold milling head. 
         [0014]    The stability of the milling head allows milling to be carried out by way of floating hobs. If the milling head is designed for the use of end mills having a counterbearing milling head, a desired nonpositive connection between the milling head and the counterbearing milling heads and additional stability are achieved. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0015]    Further advantages, features and details of the invention result from the following description of preferred exemplary embodiments and using the drawing, in which, schematically: 
           [0016]      FIG. 1  shows a perspective view of a hobbing machine, 
           [0017]      FIG. 2  shows a plan view of the hobbing machine from  FIG. 1 , 
           [0018]      FIG. 3  shows a front view of the hobbing machine from  FIG. 1 , 
           [0019]      FIG. 4  shows a side view of the hobbing machine from  FIG. 1 , in the viewing direction M according to  FIG. 3 , and 
           [0020]      FIG. 5  shows a side view of the hobbing machine from  FIG. 1 , in the viewing direction N according to  FIG. 3 . 
       
    
    
     DESCRIPTION OF EXEMPLARY EMBODIMENTS 
       [0021]    A three-spindle hobbing machine  10  which is shown in  FIG. 1 to 5  for the simultaneous milling of three toothing systems on three workpieces in the form of turned parts comprises a torsionally rigid machine body  12  and stationary parts  14 ,  16 ,  18  of linear guides, which lie in the three main axial directions X, Y, Z which lie at right angles to one another, of an axial carriage or stand  20 , of a vertical carriage  22 , and of in each case three radial or transverse carriages  24 - 1 ,  24 - 2 ,  24 - 3  and  26 - 1 ,  26 - 2 ,  26 - 3  for in each case three workpiece headstock units  30 - 1 ,  30 - 2 ,  30 - 3  and tailstock units  32 - 1 ,  32 - 2 ,  32 - 3  of a 3-fold workpiece headstock  30  and tailstock  32 . 
         [0022]    The stationary linear guide parts  14  which are fixed on the machine body  12  lie in the first horizontal main axial direction X and, as parts of an axial carriage guide, make the linear displacement of the axial carriage  20  possible along a horizontal displacement axis X 1  in the first horizontal main axial direction X. 
         [0023]    The stationary linear guide parts  18  which are likewise fixed on the machine body  12  lie in the second horizontal main axial direction Y and, as parts of transverse carriage guides, make the linear displacement of the transverse carriages  24 - 1 ,  24 - 2 ,  24 - 3  and  26 - 1 ,  26 - 2 ,  26 - 3  for the workpiece headstock units  30 - 1 ,  30 - 2 ,  30 - 3  and tailstock units  32 - 1 ,  32 - 2 ,  32 - 3  possible along horizontal displacement axes Y 1 , Y 2 , Y 3 ; Y 11 , Y 12 , Y 13  in the second horizontal main axial direction Y. 
         [0024]    The stationary linear guide parts  16  which are fixed on the axial carriage  20  lie in the vertical main axial direction Z and, as parts of a vertical carriage guide, make the linear displacement of the vertical carriage  22  possible along a vertical displacement axis Z 1  in the vertical main axial direction Z. 
         [0025]    Each of the three workpiece headstock units  30 - 1 ,  30 - 2 ,  30 - 3  is mounted on in each case one transverse carriage  24 - 1 ,  24 - 2 ,  24 - 3  and can be moved individually along the horizontal displacement axes Y 1 , Y 2 , Y 3  in the second horizontal main axial direction Y by means of in each case one drive unit  36 - 1 ,  36 - 2 ,  36 - 3  which is assigned to each transverse carriage  24 - 1 ,  24 - 2 ,  24 - 3 . 
         [0026]    Each of the three tailstock units  32 - 1 ,  32 - 2 ,  32 - 3  is mounted on in each case one longitudinal carriage  28 - 1 ,  28 - 2 ,  28 - 3  and can be moved individually along the horizontal displacement axes X 11 , X 12 , X 13  in the first horizontal main axial direction X by means of in each case one drive unit  38 - 1 ,  38 - 2 ,  38 - 3  which is assigned to each longitudinal carriage  28 - 1 ,  28 - 2 ,  28 - 3 . Each of the three longitudinal carriages  28 - 1 ,  28 - 2 ,  28 - 3  is mounted on in each case one transverse carriage  26 - 1 ,  26 - 2 ,  26 - 3  and can be moved individually along the horizontal displacement axes Y 11 , Y 12 , Y 13  in the second horizontal main axial direction Y by means of in each case one drive unit  40 - 1 ,  40 - 2 ,  40 - 3  which is assigned to each transverse carriage  26 - 1 ,  26 - 2 ,  26 - 3 . The described combination of a longitudinal carriage and a transverse carriage is also called a cross carriage. 
         [0027]    In milling operation, the three tailstock units  32 - 1 ,  32 - 2 ,  32 - 3  of the 3-fold tailstock  32  lie opposite the three workpiece headstock units  30 - 1 ,  30 - 2 ,  30 - 3  of the 3-fold workpiece headstock  30  and form three parallel workpiece spindle axes A 1 , A 2 , A 3  which lie in the first horizontal main axial direction X. 
         [0028]    Each workpiece headstock unit  30 - 1 ,  30 - 2 ,  30 - 3  can be driven individually via in each case one drive unit  42 - 1 ,  42 - 2 ,  42 - 3 . The workpieces  50  which are clamped in between corresponding workpiece headstock units  30 - 1 ,  30 - 2 ,  30 - 3  and tailstock units  32 - 1 ,  32 - 2 ,  32 - 3  and the rotational axis of which lies in the corresponding workpiece spindle axis A 1 , A 2 , A 3  are accelerated to a predefined rotational speed by the three drive units  42 - 1 ,  42 - 2 ,  42 - 3 . 
         [0029]    A 3-fold milling head  34  is fixed on the vertical carriage  22  such that it can be pivoted about a milling head pivot axis B which lies in the second horizontal main axial direction Y. The 3-fold milling head  34  comprises three milling head units  34 - 1 ,  34 - 2 ,  34 - 3  which are equipped with in each case one dedicated main spindle drive  44 - 1 ,  44 - 2 ,  44 - 3  and have in each case one milling tool  48 - 1 ,  48 - 2 ,  48 - 3 . 
         [0030]    Together with the end-mounted milling tools  48 - 1 ,  48 - 2 ,  48 - 3 , the three milling head units  34 - 1 ,  34 - 2 ,  34 - 3  form three milling spindle axes S 1 , S 2 , S 3  which lie parallel to one another in a common plane and are at right angles to the milling head pivot axis B. 
         [0031]    The spacing between adjacent milling spindle axes S 1 -S 2  and S 2 -S 3  is substantially equally great for a 3-fold milling head within usual manufacturing tolerances and corresponds to the spacing between adjacent workpiece spindle axes A 1 -A 2  and A 2 -A 3 . In order to manufacture highly precise machined parts, it is therefore required to set the milling tools and the turned part blanks  50  individually to one another, which turned part blanks  50  are clamped in between the workpiece headstock units  30 - 1 ,  30 - 2 ,  30 - 3  and the tailstock units  32 - 1 ,  32 - 2 ,  32 - 3 . 
         [0032]    The setting of a predefined lateral spacing between mutually corresponding milling spindle axes and workpiece spindle axes takes place in practice by individual displacement of each individual tool headstock unit/tailstock unit pair, until the predefined lateral spacing between the milling and workpiece spindle axis pairs S 1 -A 1 , S 2 -A 2  and S 3 -A 3  is reached. 
         [0033]    The stability of the 3-fold milling head allows milling to be carried out by way of three floating hobs. 
         [0034]    The milling head  34  which is shown in the drawing and can be pivoted automatically about the B-axis is designed for the use of end mills with a counterbearing milling head  46 . The 3-fold counterbearing milling head  46  comprises three counterbearing milling head units  46 - 1 ,  46 - 2 ,  46 - 3  and can be displaced parallel to the milling spindle axes S 1 , S 2 , S 3  in a linear displacement axis (W-axis). The milling tools are changed via a hydraulic tool clamping means. An adjustment of the counterbearing milling head  46  can be made to the precise counterbearing diameter by way of the linearly movable W-axis. A desired nonpositive connection between the milling head  34  and the counterbearing milling head  46  and additional stability are therefore achieved. 
         [0035]    The shifting, that is to say the displacement movement of the milling head  34  in the direction of the milling spindle axes S 1 , S 2 , S 3  takes place by means of interpolation between the vertical axis Z 1  and the horizontal displacement axis or stand longitudinal axis X 1 . The shift software which is used automatically calculates the linear travel analogously to the oblique position of the three milling spindle axes S 1 , S 2 , S 3 . An intermediate carriage can thus be omitted and a stronger construction can be built. 
         [0036]    All the linear displacement axes X 1 , X 11 , X 12 , X 13 , Y 1 , Y 2 , Y 3 , Y 11 , Y 12 , Y 13 , Z 1  and the rotational axes S 1 , S 2 , S 3  and A 1 , A 2 , A 3  and the milling head pivot axis B are advantageously NC axes. 
       LIST OF DESIGNATIONS 
       [0000]    
       
           10  Hobbing machine 
           12  Machine body 
           14 ,  16 ,  18  Linear guide parts on  12   
           20  Axial carriage 
           22  Vertical carriage 
           24 - 1 , - 2 , - 3  Transverse carriages 
           26 - 1 , - 2 , - 3  Transverse carriages 
           28 - 1 , - 2 , - 3  Longitudinal carriages 
           30  Workpiece headstock 
           30 - 1 , - 2 , - 3  Workpiece headstock units 
           32  Tailstock 
           32 - 1 , - 2 , - 3  Tailstock units 
           34  Milling head 
           34 - 1 , - 2 , - 3  Milling head units 
           36 - 1 , - 2 , - 3  Drive units for  24 - 1 , - 2 , - 3   
           38 - 1 , - 2 , - 3  Drive units for  32 - 1 , - 2 , - 3   
           40 - 1 , - 2 , - 3  Drive units for  26 - 1 , - 2 , - 3   
           42 - 1 , - 2 , - 3  Drive units for  30 - 1 , - 2 , - 3   
           44  Main spindle drives for  34 - 1 , - 2 , - 3   
           46  Counterbearing milling head 
           46 - 1 , - 2 , - 3  Counterbearing milling head units 
           48 - 1 , - 2 , - 3  Milling tools 
           50  Workpieces 
         X 1  . . . Horizontal displacement axes in the X-direction 
         Y 1  . . . Horizontal displacement axes in the Y-direction 
         Z 1  Vertical displacement axis in the Z-direction 
         A 1 , A 2 , A 3  Workpiece spindle axes 
         S 1 , S 2 , S 3  Milling spindle axes 
         B Milling head pivot axis 
         W Counterbearing milling head displacement axis