Abstract:
In a roll grinding machine ( 2 ) for profile grinding of rolls with a constructionally simple device for a very precise adjustment of a grinding wheels ( 4 ) supported on a grinding spindle ( 7 ) tangentially with respect to a roll profile, the grinding spindle ( 7 ) is arranged in a rotatable sleeve ( 8 ) the longitudinal axis ( 9 ) of which is inclined at an angle ( 10 ) relative to the longitudinal axis ( 11 ) of the grinding spindle ( 7 ).

Description:
FIELD OF THE INVENTION 
     The invention relates to a roll grinding machine for profile grinding of rolls with a device for adjusting a grinding wheel supported on a grinding spindle tangentially with respect to a roll profile. 
     BACKGROUND OF THE INVENTION 
     Such roll grinding machines are used, e.g., for grinding working and support rolls used in sheet metal rolling mills, plastic plate rolling mills, and calenders. These rolls always have, as a rule, a shape which deviates from a pure cylindrical shape, and have a concave or crowned profile or a combination of both. During grinding of these profiles, it proved to be disadvantageous that a grinding wheel, because of its shaft or grinding spindle extending parallel to its axis, almost always grinds the roll with an edge and thus does not contact the roll along its entire surface. As a result, the grinding is effected with a very small longitudinal feed to avoid the formation of steps in the roll, with a corresponding resulting increase of the grinding time. 
     To eliminate this drawback since long ago, it is known to so pivot the grinding wheel-supporting spindle and to adjust it with respect to the roll that the grinding wheel always engages the profile tangentially to a most possible extent, whereby the grinding can be effected with approximately an entire wheel width. In order to achieve this, the roll grinding machines are designed with a possibility of a pivotal movement of the upper rest. This, however, requires not only an additional separation of the support. In addition, on one hand, it is very difficult to achieve an absolutely hysteresis-free pivotal movement about a stationary point and, on the other hand, to achieve simultaneously the necessary for the grinding process damping in the separation surface. 
     BRIEF SUMMARY OF THE INVENTION 
     Accordingly, an object of the present invention is a roll grinding machine of the above-described type in which the tangential adjustment of the grinding wheel is improved, and, in particular, is structurally simplified and, further, is possible with a greater precision. 
     This object is achieved according to the invention by arranging the grinding spindle in a rotatable sleeve formed, preferably, as an eccentric sleeve the longitudinal axis of which is inclined at an angle toward the longitudinal axis of the spindle. Thereby, unexpectedly, it became possible in a simple manner to adjust the grinding wheel with a reproducible precision of 1/100 μm by rotating the sleeve about the spindle, and actually independent of a cost-effective manufacturing of the roll profile, so that a desired adjustment is obtained with any geometry. Upon rotation of the sleeve, the grinding spindle, which is connected with an appropriate mechanism, is displaced with a main motion in the plan of the workpiece center and the grinding spindle center and is positioned at an angle, which corresponds to the amount of rotation, to the central axis of the workpiece. This angle can be calculated as a tangent to a curve by a NC-control unit of a high order computer and which is connected with the roll grinding machine. 
     According to a preferred embodiment of the invention, the point of intersection of both longitudinal axes lies in the center of the grinding wheel. Because of this stationary intersection point, the grinding spindle can be adjusted without a substantial change of the distance between the centers of the workpiece or the roll and of the grinding spindle. The precision of the tangential adjustment is further increased because of this. 
     When, advantageously, both the sleeve and the eccentric bushing are preloaded at their both ends, the precision of the grinding wheel adjustment is increased even further. For effecting the preloading, hydrostatic bearings or pre-loaded roller guides which, because of the rotational movement during the adjustment of the grinding spindle, can be used without any problem, are employed. A very large transmission ratio which is achieved according to the invention, between the rotational angle of the sleeve and the rotational angle of the grinding spindle, contributes, in addition, to that the adjustment movement of the grinding wheel upon its adjustment with respect to the roll profile, is reduced by this transmission ratio in proportion of about 1:100. 
     According to one embodiment of the invention, the sleeve is arranged on a grinding spindle-receiving eccentric bushing. In this way, the grinding spindle is not any more arranged directly in the inclined sleeve but in the inner eccentric busing so that a double eccentricity, which is particular suitable for fine adjustments, is achieved. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further particularities and advantages of the present invention follow from the claims and the following description in which an embodiment example of the subject matter of the invention is explained in detail. It is shown in: 
     FIG. 1 a schematic front view of a conventional per se known, roll grinding machine with a grinding wheel adjustable in accordance with a roll profile by a pivotal movement of an upper rest as practiced in the prior art; 
     FIG. 2 a detail of FIG. 1 showing a grinding wheel in different adjustable positions along the length of a to-be-ground roll; 
     FIG. 3 a variant of FIG. 2 showing a tangentially adjusted grinding wheel to the roll profile along approximately the entire wheel width; 
     FIG. 4 a substantially simplified front view of a grinding wheel supported on an eccentric sleeve and adjustable in accordance with the roll profile; 
     FIG. 5 a cross-sectional view along line V—V in FIG. 4; 
     FIG. 6 a detail of a schematic diagram of the kinematics during adjustment of the grinding wheel by rotation of the eccentric sleeve according to FIGS. 4 and 5; and 
     FIG. 7 a view corresponding to FIG.  5  and showing positioning of a grinding spindle which is arranged here with a double eccentricity. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In order to avoid the illustrated positioning of a grinding wheel  4  along the length of a roll,  1  in different operational positions, as shown in FIG. 2, with only an edge engaging the roll during grinding of the profile of the work or support roll  1  on a roll grinding machine  2  shown, for simplicity sake, schematically in FIG. 1 which shows essentially only an upper rest  3  and the grinding sheel  4 , and instead to achieve, according to FIG. 3, tangential positioning of the grinding wheel  4  shown here again in different operational positions in accordance with the conventional embodiment shown in FIG. 1, the entire upper rest  3  is pivoted about a point  5  in directions shown with a double arrow  6 . This pivotal movement brings with it the above-discussed drawbacks. 
     Achieving the tangential positioning of the grinding wheel  4  without changing the position of the upper rest  3 , i.e., without the need to pivot the same, is possible, with an embodiment according to FIGS. 4-6, by mounting a grinding spindle  7 , which supports the grinding wheel  4 , in a rotatable sleeve  8  formed as an eccentric sleeve, rotatable about the grinding spindle  7 , and having its longitudinal axis  9  extending at an angle  10  to a longitudinal axis of the grinding spindle  7 . In this embodiment example, the cross-sectional point  12  of both longitudinal axes  9  and  11  lies in the center of the grinding wheel and is, therefore, fixed. The grinding spindle  7  has its end, remote from the grinding wheel  4 , connected by drive means  13  with a drive of the roll grinding machine, not shown. 
     A zero position of the grinding wheel is shown in FIG. 4 in which points  14  and  15  taken on the longitudinal axis  9  of the sleeve  8  and on the longitudinal axis  11  of the grinding spindle  7  (compare FIG.  5  and FIG. 6) lie exactly at an angle of 90° to a line of  18  which connects, accordingly to FIG. 4, the roll center  16  with the grinding spindle center  17  which coincides with the points  15 . Upon beginning of rotation of the sleeve  8  by adjusting means recirculating ball screw drive  19 , shown schematically in FIG.  4  and connected, advantageously, with a high-order computer, the point  15  executes, accordingly to FIG. 6, a main motion in the plane of the longitudinal axis  11  of the grinding spindle  7 , with the cross-sectional point  12  of both longitudinal axes  9  and  11  remaining stationary. The grinding spindle  7  occupies a position corresponding to an adjustable value at an angle  10  to the roll center  16 , without changing the distance between the roll center  16  and the grinding spindle center  17  in any substantial manner. A large mechanical transmission ratio, which reduces the feed motion in proportion of about 1:100 exists between the pivot angle a of the sleeve  8  and the pivot angle β of the grinding spindle  7  (see the kinematics according to FIG.  6 ). 
     During the execution of the tangential adjustment of the grinding wheel according to FIG. 7, the grinding spindle  7  is arranged in an eccentric bushing  19 ′ which is concentrically surrounded by an outer sleeve  108  inclined relative to the longitudinal axis  11  of the grinding spindle  7 . In addition to the above-described very precise adjustment of the grinding wheel  4  with respect to the profile of the roll  1 , the double eccentricity, which is obtained by nested arrangement of the eccentric bushing  19 ′ and the inclined sleeve  108 , provides for a very precise adjustment of the tracking movement of the grinding wheel  4 . 
     The arrangement for effecting rotational movements for adjusting the grinding wheel  4  contemplates providing the sleeve  8  or  108  and the eccentric sleeve  19  at their respective opposite ends with respective hydraustatic bearings  20  and  21  which permit preloading of the sleeves  8  or  108  and  19 . The hydraustatic bearings  20  and  21  are shown schematically in FIGS. 5 and 7, without showing the conduits for the pressure medium. In both embodiments (FIG.  5  and FIG.  7 ), it is possible to tangentially adjust the grinding wheel  4  with respect to the profile of a respective roll with high precision, with the double eccentricity according to FIG. 7 enabling additional fine adjustment.