The invention relates to a roll mill having a grinding plate rotatable about an axis of rotation, at least one grinding roller in rolling engagement with the grinding plate, and a main drive for driving the grinding plate. An auxiliary drive for driving the grinding plate, and a regulating device are also provided, the regulating device including at least one damping regulator which regulates the auxiliary drive in dependence on torque variations of the main drive and/or variations in the speed of rotation of the grinding plate.
1. A roll mill having:
a. a grinding plate ( 2 ) rotatable about an axis of rotation ( 1 ),
b. at least one grinding roller ( 3 , 4 ) in rolling engagement with the grinding plate, and
c. a main drive ( 5 ) for driving the grinding plate,
characterised in that at least one auxiliary drive ( 13 ) for driving the grinding plate ( 2 ), and a regulating device ( 15 ) are provided, wherein the regulating device includes at least one damping regulator ( 16 , 21 ) which regulates the auxiliary drive in dependence on torque variations of the main drive ( 5 ) and/or variations in the speed of rotation of the grinding plate ( 2 ).
2. The roll mill according to claim 1 , characterised in that the main drive ( 5 ) includes a planetary gear having sun wheel ( 6 ), planet wheels ( 7 , 8 ) and ring gear ( 9 ), the ring gear being rotatably arranged and the auxiliary drive ( 13 ) being provided for driving the ring gear.
3. The roll mill according to claim 2 , characterised in that the regulating device ( 15 ) regulates the auxiliary drive ( 13 ) in dependence on torque variations of the sun wheel ( 6 ).
4. The roll mill according to claim 1 , characterised in that a frequency converter ( 18 ) is provided for regulating the auxiliary drive ( 13 ).
5. The roll mill according to claim 2 , characterised in that the regulating device ( 15 ) includes a sensor ( 17 ) for detecting the torque of the sun wheel ( 6 ).
6. The roll mill according to claim 1 , characterised in that the regulating device ( 15 ) includes a sensor ( 20 ) for detecting the rotation speed of the grinding plate ( 2 ).
7. The roll mill according to claim 1 , characterised in that the regulating device ( 15 ) includes a state space controller.
8. A method of operating a roll mill comprising:
providing a roll mill having:
a. a grinding plate ( 2 ) rotatable about an axis of rotation ( 1 ),
b. at least one grinding roller ( 3 , 4 ) in rolling engagement with the grinding plate,
c. a main drive ( 5 ) for driving the grinding plate,
d. at least one auxiliary drive ( 13 ) for driving the grinding plate ( 2 ), and
e. a regulating device ( 15 ),
wherein the regulating device regulates the auxiliary drive in dependence on torque variations of the main drive 5 and/or variations in the rotation speed of the grinding plate 2 , in order to damp the torque variations of the main drive ( 5 ) and/or the rotation speed variations of the grinding plate ( 2 ).
9. The method according to claim 8 , characterised in that, to control the auxiliary drive ( 13 ), account is taken of the actual and a time-averaged torque of the main drive ( 5 ).
10. The method according to claim 8 , characterised in that, to control the auxiliary drive ( 13 ), account is taken of the deviation in the rotation speed of the grinding plate ( 2 ) relative to a reference speed.
11. The method according to claim 8 , characterised in that the torque measurement necessary for controlling the auxiliary drive ( 13 ) is effected via a high-dynamic angle of rotation measurement.
12. The method according to claim 8 , characterised in that any braking energy of the auxiliary drive ( 13 ) that may arise is used for energy purposes.
13. The method according to claim 8 , characterised in that the drive output required for driving the grinding plate ( 2 ) is provided by the auxiliary drive ( 13 ) in a proportion of 5 to 30%, preferably 10 to 20%.