Roller mill with a synchronising device

1. A roller mill for comminution of bulk material, the roller mill comprising:

a first grinding roller and a second grinding roller arranged opposite one another, wherein the first and second grinding rollers are drivable in opposite directions and are positioned with a grinding gap therebetween;

a fixed bearing unit configured to hold the second grinding roller;

a floating bearing unit configured to hold the first grinding roller;

hydraulic actuators attached to the floating bearing unit, the hydraulic actuators being configured to apply a force to the floating bearing unit; and

a synchronization device that is hydraulically connected to the hydraulic actuators, the synchronization device having hydraulic cylinders each of which has a piston, wherein the pistons are connected to one another via a mechanical coupling so that movements of the pistons are coupled.

2. The roller mill of claim 1 wherein the floating bearing unit includes two bearings that each hold an end of the first grinding roller, wherein at least one of the hydraulic actuators is attached to each of the two bearings, wherein half of the hydraulic cylinders of the synchronization device are attached to the at least one hydraulic actuator attached to a first of the two bearings and the other half of the hydraulic cylinders of the synchronization device are attached to the at least one hydraulic actuator attached to a second of the two bearings.

3. The roller mill of claim 1 wherein the mechanical coupling is a plate.

4. The roller mill of claim 1 wherein each hydraulic cylinder has a gas chamber that is delimited by the piston.

5. The roller mill of claim 1 wherein each hydraulic cylinder has a gas chamber and a hydraulic chamber, with the gas chamber and the hydraulic chamber being separated by the piston.

6. The roller mill of claim 1 wherein each of the hydraulic cylinders comprises a piston rod that is attached at a first end to the mechanical coupling and at a second end to one of the pistons.

7. The roller mill of claim 6 wherein each piston rod is held on the piston or the mechanical coupling such that the piston rod and the piston or the mechanical coupling are movable relative to one another.

8. The roller mill of claim 6 wherein each piston or each mechanical coupling has an elongated hole in which the piston rod is held.

9. The roller mill of claim 6 wherein each hydraulic cylinder has a gas chamber and a hydraulic chamber, with the gas chamber and the hydraulic chamber being separated by the piston, wherein the piston rod extends through the hydraulic chamber or through the gas chamber.

10. The roller mill of claim 1 comprising a buffer unit disposed between the synchronization device and the hydraulic actuators, wherein the buffer unit is configured to limit a movement difference of the hydraulic actuators.

11. The roller mill of claim 10 wherein the buffer unit is connected parallel to the synchronization device and the hydraulic actuators.

12. The roller mill of claim 1 wherein the synchronization device includes the hydraulic cylinder with a gas chamber, wherein the mechanical coupling is configured as the piston and delimits the gas chamber of the synchronization device.

13. The roller mill of claim 12 wherein the gas chamber is filled with a compressible gas.

14. The roller mill of claim 13 wherein the compressible gas is nitrogen.