ROLLER MILL WITH A SYNCHRONISING DEVICE

Abstract

A roller mill for comminution of bulk material may include a first grinding roller and a second grinding roller that are arranged opposite one another and are configured to be driven in opposite directions. The grinding rollers may be positioned with a grinding gap therebetween. A fixed bearing unit may be configured to hold the second grinding roller, and a floating bearing unit may be configured to hold the first grinding roller. Attached to the floating bearing unit are hydraulic actuators for applying a force to the floating bearing unit. The hydraulic actuators are hydraulically connected to a synchronization device. The synchronization device has a plurality of hydraulic cylinders, each having a piston. The pistons may be connected to one another via a mechanical coupling such that movements of the pistons are coupled.

Claims

1.-12. (canceled)

13. 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.

14. The roller mill of claim 13 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 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.

15. The roller mill of claim 13 wherein the mechanical coupling is a plate.

16. The roller mill of claim 13 wherein each hydraulic cylinder has a gas chamber that is delimited by the piston.

17. The roller mill of claim 13 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.

18. The roller mill of claim 13 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.

19. The roller mill of claim 18 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.

20. The roller mill of claim 18 wherein each piston or each mechanical coupling has an elongated hole in which the piston rod is held.

21. The roller mill of claim 18 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.

22. The roller mill of claim 13 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.

23. The roller mill of claim 22 wherein the buffer unit is connected parallel to the synchronization device and the hydraulic actuators.

24. The roller mill of claim 13 wherein the synchronization device includes a cylinder with a gas chamber, wherein the mechanical coupling is configured as a piston and delimits the gas chamber of the synchronization device.

25. The roller mill of claim 24 wherein the gas chamber is filled with a compressible gas.

26. The roller mill of claim 25 wherein the compressible gas is nitrogen.

Description

DESCRIPTION OF THE DRAWINGS

[0021] The invention is explained in greater detail hereinbelow by means of multiple exemplary embodiments with reference to the accompanying figures.

[0022] FIG. 1 is a schematic illustration of a roller mill having a synchronization device in a longitudinal sectional view according to an exemplary embodiment.

[0023] FIG. 2 is a schematic illustration of a roller mill having a synchronization device in a sectional view according to a further exemplary embodiment.

[0024] FIG. 3 is a schematic illustration of a roller mill having a synchronization device in a cross-sectional view according to the exemplary embodiment of FIG. 1.

[0025] FIG. 4 is a schematic illustration of a roller mill having a synchronization device in a sectional view according to a further exemplary embodiment.

[0026] FIG. 5 is a schematic illustration of a roller mill having a synchronization device in a sectional view according to a further exemplary embodiment.

[0027] FIG. 1 shows a roller mill 10 having a first grinding roller 12 and a second grinding roller 14, wherein the grinding rollers 12, 14 are arranged opposite one another and are rotatable in opposite directions. A grinding gap 16 is formed between the grinding rollers 12, 14. The grinding rollers 12, 14 each have a substantially cylindrical roller base body 18, 20 and a drive shaft 22, 24 arranged coaxially therewith, the ends of which extend in the axial direction preferably beyond the respective roller base body 18, 20. Each of the grinding rollers 12, 14 is held in a bearing unit, wherein the bearing units are supported, for example, on a machine frame 29, which is not shown in full in FIG. 1. The first grinding roller 12 is held in a floating bearing unit 26, wherein the second grinding roller 14 is held in a fixed bearing unit 28. The fixed bearing unit 28 comprises two bearings 30, 32, which are each arranged at opposite roller ends and hold the drive shaft 24. The bearings 30, 32 are fixedly attached to the machine frame 29, so that they absorb forces in particular in the axial and radial direction of the grinding roller 14 and are not movable. The floating bearing unit 26 comprises two bearings 34, 36, which each hold one end of the drive shaft 22 of the first grinding roller 12. The bearings 34, 36 of the floating bearing unit 26 are held on the machine frame 29 such that they are movable linearly, preferably in a sliding manner. The bearings 34, 36 are preferably also fixedly attached in the axial direction of the first grinding roller 12. The bearings 34, 36 of the floating bearing unit 26 are each connected to a hydraulic actuator 38, 40, preferably to two hydraulic actuators. The hydraulic actuators 38, 40 serve in each case to apply to the first grinding roller 12, which is mounted in the floating bearing unit 26, a grinding force in the direction towards the second grinding roller 14. The grinding force is preferably oriented in a direction orthogonal to the delivery of the material into the grinding gap 16, in particular the grinding force runs in the horizontal direction. The floating bearing unit 26 is movable in particular in the direction of the grinding force applied by means of the hydraulic actuators 38, 40.

[0028] The hydraulic actuators 38, 40 are each supported with one end on a bearing 34, 36 and with their opposite other end on the machine frame 29. A movement of the respective bearing 34, 36 of the floating bearing unit 26 results in a corresponding movement of the respective hydraulic actuator 38, 40 attached thereto. Each hydraulic actuator preferably has a cylinder and a piston which is movably mounted therein, wherein the movement of the hydraulic actuator is to be understood, for example, as being a movement of the piston inside the cylinder. The roller mill 10 further has a synchronization device 42, which is connected to the hydraulic actuators 38, 40 via hydraulic lines 44, 46. The synchronization device 42 serves to couple, in particular to synchronize, the movement of the hydraulic actuators 38, 40, so that the bearings 34, 36 move in a coupled or the same manner and in particular misalignment of the grinding rollers 12, 14, where the grinding rollers are not oriented parallel to one another, is avoided or preferably limited. In particular, the synchronization device is configured such that a movement of one of the hydraulic actuators results in a corresponding movement of the other of the hydraulic actuators.

[0029] The synchronization device 42 has a plurality of hydraulic cylinders 50, 52, 54, 56. FIG. 2 is a cross-sectional view of the synchronization device 42 with, by way of example, four hydraulic cylinders 50, 52, 54, 56, which are arranged, by way of example, in a housing 48. It is likewise conceivable to provide only two hydraulic cylinders, six, eight or, for example, ten hydraulic cylinders. In each case half the hydraulic cylinders 50 to 56 is connected preferably to only one of the hydraulic actuators 38, 40. For example, in each case one, two or more hydraulic actuators 38, 40 are attached to each bearing 34, 36 of the floating bearing unit 26, wherein in each case half the hydraulic cylinders 50 to 56 of the synchronization device 42 is hydraulically connected preferably to only the hydraulic actuators 38, 40 of in each case one bearing 34, 36. For example, each hydraulic cylinder 50 to 56 of the synchronization device 42 is connected to exactly one hydraulic actuator 38, 40.

[0030] A piston 58, 60 is arranged in each of the hydraulic cylinders 50 to 56 so as to be linearly movable. The pistons 58, 60 are connected to one another via a mechanical coupling 62 such that their movement is coupled, wherein the pistons 58, 60 preferably perform a synchronous movement. In particular, all the pistons 58, 60 of the synchronization device 42 are fixedly connected to one another via the mechanical coupling 62. Preferably, the pistons 58, 60 each protrude from the respective hydraulic cylinder 50 to 56 with one end, wherein the end of the piston 58, 60 that protrudes from the hydraulic cylinder is fastened to the mechanical coupling 62.

[0031] The mechanical coupling 62 is, for example, a plate to which the pistons 58, 60 are fastened. The pistons 58, 60 are preferably oriented parallel to one another and orthogonally to the mechanical coupling 62, preferably the plate. The hydraulic cylinders 50 to 56 are connected to the hydraulic actuators 38, 40 via the hydraulic lines 44, 46. Preferably, the roller mill 10 has two hydraulic lines 44, 46, wherein one hydraulic line 44 is connected to the hydraulic actuators 38 of one bearing 34 of the floating bearing unit 26 and the other hydraulic line 46 is connected to the hydraulic actuators 40 of the other bearing 36 of the floating bearing unit 26. Preferably, each of the hydraulic lines 44, 46 is connected to only half of the hydraulic cylinders 50 to 56 of the synchronization device 42.

[0032] By way of example, the mechanical coupling 62 in the exemplary embodiment of FIG. 1 is in the form of a piston 62, wherein the synchronization device 42 has a cylinder 74 having a gas chamber 76, which is preferably filled with a compressible gas, such as, for example, nitrogen. The gas chamber 76 is delimited, by way of example, by two pistons 62, 78, wherein one of the pistons is preferably the mechanical coupling and the other piston 78 separates the gas chamber 76 from a hydraulic chamber 80. The hydraulic chamber 80 is preferably filled with a non-compressible hydraulic oil and in particular is connected via a hydraulic line to a hydraulic pump, not shown.

[0033] In the exemplary embodiment of FIG. 1, a buffer unit 64, 66 is arranged between the synchronization device 42 and each hydraulic actuator 38, 40. The buffer units 38, 40 are each connected via one of the hydraulic lines 44, 46 to the synchronization device 42 and the hydraulic actuators 38, 40. The buffer units 38, 40 are preferably substantially identical in form. Each buffer unit 64, 66 is in particular in the form of a single-acting hydraulic cylinder and has in each case a cylinder with a piston 68, which separates a gas chamber 70 from a hydraulic chamber 72 and is movable inside the cylinder. The gas chamber 70 is preferably filled with a compressible gas, such as, for example, nitrogen, wherein the hydraulic chamber is filled with a non-compressible hydraulic oil and is connected to the respective hydraulic line 44, 46, so that hydraulic oil is able to flow from the respective hydraulic line 44, 46 into the hydraulic chamber 72. The buffer unit 64, 66 serves as a buffer between the synchronization device 42 and the hydraulic actuators, so that the hydraulic actuators 38, 40 are uncoupled from the synchronization device 42 when the movement of the hydraulic actuators does not exceed a specific travel limit value. The travel limit value is preferably a deviation of the position of the hydraulic actuator relative to a zero position which corresponds to the desired size of the grinding gap.

[0034] During operation of the roller mill 10, the same hydraulic pressure is first applied to each of the hydraulic actuators 38, 40. In the case of a misalignment of the grinding rollers 12, 14, which can be caused, for example, by uneven loading of the grinding rollers in the grinding process, one of the bearings 34, 36 of the floating bearing unit moves away from the grinding gap 16, so that the hydraulic cylinder 38 or 40 connected to the respective bearing 34 or 36 is moved with the bearing 34, 36. A movement of at least one of the bearings 34, 36 results in a rise in the hydraulic pressure in one of the hydraulic lines 44, 46, wherein the piston 68 is pushed in the direction towards the gas chamber 70, so that the gas contained therein is compressed. The movement of the piston is limited, for example, by a stop in the hydraulic chamber 72 or by the compression limit of the gas, wherein, when the movement limit of the piston 68 is reached, the hydraulic actuators 38, 40 are again coupled with the synchronization device 42. The compressibility of the gas contained in the gas chamber causes a moderate pressure rise. The buffer unit 64, 66 permits a limited travel of the hydraulic actuator 38 or 40, so that a limited misalignment of the grinding rollers 12, 14, where the grinding rollers are no longer parallel, is permitted. Such a limited misalignment prevents damage to the grinding roller, wherein in particular damage to edge elements attached to the roller ends is prevented. As soon as the uneven loading, for example caused by fluctuations in the material composition, has passed, the hydraulic pressure is automatically adjusted to the starting value again by the buffer unit 64, 66.

[0035] It is likewise conceivable to configure the roller mill 10 of FIG. 1 without a buffer unit, so that a movement difference of the bearings 34, 36, in particular misalignment of the first grinding roller 12, is prevented completely.

[0036] FIG. 2 shows a further exemplary embodiment of a roller mill 10 having a synchronization device 42, wherein the same elements are provided with the same reference signs. The roller mill 10 of FIG. 2, in contrast to the roller mill of the exemplary embodiment of FIG. 1, has an alternative synchronization device 42. The hydraulic cylinders 50 to 56 of the synchronization device 42 each have a gas chamber 82, 84, which is delimited in each case by a piston 58, 60. The pistons 58, 60 of each hydraulic cylinder 50 to 56 separate a gas chamber 82, 84 from a hydraulic chamber 86, 88, wherein the hydraulic chamber 86, 88 is filled with an incompressible hydraulic oil and the gas chamber is filled with a compressible gas, such as, for example, nitrogen. The pistons 58, 60 each have respective piston rods 90, 92, which extend through the respective hydraulic chamber 86, 88 and are fastened to the mechanical coupling 62. The mechanical coupling 62 is, for example, a plate to which the piston rods 90, 92 are fixedly attached. The piston rods 90, 92 are each fastened at one end to the mechanical coupling 62 and held at their other, opposite end on the respective piston 58, 60. Preferably, each of the pistons 58, 60 has an elongated hole 94, 96 in which the end of the respective piston rod 90, 92 is held such that the piston 58, 60 and the piston rod 90, 92 are movable relative to one another in the direction in which the piston rod 90, 92 extends. It is likewise conceivable that the pistons 58, 60 are fixedly connected to the respective piston rods 90, 92 and the mechanical coupling 62 has a plurality of elongated holes in each of which a piston rod 90, 92 is movably held.

[0037] In the exemplary embodiment of FIG. 2, the misalignment of the two grinding rollers 12, 14 is made possible by the movable holding of the piston rod 90, 92 in the piston 58, 60 or the mechanical coupling, wherein the length of the elongated hole limits the movement difference of the bearings 36, 36, in particular the maximum misalignment.

[0038] FIG. 3 is a cross-sectional view of the roller mill 10 according to FIG. 1, wherein the same elements have the same reference signs. FIG. 3 shows the arrangement of the hydraulic actuators 38a and 38b, wherein only one of the hydraulic actuators 38 is visible in FIG. 1. By way of example, the hydraulic actuators 38a and 38b are arranged equally spaced apart from the center line of the grinding roller 12 and are each fastened to the bearing 34 of the floating bearing unit 26. Preferably, each hydraulic actuator 38a, 38b is connected via a hydraulic line 44a,b to exactly one hydraulic cylinder 50 to 56 of the synchronization device 42. Each of the hydraulic lines 44a,b has a buffer unit 64a,b.

[0039] FIG. 4 shows a further exemplary embodiment of a roller mill 10 having a synchronization device 42, wherein the same elements are provided with the same reference signs. The roller mill 10 of FIG. 4, in contrast to the roller mill of the exemplary embodiment of FIG. 2, has an alternative synchronization device 42. The piston rods 90, 92 are each movably attached at one end to the mechanical coupling 62 and are fastened at their other, opposite end to the respective piston 58, 60, or are formed in one piece therewith. The piston rods 90, 92 each extend, by way of example, through a bore in the mechanical coupling 62. Each piston rod 90, 92 has two stops for limiting the movement of the respective piston rod 90, 92, wherein the mechanical coupling 62 is arranged between the two stops of the piston rod 90, 92. The two stops are spaced apart from one another, so that a movement of the piston rod 90, 92 relative to the mechanical coupling 62 is possible. Preferably, one half of the plurality of piston rods 90, 92 of the synchronization device 42 is movably attached to the mechanical coupling 62 and the other half of the piston rods 90, 92 is fixedly connected to the mechanical coupling 62.

[0040] FIG. 5 shows a further exemplary embodiment of a roller mill 10 having a synchronization device 42, wherein the same elements are provided with the same reference signs. The roller mill 10 of FIG. 5, in contrast to the roller mill 10 of the exemplary embodiment of FIG. 1, has an alternative buffer unit 94. By way of example, the roller mill 10 of FIG. 5 has only one buffer unit 94, which is connected parallel to the synchronization device 42 and the hydraulic actuators 38, 40. The buffer unit 94 is preferably in the form of a double-acting cylinder, wherein one piston 96 separates two hydraulic chambers 98, 100 from one another. It is likewise conceivable to connect a plurality of buffer units 94 parallel to one another.

LIST OF REFERENCE SIGNS

[0041] 10 roller mill [0042] 12 first grinding roller [0043] 14 second grinding roller [0044] 16 grinding gap [0045] 18 roller base body [0046] 20 roller base body [0047] 22 drive shaft [0048] 24 drive shaft [0049] 26 floating bearing unit [0050] 28 fixed bearing unit [0051] 29 machine frame [0052] 30 bearing [0053] 32 bearing [0054] 34 bearing [0055] 36 bearing [0056] 38,a,b hydraulic actuator [0057] 40 hydraulic actuator [0058] 42 synchronization device [0059] 44,a,b hydraulic line [0060] 46 hydraulic lines [0061] 48 housing [0062] 50 hydraulic cylinder [0063] 52 hydraulic cylinder [0064] 54 hydraulic cylinder [0065] 56 hydraulic cylinder [0066] 58 piston [0067] 60 piston [0068] 62 mechanical coupling [0069] 64,a,b buffer unit [0070] 66 buffer unit [0071] 68 piston [0072] 70 gas chamber [0073] 72 hydraulic chamber [0074] 74 cylinder [0075] 76 gas chamber [0076] 78 piston [0077] 80 hydraulic chamber [0078] 82 gas chamber [0079] 84 gas chamber [0080] 86 hydraulic chamber [0081] 88 hydraulic chamber [0082] 90 piston rod [0083] 92 piston rods [0084] 94 buffer unit [0085] 96 piston [0086] 98 hydraulic chamber [0087] 100 hydraulic chamber