EP2081689B1 - Roller mill - Google Patents

Description

The invention relates to a roller mill with at least one grinding roller and a rotatable grinding plate.

From practice roller mills are known in a variety of configurations. In one embodiment, the grinding roller is fixed to one end of a rotatable shaft which is supported outside the mill in a spherical roller bearing. In another embodiment, a power arm is provided, which is supported pivotably and non-rotatably in a bearing, wherein the grinding roller is rotatably mounted at one end of the power arm. Further, means for applying a force to the power arm are provided to adjust the grinding pressure exerted by the grinding roller. The means for exerting a force on the power arm are formed in many applications by spring elements. To be able to vary the grinding pressure better and to be able to set larger grinding pressures, however, hydraulic cylinders are often used.

In the JP-A-2002159874 This hydraulic cylinder is formed by a hinged and articulated connected to the power arm pull cylinder.

From the JP-A-2000 312832 Further, a coal mill is known in which the power arm is in operative connection with a pressure cylinder to adjust the grinding pressure exerted by the grinding roller. The cylinder is fixedly mounted on the housing wall, so that the cylinder piston protrudes into the mill interior and there transmits the force via a guided in a sleeve punch on the power arm. Since the power arm is mounted pivotably, occur in the region of the contact point on high transverse forces that must be absorbed by the sleeve.

The DE 742 912 C describes a spring roller mill with mounted outside of the mill housing, pushed by springs against the grinding path commuting. Furthermore, from the US-A-4,610,401 a roller mill with a milling roller mounted on a power arm known, wherein via a pressure cylinder, a force is transmitted to the power arm to adjust the pressure exerted by the grinding roller grinding pressure. The contact point at which the force is transmitted to the power arm, is located within the mill interior.

The invention is based on the object to find a new design for the introduction of a force on the power arm.

According to the invention, this object is solved by the features of claim 1.

The roller mill according to the invention consists essentially of at least one grinding roller and a rotatable grinding table, which are arranged in a mill interior and a power arm which is pivotally and rotatably supported in a bearing, wherein the grinding roller is rotatably mounted at one end of the power arm and further means for Applying a force to the force arm are provided, which comprise a pressure cylinder which is in operative contact with the force arm to adjust the grinding pressure exerted by the grinding roller. The contact point at which the force of the printing cylinder is transferred to the power arm, it is outside the mill interior. At least one thrust bearing is provided between the pressure cylinder and the power arm, which allows a relative movement between the pressure cylinder and the power arm.

A printing cylinder can be made smaller and more compact compared to a pull cylinder, whereby installation space is saved. An arranged outside the mill interior contact point also has the advantage that it is exposed to lower wear, since there is no dust and no high temperatures.

Further embodiments of the invention are the subject of the dependent claims.

According to a preferred embodiment, the pressure cylinder is arranged fixed. A fixed cylinder is on the one hand more compact and reduces the moving masses of a reel unit, which has a favorable effect on the vibrations.

In addition, the printing cylinder is expediently aligned perpendicular to the connection between the bearing and the grinding roller, whereby an optimal power transmission is possible. Furthermore, the printing cylinder is preferably arranged in a central region between the grinding roller and the bearing.

The thrust bearing can in particular have a first and a second pressure surface for exerting a sliding movement, wherein the coefficient of friction is preferably less than 0.2. With the thrust bearing, the relative movement between the fixed pressure cylinder and the pivotable power arm can be compensated so far that the forces acting on the impression cylinder transverse forces are minimized. In a further embodiment of the invention, a third and a fourth pressure surface are also provided for exercising a pivoting movement, thereby further minimizing the transverse forces. Due to the arrangement of the thrust bearing outside of the mill interior, a complex sealing of the bearing is not required.

Further advantages and embodiments of the invention will be explained in more detail below with reference to the description and the drawing.

Fig. 1

eine geschnittene Teilansicht der Rollenmühle,

Fig. 2

eine Prinzipdarstellung der Rollenmühle,

Fig. 3

eine geschnittene Teilansicht im Bereich der Kontaktstelle, an der die Kraft des Druckzylinders auf den Kraftarm übertragen wird.

In the drawing show

Fig. 1

a sectional partial view of the roller mill,

Fig. 2

a schematic representation of the roller mill,

Fig. 3

a sectional view in the region of the contact point at which the force of the printing cylinder is transmitted to the power arm.

In the Fig. 1 Roller mill shown consists essentially of a grinding roller 1 and a rotatable grinding table 2, which are arranged in a limited by a housing 3 mill interior 4. Furthermore, a power arm 5 is provided, which is pivotable and rotationally fixed in a bearing 6 designed as a fixed bearing is supported, wherein the grinding roller 1 is rotatably mounted at the opposite end of the power arm.

Further, means for applying a force to the power arm 5 are provided to adjust the pressure exerted by the grinding roller. This means comprises a pressure cylinder 7, which is fixedly arranged and acts approximately vertically to the line connecting bearing 6 and grinding roller 1 on the power arm 5. The impression cylinder 7 is preferably formed by a plunger cylinder. A contact point 8 at which the force of the printing cylinder 7 is transmitted to the power arm 5, is located outside of the mill interior 4th

In the illustrated embodiment, the pressure cylinder 7 acts in a central region between the grinding roller 1 and bearing 6 on the power arm 5. Within the scope of the invention, it would also be conceivable that the positions of bearing and pressure cylinder are reversed.

Furthermore, the power arm 5 is formed in a straight line in the illustrated embodiment, but also bent arms are considered in principle.

The bearing 6 is preferably formed by an axial spherical plain bearing, wherein in particular two mutually juxtaposed axial spherical plain bearings are used, which can be braced against each other, whereby the bearing clearance can be minimized. The grinding roller 1 at the other end of the power arm 5 is mounted via two tapered roller bearings 9 mounted in an O arrangement, wherein a lubricant space 10 of the tapered roller bearings 9 extends to a region outside of the mill interior 4 and is sealed there.

As can be seen from the schematic diagram of the Fig. 2 results, the bearing 6 allows a tilting movement of the power arm 5 by an angle α. It thus comes to a relative movement between the fixed pressure cylinder 7 and the power arm. 5 Since the pressure cylinder 7 is in constant operative contact with the power arm 5, it is therefore in the region of the contact point due to the relative movement to shear forces. In order to compensate for the relative movement between the impression cylinder 7 and the force arm 5, a thrust bearing 10 is provided that allows a relative movement between the impression cylinder and the power arm. The thrust bearing is in Fig. 3 shown in more detail and has a first and a second pressure surface 10a, 10b for exerting a sliding movement, wherein by suitable selection of the sliding pair a coefficient of friction is provided smaller than 0.2. In order to further reduce the initiation of the transverse forces on the cylinder 7, a third and a fourth sliding surface is also provided for exercising a pivoting movement. Again, the coefficient of friction can be minimized by suitable sliding mating. In Fig. 3 are shown in solid lines the center position of the power arm and with dotted lines the two extreme positions of the power arm in conjunction with the thrust bearing.

With this design of the thrust bearing, the power transmission from the impression cylinder to the power arm can be done in a very compact manner.

In the experiments underlying the invention has also been shown that the ratio of the distance a between the impression cylinder 7 and grinding roller 1 to the distance b between the impression cylinder 7 and bearing 6 in the range of 1: 0.9 and 1: 1.2, preferably in Range of 1: 1.0 and 1: 1.1 should be in order to keep the forces acting in the bearing 6, the pressure cylinder 7 and the corresponding abutments forces as small as possible. As a result, corresponding weight reductions are possible in the elements involved.

Claims (10)

1. Roller mill having at least one mill roller (1) and a rotatable mill platen (2), which are arranged in a mill inner space (4), and a moment arm (5) which is retained so as to be pivotably movable and rotationally secure in a bearing (6), with the mill roller (1) being supported in a rotatable manner at one end of the moment arm and there further being provided means for applying a force to the moment arm which are in operative contact with the moment arm in order to adjust the pressure which is applied by the mill roller, the contact location (8) at which the force is transmitted to the moment arm (5) being located outside the mill inner space (4),
   characterised in that the means for applying the force to the moment arm comprise a pressure cylinder (7) which is in operative contact with the moment arm in order to adjust the pressure applied by the mill roller,
   and in that there is provided between the pressure cylinder and the moment arm (5) at least one pressure bearing (10) which allows relative movement between the pressure cylinder (7) and the moment arm (5).
2. Roller mill according to claim 1, characterised in that the pressure cylinder (7) acts on the moment arm (5) in a central region between the mill roller (1) and the bearing (6).
3. Roller mill according to claim 1, characterised in that the pressure bearing (10) has a first and a second pressure face (10a, 10b) in order to apply a sliding movement and a third and a fourth pressure face (10c, 10d) in order to apply a pivoting movement.
4. Roller mill according to claim 1 or claim 3, characterised in that the pressure bearing (10) has a first and a second pressure face (10a, 10b) which allows a sliding movement with a friction coefficient which is less than 0.2.
5. Roller mill according to claim 1, characterised in that the pressure cylinder (7) is arranged so as to be fixed in position.
6. Roller mill according to claim 1, characterised in that the pressure cylinder (7) is orientated perpendicularly relative to the connection between the bearing (6) and the mill roller (1).
7. Roller mill according to claim 1, characterised in that the bearing (6) of the moment arm (5) is formed by an axial spherical plain bearing.
8. Roller mill according to claim 1, characterised in that the moment arm (5) is constructed so as to be rectilinear.
9. Roller mill according to claim 1, characterised in that the pressure cylinder (7) is formed by a plunger cylinder.
10. Roller mill according to claim 1, characterised in that the relationship of the distance (a) between the pressure cylinder (7) and the milling roller (1) to the distance (b) between the pressure cylinder (7) and the bearing (6) of the moment arm (5) is in the order of 1:0.9 and 1:1.2, preferably in the order of 1:1.0 and 1:1.1.

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