Patent Application
20110272512
The present invention relates to a roller mill for grinding particulate material such as cement raw materials, cement clinker and similar materials, said roller mill comprising a grinding table which by means of a drive mechanism is rotatable about a vertical axis, at least one roller which is rotatably mounted on a shaft and being maintained in tangential direction relative to the grinding table by means of a guide mechanism and a support.
Roller mills of the aforementioned kind are generally known. During operation, the drive mechanism of the roller mill is quite often exposed to substantial loads which will reduce its service life, and which are ascribable to major variations in the torsional moment which often appear as high-frequency variations in the torsional moment. These variations in the torsional moment relate primarily to the flexibility in the mill drive mechanism and furthermore to the flexibility of the support of the guide mechanism which is often constituted by the frame or housing of the mill, and originating for example from variations in the tangential force imposed on the roller due to changes in the operating environment, such as changes in the grinding bed thickness etc. This flexibility in the guide mechanism support will enable the roller to move tangentially relative to the grinding table during the operation of the mill, leading to increased variation in the torsional moment of the drive mechanism due to the thereby existing mass and spring oscillation system.
It is the objective of the present invention to provide a roller mill by means of which the aforementioned disadvantage is eliminated or at least substantially reduced.
This is obtained by means of a roller mill of the kind mentioned in the introduction and being characterized in that it comprises a vibration-compensating device which is arranged in connection with the guide mechanism to ensure in interaction therewith that the roller is maintained in tangential direction relative to the grinding table.
It is hereby obtained that the roller is maintained in tangential direction relative to the grinding table independently of the flexibility of the guide mechanism support, so that the variations in the torsional moment of the mill drive mechanism and hence the loads on the drive mechanism are reduced. This is due to the fact that the vibration-compensation mechanism equalizes the elastic movement affecting the guide mechanism support when the tangential force, which is to be absorbed via the guide mechanism, varies due to a change in the operating environment, thereby actively preventing the roller from moving tangentially relative to the grinding table.
The vibration-compensating device may in principle be any suitable device compensating for vibrations. In one embodiment the vibration-compensating device may thus comprise a so-called active vibration damper (AVD).
In order to minimize the amount of energy which is lost, the vibration-compensating device should preferably function as a spring moving in counterphase with the tangential load imposed on the guide mechanism support, and hence the elastic movement of the guide mechanism.
The vibration-compensating device may comprise electrical as well as mechanical and hydraulic components and may be controlled for example by means of a measuring device indicating the absolute tangential position of the roller relative to the grinding table, or alternatively using a measuring device indicating the tangential force which is transferred via the guide mechanism or through the hydraulic pressure in hydraulic components such as hydraulic cylinders.
The guide mechanism of the roller mill may be constituted by any suitable guide mechanism. In one embodiment the guide mechanism may comprise a tangential arm which at its respective ends is rotatably connected to the shaft and the support, respectively, whereas in a second embodiment it may comprise a frame structure in which the rollers are suspended. The frame structure may include a housing of the roller mill.
Other details, objects, and advantages of the invention will become apparent as the following description of certain present preferred embodiments thereof and certain present preferred methods of practicing the same proceeds.
The invention will now be explained in further details with reference to the drawing, being diagrammatical, and where
In order to maintain the roller 4 in tangential direction relative to the grinding table 1 independently of the flexibility of the support 7 of the tangential arm, the roller mill comprises a vibration-compensating device 8 which is arranged so in connection with the tangential arm 6 that the vibration-compensating device 8 will equalize the elastic movement affecting the support 7 of the tangential arm 6 when the tangential force, which is to be absorbed via the tangential arm 6, varies due to a change in the operating environment. This will ensure that the roller does not move tangentially relative to the grinding table, and therefore does not contribute significantly to the variations in the torsional moment of the mill drive mechanism.
It is hereby obtained that the roller 4 is maintained in tangential direction relative to the grinding table 1 independently of the flexibility of the guide mechanism support so that the variations in the torsional moment of the mill drive mechanism and hence the wear on the drive mechanism are reduced. This is due to the fact that the vibration-compensation mechanism equalizes the elastic movement affecting the guide mechanism support when the tangential force, which is to be absorbed via the guide mechanism, varies due to a change in the operating environment, thereby actively preventing the roller 4 from moving tangentially relative to the grinding table. In one embodiment the vibration-compensating device 8 may comprise a so-called active vibration damper (AVD).
While certain present preferred embodiments of the roller mill and certain embodiments of methods of practicing the same have been shown and described, it is to be distinctly understood that the invention is not limited thereto but may be otherwise variously embodied and practiced within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| PA 2009 00138 | Jan 2009 | DK | national |
This application is the United States national stage under 35 U.S.C. §371 of International Application No. PCT/IB2010/050339, filed on Jan. 26, 2010, which claimed priority to Danish Patent Application No. PA 2009 00138, filed on Jan. 30, 2009. The entirety of these applications is incorporated by reference herein.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB2010/050339 | 1/26/2010 | WO | 00 | 7/11/2011 |
