Principle of operation
Roller grinding mills, also referred to as bowl mill crushers or vertical mills have been used for crushing hard Materials already for many years. Roller grinding mills are used to reduce in size, e.g. limestone for cement production or coal in heating power stations. Various manufacturers worldwide offer roller grinding mills with similar principles of operation.
The material is reduced in size between a driven, rotating plate with a vertical axis, and a number of rollers with differently shaped outside diameters positioned above. The material is fed in over and over until it has been reduced to the specified grain size. The number, form and Arrangement of the rollers vary depending on manufacturer and specific application.
Grinding roller support
The support of the grinding rollers also varies depending on manufacturer and specific application of the roller grinding mill . Two types of support will be explained in the following.
In fig. 6, each grinding roller (as a rule, two grinding roller pairs per machine) is supported by two 0-arranged tapered roller bearings. The tapered roller bearing unit is supplied by FAG ready for mounting. The design takes into account the bearing load, the bearing seat tolerances and temperature influences on the bearing. The spacer ring between the two cones is machined to fit the housing collar width (between the cups) specified by the mill manufacturer. The bearing unit thus gets the required axial preload.
Taking into account the aforementioned criteria, the internal load distribution is checked using the FAG program DRV to ensure that the limiting values of stressing are not exceeded in operation.
The grinding roller in fig. 7 is supported by an X-arranged tapered roller bearing unit (locating bearing) and a cylindrical roller bearing (floating bearing). (As a rule, 2, 3 or 4 grinding rollers per machine are used in this machine type, depending on the specific application). The tapered roller bearing unit is supplied by FAG ready for mounting.