by Gao Yangyang and Dr Wu Wenbin, Grain and Oil Machinery
Research Institute, Henan University of Technology, China
The grinding roll system used within roller mills consists of grinding rolls,
bearings, a bearing seat, inter-roll transmission mechanism and clutch rolling
and distance adjustment mechanism (See Figure 1).
In the actual work operations of the mill, the vibration amplitude of the roll
produced by the defect of the roll grinding system and the impact of the load
is called the stability of the roll grinding system. The grinding roll exerts a
grinding effect on material, primarily through friction and extrusion.
The smooth operation of the grinding roll system is the key to ensure the
grinding effect of the mill is carried out efficiently and properly. The poor
stability of the grinding roll system will produce a periodic load/pressure on
the grinding roll, increasing the friction force between the two rolls and the
material, generating excessive friction heat and increasing energy consumption,
resulting in wear and tear on the roll surface and reducing the grinding
effect.
The service life of grinding rolls and the vibration of grinding rolls causes
changes within rolling distance, seriously affecting the crushing effects of
material, changing the roughness of grinding materials, increasing the
temperature of grinding materials and the instability of centrifugal grinding
rolling distance will affect the pulverising rate of the grinder.
The low pulverising rate will aggravate the load of follow-up equipment,
shorten the service life of equipment parts, reduce the output of the mill and
make the pulverising rate too high. The quality of the grinding roll is reduced
and the wear of the grinding roll is aggravated (See Figure 2).
The main factors affecting the stability of the grinding roll system are the
manufacturing accuracy of the grinding roll, bearing accuracy, feed uniformity,
assembly accuracy and clutch rolling mechanism. Other factors can also be at
play here.
The theoretical analysis and experimental results show that the working
stability of the roller system directly affects the output and fineness of the
mill as well as the temperature of the mill, energy consumption, the range of
the processed materials, the shape and distribution of the particles and the
life of the components. At the same time, it will increase the vibration and
noise of the mill and deteriorate the workshop environment.
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