Power Analysis of the Process of Brittle Materials Destruction in Universal Crushing Machine With Roll Locker

Abstract

The processing of friable materials used in metallurgical industry for production of definite size classes requires operation of crushing machines, including single-roll machines. Parameters of crushing process are degree and efficiency of crushing. The crushing degree is estimated by the ratio of dimensions of the initial crushing and resulting pieces and depends on the size of gap between the roll and the fixed jaw. Crushing efficiency is determined by mass of material crushed by consumed electric energy unit, and depends mainly on strength of crushed material. In order to reduce energy consumption needed for crushing, a single-roll crusher was developed at Siberian State Industrial University with forced feeding of crushing piece into the fracture zone due to the locker located on the roll. Forces of technological resistance appearing during machine operation are the main initial values for machine drive power and structural elements strength testing, thus, the operation power analysis is an integral stage in the design of any machine, including a crushing one. In the present work, forces acting on a crushing piece from roll side and fixed jaw in vertical and horizontal planes are identified. Based on the results obtained, it was determined that internal compressive forces acting on piece of crushing material cause action of normal compressive stresses in a piece, as well as an internal torque effect, which causes shearing stresses action, i.e. a complex stress state is generated in a fractioned piece with simultaneous action of normal and shearing stresses, under which action a fractioning piece is destroyed. Thus reduction in energy consumption for crushing is achieved, with all other conditions being equal. It reduces energy consumption of a single-roll crusher with forced feeding of material into the crushing zone.

Mathematical Modeling and Multi-Criteria Optimization of Design Parameters for the Gyratory Crusher

“…The above Equation (7) shows that the required jaw profile is a logarithmic spiral. The establishing of this fact in our study is the first time it has been established.…”

“…The pieces may fall out of the crusher if they are below the radial plane CD at the level at which the width of the crushing chamber at the end of the working stroke is equal to the width of the output slot at the maximum withdrawal of the working roll, i.e., CD = AB . Based on this condition, using expression (7), we may find the angle α fall determining the dimensions of the "fall-out body":…”

“…Furthermore, the above works did not address the issue of optimizing the modes or parameters. The work in [7] studied the working process of a single-roll crusher used for crushing rocks. The article presents analytical studies of the forces acting on a piece of rock.…”

Drive power calculation of a crushing machine working in shear

“…Designs of single-roll crushers are known, in which a piece is fed into the gap between the roll and a solid stationary plate. In the process of work, a complex stress state is generated in the destroyed material, in which both compressive forces act on a piece of crushed material, causing the action of normal compressive stresses in the piece, and an internal torque that causes the action of tangential stresses [9]. Under the action of a complex stressed state in the material, the strength is estimated through the equivalent stress, the ultimate strength of which is less than under the action of only normal stresses [10].…”

Experimental study of fractional composition of pieces of brittle material during crushing in a single-roll crusher with block stop on the roll

“…Однако при увеличении степени дробления (то есть отношения размера 2r дробимого куска к величине зазора a между валком и неподвижной щекой) угол захвата α увеличивается и это может привести к тому, что вертикальная составляющая силы трения между валком и дробимым материалом будет направлена в сторону, противоположную от зазора между валком 2 и неподвижной щекой 3, при этом будет происходить проскальзывание куска 1 по поверхности валка 2 без захватывания куска в зону дробления. В этом случае при вращении валка упор 4 рабочей поверхностью соприкасается с куском и начинает давить на кусок: при этом возникает сила, действующая на кусок и направленная в сторону зазора, кусок материала принудительно подается в зону дробления и дробится [20].…”