Physical principle of crushed ore crushing machine
Material of the grinding process is a very complex process of size reduced, involving many factors and variables cannot be estimated. For example: the strength of the material, shape, size, hardness, toughness, moisture, density and uniformity, as well as external conditions-force method, type of stress, the stress intensity, speed, particle group crushing process of instantaneous stresses interaction force and its distribution. Strength, for example, in respect of the same kinds of ore, the difference is very obvious, even very wide. Strength depends primarily on the material size of cohesion. Cohesion is generally divided into two kinds: the first cohesion role inside the crystals of materials, that is, between the crystal particle and the other cohesion between Crystal and crystal. Both cohesion of physical properties of the same, but is many times larger in value than the latter. Because of the complexity of crushing process still cannot be arrive at a unified, seamless, complete mathematical theory to describe the change.
But squeeze grinding technology of study on modern crushing theories and development is still inseparable from development. Smash physics is a complex area of science, which studies the materials by mechanical stress of structural change. About these stress the most important parameters are imposed by their distribution and velocity, specific mechanical properties of materials should also be taken into account. Crushed material is the result of structural changes, including the new surfaces and was crushed and items of internal defects.
Fracture mechanics is to describe rupture stress granule subjects. Fracture properties is to begin the formation for crack of critical point. Application of fracture mechanics determination of micro-cracks can occur and may cause a fracture mechanical stress of the material condition. Material fracture process of emergence and spread of the first crack, followed extension of crack until fracture. Materials breaking strength of the specimen at maximum the maximum crack measured by the number and size of the region functions. Know two decisions of micro crack propagation parameters: average size of micro-crack and fracture energy of rF, it is possible to calculate the fracture strength of materials, and when the external pressure exceeds the strength of materials, material will be broken. Fracture energy release per unit refers to as extended crack surface energy required. Fracture energy of about 5J/m2 for brittle materials, plastic material is lOJ/m2, while metal 500J/m2. This energy is more surface energy, generally 0. 05-0. 5J/m2, that is, damage exists on the surface of the van der Waals bond energy required is much higher. Difference between surface energy and fracture energy shows that on both sides to expand to expand the energy needed to crack, key than with the ideal surface spoilers so much larger the amount of energy. This difference can be explained by the cattle and imposed to crack force necessary, cracks near the edge in a high degree of stress concentration, and because of the irreversible energy loss caused by plastic deformation of the material itself. Fracture energy values given as aforesaid, the mechanical properties of materials more plastic, the greater the energy loss.