Mechanical analysis of material crushing

All mechanical crushing uses external force to be applied to the crushed materials to overcome the cohesive force between the material particles to cause the materials to be crushed.

There are two cohesive forces of materials: one cohesive force acts on the crystal particles inside the crystal; the other cohesive force acts between the crystal and the crystal, that is, it acts on the crystal interface. The physical properties of the two cohesive forces are the same, the difference is that the cohesion force is different, the former is many times larger than the latter.

The size of cohesion depends on the nature and structure of the crystal itself in the material block, and also has a lot to do with the dislocation and microcrack defects in the crystal structure. If you choose to crush the defects of the crystal material, you can not only save work, but also ensure the required particle size and reduce over-crushing. Reach

The purpose of such fragmentation is called “selective fragmentation”.

The technical method to achieve selective crushing is that the material to be crushed should be squeezed in all directions in the bulk material layer, while stress is induced at the edge of the crystal or crystallite, and the material block should be subjected to combined loads, including shear, bending and torsion. , It is best to have both stretching. If it is specific to the crusher, the material

The material is squeezed in all directions in the crushing cavity; the material blocks repeatedly impact each other or impact on the liner, the rapid transfer of the material block group; control the material layer to have a certain degree of density, and make the material from the crushing cavity to the exit, crushing The force is gradually increased. In addition, if high-frequency strong vibration is applied to the material layer, it can be

Make the material blocks change directions to each other, so that alternating shear and bending stresses can be generated in the material blocks. This crushing method is called forced internal vibration crushing.

Existing crushers, such as inertial vibrating cone crushers, use forced inner vibratory crushing, and some of the above methods are combined, so that selective crushing can be fully realized.