Fatigue wear mechanism and countermeasures of iron ore crusher
Date：2019-10-08 16:39 Source：cementepcViews:
The fatigue wear process of iron ore crusher is the damage process of crack generation and propagation.According to the location of crack, according to the fatigue wear mechanism and countermeasures of iron ore crusher, the fatigue wear mechanism has the following two conditions:
1. Rolling contact fatigue wear.
The pitting and falling of rolling bearing and transmission gear are caused by rolling contact fatigue wear.Its characteristic is that after a certain number of cyclic contact stress action, pitting or shedding will occur, leaving pock-shaped pits on the surface of the friction pair, the depth of 0.1-0.2mm below.
2. Sliding contact fatigue wear.
The maximum shear stress is at 0.786b below the surface (b is half width of the plane contact area).There is the most severe plastic deformation, and the repeated deformation under the action of periodic loading will weaken the material locally, and the crack will appear first.Under the superposition of shear stress caused by sliding friction and shear stress caused by normal load, the maximum shear stress moves to the surface from 0.786b, forming rolling fatigue wear, and the depth of peeling layer is generally 0.2-0.4mm.
3. Reduce or eliminate the iron ore crusher fatigue wear countermeasures
3.1 the material.
The presence of non-ferrous inclusions in steel can easily cause stress concentration, and the edge of these inclusions is most likely to form cracks, thus reducing the contact fatigue life of the material.The microstructure and internal defects of materials also have important effects on wear and tear.
Generally, fine, uniform grains and spherical and uniform distribution of carbide are beneficial to improve the rolling contact fatigue life.After the treatment of bearing steel, the more residual austenite and the thicker the acicular martensite, the lower the beneficial residual compressive stress and cementite strength of the surface layer, and the more likely the microcracks will occur.Under the same condition of undissolved carbide, when the mass fraction of carbon in martensite is around 0.4% to 0.5%, the strength and toughness of the material match well and the contact fatigue life is long.For the undissolved carbides, through appropriate heat treatment, the amount of them tends to be small, small, uniform, avoid the appearance of coarse or banded carbides, is conducive to eliminating fatigue cracks.The contact fatigue resistance increases with the increase of hardness in a certain range.In addition, the surface hardness matching of two contact rolling bodies is also very important.
3.2 lining surface roughness.
Appropriate reduction of lining surface roughness is an effective way to improve the anti-fatigue wear ability, lining surface roughness requirements are related to the contact stress of lining surface, usually contact stress fire, or lining surface hardness is high, the lining surface roughness is required to be low.
In addition, the stress state of the lining surface, the accuracy of matching and the properties of lubricating oil all affect the fatigue wear rate.Generally, the lining surface stress is too large, fit gap is too small or too large, lubricating oil in the use of corrosive substances will aggravate fatigue wear.