Factor analysis of prolonging the service life of mining equipment Henan Hongxing


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Factor analysis of prolonging service life of mine equipment

Mining equipment In the process of using, how to prolong the service life, improve the availability of equipment and prolong the overhaul time of equipment are mainly analyzed from the factors related to the overhaul of mining equipment, such as materials, surface processing of parts, fatigue and matching properties of parts materials.

 Mining equipment

1. Materials

Materials and heat treatment methods affect the service life of parts. The material selection of the parts should be based on the load nature and value, moving speed, temperature, lubrication conditions, corrosivity and manufacturing process. It can be seen from experience that the occurrence and evolution of all wear starts from the plastic deformation of the material. For example, the wear resistance of carbon steel increases with the increase of hardness and carbon content.

High hardness parts must have high wear resistance under the required surface finish. When the surface finish is low, the bulge is first worn off in the friction process, thus forming hard abrasive to intensify the wear.

In addition to high hardness, the parts bearing impact load must have good toughness. Because of the brittleness of materials with high hardness, the parts bearing impact load should not be high carbon steel, but low carbon steel or alloy steel, and surface treatment (quenching and tempering after carburizing) should be selected.

The graphite in cast iron has the function of lubrication, the wear resistance of cast iron is high, and the gap of graphite itself is easy to penetrate into lubricating oil. The strength and wear resistance of cast iron can be improved by adding Ni, Cr, Mn, Mo, B and other alloy elements and corresponding heat treatment. Chromium can improve the hardness, nickel can provide hardness and promote graphitization. Boron can produce a kind of high hardness carbide in cast iron structure, and its hardness increases with the increase of boron content, such as piston ring and cylinder liner of engine.

2. Surface machining of parts

The surface machining of parts refers to the surface finish, geometric tolerance and surface machining marks, etc. the surface finish affects the wear resistance of parts. During the running in period of the new machine, the rough protruding points of the parts occlude with each other, and the actual contact area is less than the calculated value, resulting in high pressure and temperature of the contact points, resulting in rapid wear of the protruding points and excessive fit clearance.

Surface finish also affects the durability of static fit and transition fit parts. When the rough surface is assembled, the peak of unevenness produces shear deformation, which makes the actual interference less than the design value, and the parts are easy to loose in use, thus reducing the service life of the equipment.

The corrosion of the components from the surface of the flotation machine is poor, such as scuffing. Due to the roughness of rough surface, the continuity of lubricating oil film is destroyed and the lubrication condition is deteriorated. However, considering from the lubrication principle of machine parts, it is easy to extrude lubricating oil from the surface of parts which is too smooth, which will make the lubricating film thinner and destroy the lubrication. Therefore, the surface of parts should be kept with proper smoothness.

3. Influence of coordination properties

The service life of mechanical equipment is related to the matching nature in the process of manufacturing and repairing. Taking the wear of liner as an example, the initial assembly clearance has been left in the repair and assembly. In the running in stage of the new machine, because the running in clearance gradually increases to the running in service clearance, the smaller the initial clearance and the running in service clearance, the longer the service life of the liner matching pair and the longer the time to reach the maintenance limit clearance. Wear during running in period is mainly related to surface finish (also related to running in specifications and methods), while smaller initial clearance can only be achieved through precision machining, but the repair and manufacturing costs of parts are increased. Therefore, within the scope of ensuring enough small fit clearance, the matching method is adopted in assembly inspection, and the tolerance range is relaxed during manufacturing and repair processing Select the exact fit clearance.

The smaller the actual clearance is not favorable in the field. On the contrary, if the lubrication value is less than allowable, it is unfavorable to the assembly clearance. For example, Babbitt alloy bearing bush, when the assembly clearance is less than 0.035, the engine is easy to hold the shaft and burn the bush. If the clearance between bearing bush is too small, oil film can not be formed between the shaft and the bearing bush to support heat dissipation; if the clearance between assembly and repair is too large, the lubricating oil with appropriate pressure will be removed from the excessive clearance, and it is difficult for the whole lubrication system to establish lubricating pressure and accelerate the wear of the whole machine. In the maintenance and assembly of equipment, the operation should be carried out according to the maintenance specification. Any reduction or expansion of the service gap (or interference) will cause adverse operating conditions for mechanical equipment, increase wear and reduce the service life of matching parts.

in summary, Mining enterprises The concept of predictive maintenance and active maintenance management of mechanical equipment is widely recognized and used. The wear causes, wear laws and early preventive measures of mining machinery and equipment are studied, which not only greatly prolongs the service life of the equipment, but also ensures the safety in production. We summarized some factors that affect the use of mining machinery in order to provide reference.

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