The wear of hydraulic parts is usually as follows:
1. Friction and wear: during the operation of the hydraulic parts, the hard pollution particles with the same size as the clearance between the moving pairs are the most dangerous. At this time, the motion between the moving pair of the hydraulic parts and the hard polluted particles is just like the principle of the grinder. They continuously cut the material on the surface of the moving pair, so that the clearance of the moving pair of the hydraulic parts increases, resulting in the increase of leakage. At the same time, it also produces more metal particles that have been cut down, and a vicious cycle.
2. Erosion and wear: when the hydraulic medium flows at a high speed, it will drive the contaminated particles to impact the edge and surface of the parts together, just like the shot peening process, which will make the surface materials of the parts fall off, resulting in changes in the shape and clearance of the parts. At the same time, more metal particles are produced, resulting in a vicious cycle.
3. Adhesive wear: when the viscosity of heavy load and low speed or hydraulic medium is low, the thickness of oil film between moving pairs will be reduced, so that the metal surfaces are in direct contact, and some surface bulges will be bonded or inlaid together. When the hydraulic parts are running, these bonding or inlay points will be cut off, forming new metal particles and mixing them into the hydraulic medium.
4. Fatigue damage: during the operation of hydraulic parts and hydraulic auxiliary parts, they are generally affected by alternating stress. Under the action of alternating stress, the material will crack, resulting in fracture and more metal particles. From the above analysis, it can be seen that the hydraulic medium pollution (particle type pollution) is the main cause of the wear of hydraulic parts, and leads to more metal particles, making the hydraulic medium pollution more serious, forming a vicious cycle.
So, where did the pollution in the original hydraulic medium come from?
1. The hydraulic elements and accessories are not clean: when the hydraulic system is assembled, there is pollution inside the hydraulic elements and accessories. If they are not cleaned, or do not know the situation, they will be installed into the system.
2. Pollution caused by external invasion: including pollution caused by no attention during system assembly; pollution brought in during system operation, such as from piston rod and air filter; pollution brought in during maintenance; pollution brought in during refueling of oil tank, etc.
3. Pollution caused by L + L during the operation of hydraulic system: such as carbonization deterioration of hydraulic medium, wear of hydraulic parts, etc., will not be described in detail.
Therefore, we must start from the above points to solve and put an end to the problem of pollution sources. Finally, look at how contamination exists in hydraulic media. Pollution exists in suspension, dissociation and dissolution in hydraulic medium.
Suspension: hard particle pollution, such as emery, chips, worn down metal particles and their oxides, most of the air, etc., are in the form of suspension in the hydraulic medium. The air suspended in the hydraulic medium has a great influence on the elastic modulus of the hydraulic medium, which greatly reduces the elastic modulus of the hydraulic medium.
Dissolution: a small amount of water and air exists in the form of dissolution in the hydraulic medium. Water and air dissolved in hydraulic medium have little influence on the performance of hydraulic medium.
Free: most of the water is in the form of free hydraulic medium. The water free from the hydraulic medium earlier has little influence on the performance of the hydraulic medium.
-This article is from the love hydraulic forum, original address: http://www.iyeya.cn/thread-48285-1-1.html
