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The oil film becomes thinner, the strength decreases, the oil film is severely damaged, and the metal is in direct contact with the metal. The small particles welded together are torn from the tooth surface, causing the metal to fall quickly. Because the relative speed of the top surface of the tooth near the pitch line is relatively large, the glue first occurs on the tooth surface, which is characterized by tearing, wrinkles and pulling grooves along the sliding direction. This is a heavy-duty gear. The main aspects that should be noted.
As a result of the oil film destroying the direct friction between the metal and the metal, more heat is generated, which accelerates the rise of the oil temperature, accompanied by excessive wear or gluing. An increase in oil temperature can also cause extreme pressure components (including sulfides) in the lubricant to decompose, oxidize or deteriorate.
Reduce the resistance to gluing. The working temperature of the friction surface has a great influence on the performance of the boundary film. When the first critical temperature is reached, the adsorption film softens, loses and falls off, so that the lubricating oil is reduced, and the wear rate and friction coefficient increase. At the second critical temperature, the lubricating oil is completely decomposed, and the friction pair will be seriously stuck or even killed. Since the frictional heat is proportional to the PV (P-pressure, V-relative speed) value, limiting the PV value is the main measure to control the operating temperature of the friction surface. Reasonable selection of friction materials and lubricants to improve the surface finish, adding oil additives and extreme pressure additives to the lubricating oil can increase the strength of the boundary film. Extreme pressure additives (sulfur, phosphorus, oxygen) have high melting point and high temperature strength. Therefore, low temperature oil resistance (good film loss) and high temperature rely on chemical reaction film. Maintenance Method: The only way to eliminate overload failure is to reduce the unit load to within the rated load capacity of the gear.
1) Ensure that the overloaded original is in good condition, suitable oil quantity and good circulation system. 2) Use a practical anti-adhesive lubricating oil pressure additive. 3) Repair the gear surface in time. This includes the polishing of the teeth and the hardening of the damaged parts to improve the contact fatigue limit and the anti-adhesive ability, and reduce the friction coefficient. 4) Strictly control the oil temperature. Once it is close to the upper temperature limit, stop immediately and reduce the temperature; divide the oil viscosity in summer and winter; check the temperature regulator (such as heat exchanger) to ensure it is in good condition; use external fan to speed up the cabinet. Surface heat dissipation. 5) Check in time (oil quality, oil, gearbox) and make records to provide real data for routine maintenance. 6) Eliminate installation errors such as skew in the device, improve the accuracy of the device, including inspection and replacement of bearings and positioning parts, improve contact conditions, and reduce contact stress.
Excessive wear Abrasive wear is in the circulating oil, and the presence of impurities can cause the meshing material to be cut or rubbed off by hard impurities. In order to ensure a certain service life of the friction surface, the hardness of the meshing metal material is at least 30% greater than the hardness of the abrasive.
1) The effect of abrasive size on the wear of the friction surface. It is known from experiments that the wear amount of the friction surface increases proportionally with the increase of the abrasive size, but after reaching a certain size (called the critical size of 70μm ̄80μm), the wear amount remains basically unchanged, because the defects and cracks of the abrasive itself vary with the size. Increase and increase, resulting in reduced tensile strength of the abrasive, easy to break. Therefore, the abrasive size should be strictly controlled within the minimum range (less than or equal to 30μm ~ 40μm). 2) The higher the surface hardness of the rubbing auxiliary material, the more wear-resistant, because the hardness reflects the ability of the worn surface to resist the grinding pressure, but the breaking strength reflects the sensitive property of the material to crack generation and diffusion, and is also important for the wear characteristics of the material. influences.
Missing and maintenance of larger gears