How is the blackening treatment of the slewing bearing done?
How is the blackening treatment of the slewing bearing done?
1. How to deal with blackening of slewing bearings
There are many methods used for anti-rust treatment of metal materials, including alkaline organic chemical oxidation, medium alkali oxidation, high temperature gas oxidation and chemical oxidation. Among them, the blackening treatment is a kind of surface oxidation treatment. The specific method is to put the bearing into thick alkali and oxide, and after a certain temperature of heating and oxidation, the bearing surface will form a uniform layer. The tight ferric oxide film is firmly integrated with the original metal material and has an anti-corrosion effect. Because ferric oxide turns black, this type of anti-rust treatment solution is also called blackening treatment. Of course, due to the influence of various factors during use, the colors of the oxidation film also include blue, brown-red and brown. The resulting oxidation film is beautiful in color, flexible, and the film is generally 0.5-1.5um thick. It does not affect the overall size and precision of the bearing. At the same time, it has the effect of eliminating the deformation that occurs after the heat treatment process. certain efficacy.
2. Production process of blackening treatment of slewing bearings
For blackening treatment of slewing bearings made of high carbon steel, low carbon steel, medium carbon steel, carbon steel and steel castings, you should follow the preparation work → degreasing → flushing → pickling and passivation → flushing → blackening → flushing → The production process of oil immersion→drying→testing. The actual production process is as follows:
（1）Check the bearing quality: Before carrying out the blackening process, the bearing quality must be checked first. For parts with decorative art requirements, the surface roughness should be less than Ral.6um, generally it should be Ra3.2um. There should be no cracks, bumps, defects or metal coatings on the surface. Severe rust on the surface and thick oxide scale that cannot be removed will affect the blackening process.
（2）Cleaning and degreasing: To remove oil stains on the bearing surface, the bearing must be placed in a solution of U7684 metal lotion with a concentration of 3%-5%, and soaked at a temperature of 70-100°C for 10-30 minutes. According to The degree of oil stain determines the time, and then washed with water until the oil stains and water solution on the workpiece are removed.
（3）Pickling, passivation and anti-rust treatment: The rust and oxide scale on the bearing surface must be removed before blackening, but the bearing surface cannot be corroded, so the pickling and passivation time of the bearing should be controlled, using 60%u6D53 Hydrochloric acid solution with a certain concentration, soak for 5-10 minutes. After soaking, use fluid tap water to clean to remove the remaining hydrochloric acid solution on the bearing surface.
（4）Blackening treatment: High-temperature soaking, place the bearing in a blackening liquid containing sodium hydroxide solution and sodium nitrite as the main components. The temperature of the solution is controlled at 125-155°C, and soaked in two times. After 8-10 minutes, take it off and blow dry, observe the surface coloring, and then soak it in the blackening liquid for 8-10 minutes for secondary blackening. Remove it again, observe the coloring, and adjust the amount, concentration, and temperature of the substance in time.
（5）Clean the soap stock: Put the blackened bearing into the soap stock solution to wash the soap stock. The temperature should be controlled at 20-50°C. Soak for 3-5 minutes, rinse with cold water and blow dry.
（6）Skeleton seal sealed type: soak the mechanical lubricating oil for ten minutes after using anti-rust agent. The temperature of the skeleton seal is used according to the standards of refined oil. Generally, the heating temperature when using general mechanical lubricating oil is around 105-120℃. , the skeleton sealing time is 2-5 minutes, and it can be dehydrated after taking it out.
（7）Appearance inspection: Carry out appearance inspection of the blackening color uniformity of the bearing. Generally, the thickness of the protective film after blackening is 0.6-1.5um.
