Application Of Heat Treatment Method Before INA Thrust Ball Bearing Installation
Generally, in the cooperation of INA bearings, it is essential to give a suitable interference amount to the bearing ring that rotates under load. Fix the ferrule on the shaft or housing to prevent creep during operation. However, this kind of creep cannot be restricted only by tightening the bearing in the axial direction. Besides, it is usually not necessary to interfere with the ferrule bearing the static load. Moreover, according to the conditions of use, the ease of installation and disassembly, the inner ring and the outer ring is not given an interference amount to cooperate. In this case, lubricate or take other measures for the mating surface where creep is expected.
Everyone knows the heat treatment technology, but what kind of technology is it, and what is it used for? Today we will talk about the application of INA bearing heat treatment technology. For thrust ball bearings, after installation, please do not rush to start using it first, you should make necessary checks to ensure the correct installation and regular use of INA bearings. So is there any right way to check the thrust ball bearings correctly?
After the thrust ball bearing NKI5/16TN is installed, first test a shaft-bearing assembly by hand and observe the following conditions of the thrust ball bearing:
1. Does the rotating system collide or interfere with the fixed parts?
2. The rotation of the rotation system is the ax is stable and flexible without blockage, no looseness, and back and forth movement of the pills;
3. Whether the end face of the inner rings of the thrust ball bearing reliably abuts on the end face of the shaft shoulder, and whether there is a gap between them;
4. Observe whether the lubricant supply or circulation is healthy, whether the gap of the sealing devices is symmetrical, and whether the fastener is loose. With an excessively small amount of interference, the INA bearing is mounted on the shaft, and the inner ring is subjected to load rotation. Harmful sliding in the circumferential directions will occur between the inner circle and the cylinder. The slipping phenomenon of the ferrule, which is called creep, is caused by the shift of the load point in the circumferential direction due to the insufficient amount of interference on the mating surface, and the position of the ferrule relative to the axis or the housing is shifted from the circumferential direction Phenomenon. Once the creep occurs, the mating surface is significantly worn, damaged, or the shell is not uncommon, and the wear powder invades the inside of the bearing, which will cause abnormal heating and vibration.
1.1 The bearing rings and rolling elements are made of GCr15, GCr15SiMn bearing steel, which shall explicitly comply with the requirements of the drawings. Its quality requirements should meet the GB / T18254 standard.
1.2 The heat treatment standards for bearing rings and rolling elements are implemented following the JB / T1255 standard. The uniformity of the hardness of the same part should be within 1HRC.
1.3 The microstructure of the bearing ring martensite after quenching and tempering shall consist of crypto crystals, fine crystalline martensite, uniformly distributed fine residual carbides, a small amount of retained austenite, and a small amount of bainite. After quenching and tempering, Microstructure requirements shall comply with the provisions of JB / T1255.
1.4 P5 and above bearing ring parts must be dimensionally stable.
1. Finished bearing size and rotation accuracy tolerances should meet GB / T307.4, JB / T10336, and relevant requirements of this agreement.
2. Residual magnetic conditions should meet JB / T6641 standard requirements
3. Bearing cleanliness After cleaning the anti-rust finished bearings, the average permissible pollution index of each set of purity is per JB / T7050 standards.
4. Rotation flexibility of the finished bearing After the demagnetization and cleaning of the bearing, and the rotation flexibility check should be performed. The rotation process requires lightness, flexibility, and stability can maintain a specific duration without excessive vibration and sudden braking. There should be no noise during the rotation process, including dust-free noise and the impact of the cage.
5. Roughness. The surface roughness of the bearing parts shall meet the requirements of the drawings, and those not marked on the drawings shall meet the needs of GB / T 307.3.