Bearing processing heat treatment process and technology

Treatment History
(1) Clean the heat treatment
The formation of heat production of wastewater, waste gas, waste salt, dust, noise and electromagnetic radiation Dengjun causes environmental pollution. Solve the heat problem of environmental pollution, the implementation of clean heat (or green heat treatment) is a technology developed in the direction of heat treatment. In order to reduce SO2, CO, CO2, emissions of dust and cinders, has basically put an end to the use of coal as fuel, the use of heavy oil less and less in favor of the majority of light oil, natural gas is still the best fuel.
Steel Linear Bearing  Large Linear Bearings  Linear Ball Bearings  Precision Linear Bearing
Waste heat from the burner has reached a high level of use of the burner structure optimization and air - fuel ratio, combustion strict control to ensure reasonable under the premise of the NOX and CO decreased to a minimum; use of gas carburizing, carbonitriding and vacuum heat treatment technology alternatives to reduce the salt treatment with CN-waste salt and toxic contamination of water sources; use of synthetic water-soluble quenching oil instead of part of the quenching oil, the use of biodegradable vegetable oil instead of part of mineral oil to reduce oil pollution.
(2) Precision Heat Treatment
Precision heat treatment has two meanings: one is based on requirements of parts, materials, structure size, the use of physical metallurgy knowledge and advanced computer simulation and testing technology to optimize process parameters to achieve the required performance or to maximize the material potential; the other hand, fully guarantee the stability of optimization process to achieve product quality and dispersion of small (or zero), and heat distortion is zero.
(3) energy-saving heat
Scientific production and energy management is the most efficient use of energy has the potential factors, the establishment of specialized treatment plant to ensure full capacity, the ability to give full play equipment, scientific management of choice. Energy structure in the heat treatment, the preferred choice of primary energy; full use of waste heat, waste heat; with low energy consumption, short cycle process instead of a long cycle, energy-consuming process and so on.
(4) Heat a small non-oxidation
Alternative protective atmosphere heating by the use of heat to the precise control of oxidation of the atmosphere carbon potential, nitrogen potential of the controlled atmosphere heating, heat treatment to improve the performance of parts, heat treatment defects such as removal, crack greatly reduced, leaving the finishing heat treatment reduced to improve the utilization of materials and machining efficiency. Vacuum plus hot quenching, vacuum or low pressure carburizing, nitriding, Nitrocarburizing and boron penetration can significantly improve quality, reduce distortion and improve life.
Effect of heat treatment technology
(1) expanded the scope of application GCr15 steel, generally M quenching GCr15 steel rings 12mm wall thickness less effective, but the nitrate BL quenching cooling capacity, the use of a stirring, string action, water and other measures, ring effective thickness can be extended to 28mm or so.
(2) hardness and stability, good uniformity
Because change is a slow process of BL, the general GCr15 steel to be 4h, GCr18Mo steel to be 5h, ring in the nitrate in the long isothermal, Ministry of the surface of the heart changes in almost the same time, so the hardness and stability, good uniformity, the general BL GCr15 steel after quenching hardness 59 ~ 61HRC, uniformity ≤ 1HRC, not as quenching ring appeared slightly larger wall thickness of low hardness, soft spots, and poor uniformity.
(3) to reduce quenching, grinding cracks
In the railways, rolling mill bearing production, due to large ring size and weight, oil quenching M tissue brittleness, in order to obtain high hardness after quenching cooling measures often take strong, resulting in quenching cracks; and BL quenching, due to BL is much better organized than the M tissue toughness, while the surface of up to -400 ~-500MPa compressive stress, which greatly reduces the tendency of quenching cracks; in the surface grinding stress partly offset by a grinding stress, and the overall stress level down, greatly reducing the grinding cracks.
(4) bearing service life
Withstand large impact loads for the railway, rolling mill bearings, hardened by the M main failure mode when used as follows: when the inner sleeve assembly cracking, use the process off by the impact of outer wall blocks, inner ring fragmentation, while bearing Austempering the impact toughness, and surface stress, both sets of cracks within the assembly, or the use of the process out of the block wall jacket, inner sleeve fracture orientation greatly reduced, and the roller can reduce the edge stress concentration. Therefore, the isothermal quenching, after quenching than the average life span of M and increased reliability.