What kind of bearings are used in heat treatment machines?

Heat treatment machine, heat treatment is currently the highest heating efficiency, the fastest speed, low consumption, energy saving and environmental protection of metal materials.

The waste heat utilization of the combustion furnace has reached a high degree, and the optimization of the burner structure and the strict control of the air-fuel ratio ensure that the NOx and CO are reduced to a minimum under the premise of reasonable combustion. Gas carburizing, carbonitriding and vacuum heat treatment technologies are used to replace salt bath treatment to reduce the pollution of waste salt and CN-containing toxic substances to water sources; Water-soluble synthetic quenching oil is used instead of part of quenching oil, and biodegradable vegetable oil is used instead of part of mineral oil to reduce oil pollution.

Precision heat treatment: precision heat treatment has two meanings: on the one hand, according to the use requirements, materials, and structural dimensions of parts, the use of physical metallurgical knowledge and advanced computer simulation and testing technology to optimize process parameters to achieve the required performance or maximize the potential of materials; On the other hand, it is to fully ensure the stability of the optimized process, so as to achieve very small (or zero) dispersion of product quality and zero distortion of heat treatment.

Clean heat treatment: Waste water, waste gas, waste salt, dust, noise and electromagnetic radiation formed by heat treatment production will cause pollution to the environment. Solving the environmental pollution problem of heat treatment and implementing clean heat treatment (or green heat treatment) is one of the directions for the development of heat treatment technology in developed countries.

In order to reduce the emissions of SO2, CO, CO2, dust and cinder, the use of coal as fuel has been basically eliminated, and the use of heavy oil is also decreasing.

The waste heat utilization of the combustion furnace has reached a high degree, and the optimization of the burner structure and the strict control of the air-fuel ratio ensure that the NOx and CO are reduced to a minimum under the premise of reasonable combustion. Gas carburizing, carbonitriding and vacuum heat treatment technologies are used to replace salt bath treatment to reduce the pollution of waste salt and CN-containing toxic substances to water sources; Water-soluble synthetic quenching oil is used instead of part of quenching oil, and biodegradable vegetable oil is used instead of part of mineral oil to reduce oil pollution.

Precision heat treatment: precision heat treatment has two meanings: on the one hand, according to the use requirements, materials, and structural dimensions of parts, the use of physical metallurgical knowledge and advanced computer simulation and testing technology to optimize process parameters to achieve the required performance or maximize the potential of materials; On the other hand, it is to fully ensure the stability of the optimized process, so as to achieve very small (or zero) dispersion of product quality and zero distortion of heat treatment.

Hello, I think that bearing heat treatment is a key processing process to improve the quality of the inner crack in the bearing, the main purpose is to transform the material structure through heat treatment and improve the mechanical properties of the material.

In this way, the wear resistance and toughness of the bearing can be effectively improved, and the service life of the bearing can be prolonged.

Bearing heat treatment refers to the metal heat treatment process in which the workpiece is heated as a whole and then cooled at an appropriate rate to change its overall mechanical properties. When it comes to heat treatment, we have to mention the industrial "four fires", that is, annealing and normalizing.

Quenching, tempering.

These are the four basic processes in heat treatment, in which quenching and tempering are closely related and often used together, all of which are indispensable.

The general temperature at which the bearing is heated.

It is 80°C 100°C. When the inner diameter of the shaft is greater than 70mm, or the interference is large, the heating method is generally used to expand the inner hole of the bearing and then heat the sleeve. Generally, the bearing is heated to 80°C and up to 100°C.

Exceeding 120°C will cause the bearing to temper, resulting in the reduction of the hardness and accuracy of the bearing ring, and affecting the service life of the bearing. The heating temperature can also be calculated and determined based on the temperature of the assembly environment, the material of the bearing, the diameter of the mating Naomori Genyu, the interference amount and the minimum clearance for hot charging.

1) The application range of GCR15 steel has been expanded, generally the effective wall thickness of the ferrule is less than 12mm when GCR15 steel M is quenched, but due to the strong nitrate cooling ability during BL quenching, the effective wall thickness of the ferrule can be expanded to about 28 mm if stirring, stringing, adding water and other measures are adopted.

2) Stable hardness and good uniformity.

Because the BL transition is a slow process, generally GCR15 steel takes 4H, GCR18Mo steel takes 5H, the ferrule is isothermal in nitrate for a long time, and the surface core structure transformation is carried out almost simultaneously, so the hardness is stable and the uniformity is good, the hardness of GCR15 steel BL after quenching is 59 61HRC, and the uniformity is 1 HRC.

3) Reduce quenching and grinding cracks.

In the production of railway and rolling mill bearings, due to the large size and heavy weight of the ring, the M structure is brittle during oil quenching, and strong cooling measures are often taken to obtain high hardness after quenching, resulting in quenching microcracks; During BL quenching, the BC structure is much tougher than M structure, and the compressive stress of up to -400 -500MPa is formed on the surface, which greatly reduces the quenching crack tendency. During grinding, the surface compressive stress cancels out part of the grinding stress, so that the overall stress level decreases, and the grinding cracks are greatly reduced.

4) The service life of the bearing is improved.

For railways, rolling mill bearings, etc., which bear large impact loads, the main failure modes when used after M quenching are: cracking of the inner ring during assembly, falling off the flange of the outer ring by impact during use, and chipping of the inner ring during use, while the isothermal quenching bearing due to good impact toughness and surface compressive stress, regardless of the cracking of the inner sleeve during assembly, or the loss of the outer sleeve flange during use, the tendency of the inner sleeve to fragment is greatly reduced, and the edge stress concentration of the roller can be reduced. Therefore, the average life and reliability after isothermal quenching are higher than those after M quenching.

Courtesy of Ryoma Bearings.

The bearing steel is heat treated to improve the hardness and wear resistance, which can prolong the service life of the bearing.

In layman's terms, it hardens the material and increases the hardness.

The heat treatment process of bearing steel includes two main links: pre-heat treatment and final heat treatment such as normalizing and annealing. GCR15 steel is a high-carbon chromium bearing steel with less alloy content, good performance, and the most widely used. GCR15 bearing steel has high and uniform hardness, good wear resistance and high contact fatigue performance after heat treatment.

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1) Pre-heat treatment.

Normalizing: Chromium bearing steel normalizing process, the workpiece is kept warm for 40 60min after heat permeation, the cooling needs to be fast, and it is immediately converted to spheroidization annealing after normalizing.

Spheroidized annealing: GCR15 chromium bearing steels are often spheroidized and annealed, and 790 is considered the optimal spheroidizing heating temperature. Before annealing, it needs to be heated to 900 920, and normalized after holding for 2 3 1h.

The holding time depends on the size of the workpiece, the uniformity of the heating furnace, the charging method and the amount of furnace, and the uniformity of the original structure before annealing.

Low-temperature spheroidization annealing is mainly suitable for recrystallization annealing of cold punching balls and cold extrusion rings.

Ordinary spheroidization annealing and isothermal spheroidization annealing are mainly suitable for the annealing of forged ferrules, hot punching balls and transverse forging balls. Chromium bearing steel spheroidization annealing process.

2) Final heat treatment.

Bearing parts: quenching and low-temperature tempering are generally used, the purpose of which is to improve the strength, hardness, wear resistance and fatigue resistance of steel. GCR15 steel quenching temperature is 820 860, and the critical diameter of oil quenching is 25mm.

Generally, oil-cooled quenching is used. The heating and holding time is longer than that of alloy tool steel, and the heating coefficient of the salt bath is taken. Heating coefficient of the air furnace.

160 10 low temperature tempering, tempering time is generally 2 4h.

Precision bearing parts are stable size, after quenching, -60 80 cold treatment should be carried out, the holding time is 2 4h, the parts are restored to room temperature after cold treatment, and tempered within 4h to prevent the parts from cracking.

Residual stresses that are not completely eliminated during low-temperature tempering are redistributed after the grinding process. These two stresses can cause changes in the size of the part and even cracks. For this purpose, another supplementary tempering should be carried out at a tempering temperature of 120 160 and holding for 5 10 hours or more.

Gcr15 heat treatment of tool mold: because this steel is prone to white spot defects, large tool and die heat treatment is easy to crack, the use of slow heating or 690 long-term (greater than 5h) segmented isothermal can reduce the probability of cracking, austenitizing temperature selection 810 10, insulation coefficient a =. Workpieces with a diameter of more than 60 mm need to be quenched with water and oil.