Cylindrical roller bearing ring heat treatment process

Abstract

The invention provides a cylindrical roller bearing ring heat treatment process which comprises the following steps: selecting a material placing mode according to the contact surface of the end surface of a cylindrical roller bearing ring; the surface of the cylindrical roller ferrule is subjected to pre-cleaning for 20-40 min and drying for 10-30 min; carrying out austenitizing treatment, heating to 815-850 DEG C for 70-210 minutes, and carrying out heat preservation; putting the cylindrical roller ferrule into a salt bath medium, cooling to 170-190 DEG C, and quenching for 12-40 minutes; performing air cooling; cleaning for the second time; cryogenic cooling is conducted, and the cylindrical roller ferrule is cooled to 5-10 DEG C; air cooling is conducted on the surface of the cylindrical roller ferrule for 30-80 min, and then cleaning is conducted for 20-40 min; the continuous roller furnace is adopted for heating, heating parameters of the product can be strictly controlled, and a fine martensite structure is formed after quenching at a proper heating temperature, so that the strength and hardness of the product are improved, the service life is prolonged, and the fatigue strength is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of small cylindrical roller bearings, in particular to a heat treatment process for cylindrical roller bearing rings. Background Art

[0002] Small cylindrical roller bearings are a type of bearing widely used in various mechanical fields. Due to their compact structure, strong load-bearing capacity, and small friction torque, they are widely used in automobiles, industrial automation, and medical applications.

[0003] Since some usage scenarios have very high requirements for the dimensional accuracy of bearing rings, the deformation of bearing rings treated by existing heat treatment processes is too large to meet the requirements. How to ensure that the deformation of bearing rings after heat treatment is controllable is an important issue. Summary of the invention

[0004] In view of the above problems, the purpose of this application is to provide a cylindrical roller bearing ring heat treatment process to make it possible.

[0005] In order to achieve some or all of the above purposes or other purposes, the present application provides the following technical solution: a heat treatment process for a cylindrical roller bearing ring, the specific steps of which include: S1. Select the material swinging method according to the contact surface of the cylindrical roller ring end face. When the contact surface of the cylindrical roller ring end face is ≤25mm, the upper and lower end faces are stacked without padding. When the contact surface of the cylindrical roller ring end face is greater than 25mm, the middle padding method is adopted. S2. Pre-clean the surface of the cylindrical roller ring for 20-40 minutes and dry it for 10-30 minutes; S3, heating to 815°C-850°C for 70-210min and keeping warm; S4. Place the cylindrical roller ring into the salt bath medium, cool to 170°C-190°C, and quench for 12min-40min; S5, air cooling; S6, secondary cleaning; S7, deep cooling, cooling the cylindrical roller ring to 5℃-10℃, so that austenite continues to transform into martensite; S8, tempering at 190℃-220℃, keeping warm for 8-10h, so that the quenched martensite is transformed into tempered martensite and the residual austenite is eliminated; S9. Air cool the surface of the cylindrical roller ring for 30-80 minutes, and then clean it for 20-40 minutes.

[0006] Furthermore, the specific method of step S3 includes: using a continuous roller furnace heating method.

[0007] Furthermore, the specific method of step S3 includes: carbon potential 0.45%-0.70%.

[0008] Furthermore, the specific method of step S3 includes: placing the cylindrical roller ring into a roller heating furnace, introducing nitrogen at a flow rate of 10-15m³ / h to exhaust the air in the heating furnace.

[0009] Furthermore, the specific method of step S3 includes: introducing propane into the heating furnace at a flow rate of 0.6-1.2 L / h.

[0010] Furthermore, the specific method of step S3 includes: front ventilation chamber purge nitrogen: 6-10m³ / h, rear ventilation chamber purge nitrogen: 6-10m³ / h, oxygen probe purge gas: 160-260 L / h.

[0011] Furthermore, the cylindrical roller bearing ring has specifications of NU238M.01, a diameter of 340 mm, a width of 55 mm, and a wall thickness of 20.5 mm.

[0012] Furthermore, the cylindrical roller bearing ring is made of GCr15SiMn material.

[0013] Furthermore, the specific steps of the heat treatment process of the cylindrical roller bearing ring include: S1. Select the material swinging method according to the contact surface of the cylindrical roller ring end face. When the contact surface of the cylindrical roller ring end face is ≤25mm, the upper and lower end faces are stacked without padding. When the contact surface of the cylindrical roller ring end face is greater than 25mm, the middle padding method is adopted. S2, drying the surface of the cylindrical roller ring for 25 minutes; S3, austenitizing treatment is carried out and heated to 830℃ for 120min; carbon potential is 0.60%; nitrogen is introduced at a flow rate of 12m³ / h; propane is introduced into the heating furnace at a flow rate of 1.0 L / h; nitrogen purge in the front ventilation chamber: 8m³ / h, nitrogen purge in the rear ventilation chamber: 8m³ / h, oxygen probe purge gas: 200 L / h; S4. Place the cylindrical roller ring into the salt bath medium, cool to 175°C, and quench for 20 minutes; S5, air cooling; S6, secondary cleaning; S7, deep cooling, cooling the cylindrical roller ring to 7°C; S8, tempering at 200℃, keeping warm for 8h; S9. Air cool the surface of the cylindrical roller ring for 30 minutes and then clean it for 20 minutes.

[0014] Compared with the prior art, the beneficial effects of the present invention are: this kind of swinging material can effectively reduce the deformation and taper caused by uneven heating of the material mesh; it adopts continuous roller furnace heating, strictly controls the heating parameters of the product, and selects the appropriate heating temperature to form a fine martensitic structure after quenching, so as to improve the strength and hardness of the product, and improve the service life and fatigue strength. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is the process curve of the present invention; Figure 2 It is a schematic diagram of the structure of a cylindrical roller bearing ring. DETAILED DESCRIPTION

[0016] In order to make the structure and function of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0017] See attached Figure 1-2 , the heat treatment process of cylindrical roller bearing rings, the specific steps include: S1. Select the material swinging method according to the contact surface of the cylindrical roller ring end face. When the contact surface of the cylindrical roller ring end face is ≤25mm, the upper and lower end faces are stacked without mesh padding. When the contact surface of the cylindrical roller ring end face is greater than 25mm, the middle mesh padding method is used. This material swinging method can effectively reduce the deformation and taper caused by uneven material mesh and uneven heating. S2. Pre-clean the surface of the cylindrical roller ring for 20-40 minutes and dry it for 10-30 minutes; S3, heating to 815°C-850°C for 70-210min and keeping warm; S4. Place the cylindrical roller ring into the salt bath medium, cool to 170°C-190°C, and quench for 12min-40min; S5, air cooling; S6, secondary cleaning; S7, deep cooling, cooling the cylindrical roller ring to 5℃-10℃, so that austenite continues to transform into martensite; S8, tempering at 190℃-220℃, keeping warm for 8-10h, so that the quenched martensite is transformed into tempered martensite and the residual austenite is eliminated; S9. Air cool the surface of the cylindrical roller ring for 30-80 minutes, and then clean it for 20-40 minutes.

[0018] The specific method of step S3 includes: using a continuous roller furnace heating method; strictly controlling the heating parameters of the product, selecting an appropriate heating temperature to form a fine martensitic structure after quenching, so as to improve the strength and hardness of the product, and improve the service life and fatigue strength.

[0019] The specific method of step S3 includes: carbon potential 0.45%-0.70%.

[0020] The specific method of step S3 includes: placing the cylindrical roller ring into a roller heating furnace, introducing nitrogen at a flow rate of 10-15m³ / h to exhaust the air in the heating furnace.

[0021] The specific method of step S3 includes: introducing propane into the heating furnace at a flow rate of 0.6-1.2 L / h.

[0022] The specific method of step S3 includes: front ventilation chamber purge nitrogen: 6-10m³ / h, rear ventilation chamber purge nitrogen: 6-10m³ / h, oxygen probe purge gas: 160-260 L / h.

[0023] The cylindrical roller bearing ring specifications are NU238M.01, diameter 340mm, width 55mm, and wall thickness 20.5mm.

[0024] Preferably, the steel grade of the small cylindrical roller bearing is GCr15SiMn, which has relatively good hardenability. During the processing, the contact surface of the end face of the bearing is less than 25mm when the material is swung. The original swinging method is to swing the material with an intermediate pad mesh. The deformation of the bearing exceeds 50%, and if the material tray is uneven, there is a risk of bending of the end face. For this kind of small cylindrical roller ring, the end face reserve is generally not as large as that of the small tapered roller ring. Once the product is bent too much, there is a risk of scrapping. It is now changed to direct stacking with end face contact. It has been verified that the hardenability of the area where the products are stacked will not change. The test results all meet the technical requirements of the drawings. At the same time, the bending of the product is also controlled, which greatly reduces the scrapping of products caused by uneven material trays.

[0025] The specific steps of the heat treatment process for cylindrical roller bearing rings include: S1. Select the material swinging method according to the contact surface of the cylindrical roller ring end face. When the contact surface of the cylindrical roller ring end face is ≤25mm, the upper and lower end faces are stacked without padding. When the contact surface of the cylindrical roller ring end face is greater than 25mm, the middle padding method is adopted. S2, drying the surface of the cylindrical roller ring for 25 minutes; S3, austenitizing treatment is carried out and heated to 830℃ for 120min; carbon potential is 0.60%; nitrogen is introduced at a flow rate of 12m³ / h; propane is introduced into the heating furnace at a flow rate of 1.0 L / h; nitrogen purge in the front ventilation chamber: 8m³ / h, nitrogen purge in the rear ventilation chamber: 8m³ / h, oxygen probe purge gas: 200 L / h; S4. Place the cylindrical roller ring into the salt bath medium, cool to 175°C, and quench for 20 minutes; S5, air cooling; S6, secondary cleaning; S7, deep cooling, cooling the cylindrical roller ring to 7°C; S8, tempering at 200℃, keeping warm for 8h; S9. Air cool the surface of the cylindrical roller ring for 30 minutes and then clean it for 20 minutes.

[0026] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. Cylindrical roller bearing ring heat treatment process, characterized by: The specific steps include: S1. Select the material swinging method according to the contact surface of the cylindrical roller ring end face. When the contact surface of the cylindrical roller ring end face is ≤25mm, the upper and lower end faces are stacked without padding. When the contact surface of the cylindrical roller ring end face is greater than 25mm, the middle padding method is adopted. S2. Pre-clean the surface of the cylindrical roller ring for 20-40 minutes and dry it for 10-30 minutes; S3, heating to 815°C-850°C for 70-210min and keeping warm; S4. Place the cylindrical roller ring into the salt bath medium, cool to 170°C-190°C, and quench for 12min-40min; S5, air cooling; S6, secondary cleaning; S7, deep cooling, cooling the cylindrical roller ring to 5℃-10℃, so that austenite continues to transform into martensite; S8, tempering at 190℃-220℃, keeping warm for 8-10h, so that the quenched martensite is transformed into tempered martensite and the residual austenite is eliminated; S9. Air cool the surface of the cylindrical roller ring for 30-80 minutes, and then clean it for 20-40 minutes.

2. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The specific method of step S3 includes: using a continuous roller furnace heating method.

3. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The specific method of step S3 includes: carbon potential 0.45%-0.70%.

4. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The specific method of step S3 includes: placing the cylindrical roller ring into a roller heating furnace, introducing nitrogen at a flow rate of 10-15m³ / h to exhaust the air in the heating furnace.

5. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The specific method of step S3 includes: introducing propane into the heating furnace at a flow rate of 0.6-1.2 L / h.

6. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The specific method of step S3 includes: front ventilation chamber purge nitrogen: 6-10m³ / h, rear ventilation chamber purge nitrogen: 6-10m³ / h, oxygen probe purge gas: 160-260 L / h.

7. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The cylindrical roller bearing ring specifications are NU238M.01, diameter 340mm, width 55mm, and wall thickness 20.5mm.

8. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The cylindrical roller bearing ring is made of GCr15SiMn material.

9. The cylindrical roller bearing ring heat treatment process according to claim 1, characterized in that: The specific steps include: S1. Select the material swinging method according to the contact surface of the cylindrical roller ring end face. When the contact surface of the cylindrical roller ring end face is ≤25mm, the upper and lower end faces are stacked without padding. When the contact surface of the cylindrical roller ring end face is greater than 25mm, the middle padding method is adopted. S2, drying the surface of the cylindrical roller ring for 25 minutes; S3, carry out austenitizing treatment and heat to 830℃ for 120min; carbon potential 0.60%; put the cylindrical roller ring into the roller heating furnace, and introduce nitrogen at a flow rate of 12m³ / h; introduce propane into the heating furnace at a flow rate of 1.0 L / h; purge nitrogen in the front ventilation chamber: 8m³ / h, purge nitrogen in the rear ventilation chamber: 8m³ / h, and purge gas for the oxygen probe: 200 L / h; S4. Place the cylindrical roller ring into the salt bath medium, cool to 175°C, and quench for 20 minutes; S5, air cooling; S6, secondary cleaning; S7, deep cooling, cooling the cylindrical roller ring to 7°C; S8, tempering at 200℃, keeping warm for 8h; S9. Air cool the surface of the cylindrical roller ring for 30 minutes and then clean it for 20 minutes.

Images