阅读说明：本技术 高精度长寿命滚动体热处理渗碳工艺 (High-precision long-life rolling body heat treatment carburizing process ) 是由 马林 沈达恺 张庆忠 于 2021-06-22 设计创作，主要内容包括：本发明涉及轴承滚子热处理领域,尤其涉及一种高精度长寿命滚动体热处理渗碳工艺艺。将称好滚子输送到履带式超声波清洗机中清洗；在烘干装置中烘干后,后续经过表面渗碳处理；热处理步骤制备而成。经过本发明工艺处理后的滚子,其耐磨性、耐腐蚀性、冲击韧性、经年变化率均得到大幅提高,经过冷处理的渗碳滚子,可以大幅提高轴承零件的精度,同时保证轴承在长期使用状态下或存放状态下无论是高温或低温状态下,滚子尺寸都不会发生任何变化,这样才能保证滚动体经年变化率。很好的满足了国内外高端轴承客户对高精度,长寿命,低噪音的滚子质量需求。(The invention relates to the field of bearing roller heat treatment, in particular to a heat treatment carburizing process for a rolling body with high precision and long service life. Conveying the weighed roller to a crawler-type ultrasonic cleaning machine for cleaning; drying in a drying device, and then performing surface carburization treatment; and (3) a heat treatment step. The roller treated by the process has greatly improved wear resistance, corrosion resistance, impact toughness and annual change rate, the carburized roller subjected to cold treatment can greatly improve the precision of bearing parts, and simultaneously the size of the roller can not be changed in a long-term use state or a storage state no matter in a high-temperature or low-temperature state, so that the annual change rate of a rolling body can be ensured. The roller quality requirements of domestic and foreign high-end bearing customers on high precision, long service life and low noise are well met.)

1. A heat treatment carburizing process for a rolling body with high precision and long service life is characterized in that: the process comprises the following steps:

1) and workpiece pretreatment: firstly, a roller to be treated is arranged in a special material frame for roller quenching and tempering, then the roller is weighed by a weighing device, the weighed roller is conveyed to a cleaning device for cleaning, and after cleaning, the roller is dried by a circulating hot air drying device;

2) preheating the workpiece: preheating the dried roller in a heat treatment furnace, heating the roller to 450-500 ℃, and preserving heat for 1.5-2.5 hours;

3) carburizing and quenching the workpiece: heating the preheated and heat-preserved workpiece to 900-1000 ℃, introducing acetone, methanol and a promoter, controlling the flow rate to 200-220 ml/min, controlling the carbon potential to be 1.10 +/-0.05%, preserving heat for 3-4 hours, adjusting the carbon potential to be 0.95 +/-0.05%, adjusting the flow rate of acetone and methanol to be 150-170 ml/min, preserving heat for 50-70 minutes, reducing the carbon potential to be 0.85 +/-0.05%, reducing the temperature to 780-850 ℃, preserving heat for 1-2 hours, and then quenching, wherein the salt temperature is 170 +/-5 ℃;

4) cooling the workpiece: cooling the roller subjected to carburizing and quenching in the step 3 in a cooling device, wherein the cooling temperature is controlled to be between 10 ℃ below zero and 15 ℃ below zero for 10 to 20 min;

5) cleaning a workpiece: cleaning and spraying water on the roller cooled in the step 4 by using a cleaning device to remove the residual nitrate on the surface of the roller;

6) pre-tempering a workpiece: placing the roller cleaned in the step 5 in equipment with circulating moving air for pre-tempering, wherein the pre-tempering temperature is 130 +/-5 ℃, and the time is 2.5-3.5 hours;

7) and (3) secondary tempering of the workpiece: conveying the pre-tempered roller into high-temperature tempering equipment with circulating moving air in a furnace for secondary tempering, wherein the tempering temperature is 250 +/-5 ℃, and the tempering time is 4-5 hours;

8) workpiece detection: the hardness grain difference is less than 0.5HRC, the hardness batch difference is less than 1.0HRC, and the retained austenite on the surface of the roller is less than or equal to 2 percent.

2. The heat treatment carburizing process for the high-precision long-life rolling body according to claim 1, characterized in that: the sum of the weight of the roller and the weight of the material frame in the step 1 is less than or equal to 180 kg.

3. The heat treatment carburizing process for the high-precision long-life rolling body according to claim 1, characterized in that: the roller to be treated is a tapered roller or a cylindrical roller, and the diameter of each tapered roller or cylindrical roller is larger than 50 mm.

4. The heat treatment carburizing process for the high-precision long-life rolling body according to claim 1, characterized in that: in the step 1, the cleaning device is a crawler-type ultrasonic cleaning machine, and an environment-friendly cleaning agent is used for cleaning in the cleaning process.

5. The heat treatment carburizing process for the high-precision long-life rolling body according to claim 1, characterized in that: and 4, the cooling device is a crawler-type cold water tank.

6. The heat treatment carburizing process for the high-precision long-life rolling body according to claim 1, characterized in that: the cleaning device in the step 5 is a high-pressure type spraying crawler belt type cleaning machine, and an environment-friendly cleaning agent is used for cleaning in the cleaning process.

Technical Field

The invention relates to the field of bearing roller heat treatment, in particular to a heat treatment carburizing process for a rolling body with high precision and long service life.

Background

At present, the carburizing roller is mainly applied to offshore wind power generation, a rotary support bearing and a large engineering mechanical shield machine, the application range is wide, the price of the carburizing roller is 3-4 times that of a non-carburizing roller, the carburizing roller can completely replace an imported roller, and the market prospect is wide.

Because different use environments and different requirements of domestic and foreign customers on a roller effective hardened layer (CHD), the roller heat treatment carburization has the following difficulties:

1. the carburization initial carburization speed is high, as the depth of the hardened layer becomes thicker and the time is longer, the effective hardened layer (CHD will become slower; 2. the influence of carbon black produced by carburization on workshop production environment; 3. the selection range of the carburizing agent (with less impurities, especially with low sulfur content (normally less than 0.04%) is narrower; and 4. the roller carburization uniformity control difficulty is large when the depth of the effective hardened layer (CHD) is more than 3.5 mm.

Disclosure of Invention

In order to solve the technical problems, the invention provides a high-precision long-life roller heat treatment carburizing process which is ingenious in design and complete in process.

The technical scheme provided by the invention is as follows: 1. a heat treatment carburizing process for a high-precision long-life rolling body comprises the following steps:

1) and workpiece pretreatment: firstly, a roller to be treated is loaded into a special material frame for roller quenching and tempering, then the roller is weighed by a weighing device, the weighed roller is conveyed into a cleaning device for cleaning, and after cleaning, the roller is dried by a circulating hot air drying device.

2) Preheating the workpiece: and (3) preheating the dried roller in a heat treatment furnace, heating the roller to 450-500 ℃, and preserving heat for 1.5-2.5 hours.

3) Carburizing and quenching the workpiece: heating the preheated and heat-preserved workpiece to 900-1000 ℃, introducing acetone, methanol and a promoter, controlling the flow rate to 200-220 ml/min, controlling the carbon potential to be 1.10 +/-0.05%, preserving heat for 3-4 hours, adjusting the carbon potential to be 0.95 +/-0.05%, adjusting the flow rate of acetone and methanol to be 150-170 ml/min, preserving heat for 50-70 minutes, reducing the carbon potential to be 0.85 +/-0.05%, reducing the temperature to 780-850 ℃, preserving heat for 1-2 hours, and then quenching, wherein the salt temperature is 170 +/-5 ℃.

4) Cooling the workpiece: and (4) cooling the roller subjected to carburizing and quenching in the step (3) in a cooling device, wherein the cooling temperature is controlled to be between 10 ℃ below zero and 15 ℃ below zero for 10 to 20 min.

5) Cleaning a workpiece: and (4) cleaning and spraying water on the roller cooled in the step (4) by using a cleaning device to remove the residual nitrate on the surface of the roller.

6) Pre-tempering a workpiece: and (3) placing the roller cleaned in the step (5) in equipment with circulating air for pre-tempering, wherein the pre-tempering temperature is 130 +/-5 ℃, and the time is 2.5-3.5 hours.

7) And (3) secondary tempering of the workpiece: and (3) conveying the pre-tempered roller into high-temperature tempering equipment with circulating moving air in a furnace for secondary tempering, wherein the tempering temperature is 250 +/-5 ℃, and the tempering time is 4-5 hours.

8) Workpiece detection: the hardness grain difference is less than 0.5HRC, the hardness batch difference is less than 1.0HRC, and the retained austenite on the surface of the roller is less than or equal to 2 percent.

Further optimization and improvement of the scheme are as follows: the sum of the weight of the roller and the weight of the material frame in the step 1 is less than or equal to 180 kg.

Further optimization and improvement of the scheme are as follows: the roller to be treated is a tapered roller or a cylindrical roller, and the diameter of each tapered roller or cylindrical roller is larger than 50 mm.

Further optimization and improvement of the scheme are as follows: in the step 1, the cleaning device is a crawler-type ultrasonic cleaning machine, and an environment-friendly cleaning agent is used for cleaning in the cleaning process.

Further optimization and improvement of the scheme are as follows: and 4, the cooling device is a crawler-type cold water tank.

Further optimization and improvement of the scheme are as follows: the cleaning device in the step 5 is a high-pressure type spraying crawler belt type cleaning machine, and an environment-friendly cleaning agent is used for cleaning in the cleaning process.

Compared with the prior art, the invention has the following beneficial effects:

1. the invention adopts an ultrasonic cleaning mode of automatically weighing each material frame, has uniform feeding and can fully ensure the cleaning effect of each roller. The cleaning mode ensures that the surface of the roller after being cleaned is free from iron powder adhesion and the surface of the roller after being dried is clean, no residual moisture enters an austenitizing heating furnace, and the possibility of decarburization of the roller is reduced. The weighing equipment used before the roller is cleaned is Fengdong electronic weighing equipment; the weighing precision is controlled to be +/-0.5 Kg of a set value; the crawler-type ultrasonic cleaning machine in the step 1 is ultrasonic cleaning belt drying and heating equipment of an FBQ (fiber bulk Container) (w) 3-9090120 type multi-purpose furnace salt bath automatic production line of Toyoto company; the salt bath equipment in the step 3 is an FBQ (salt bath) 3-9090120 type multi-purpose furnace salt bath automatic production line in Toyoto.

2. The roller is preheated before entering the carburizing furnace, so that the surface stress of the material and the surface stress of the material caused by turning can be effectively eliminated, the risk of cracks caused by overlarge stress during roller carburizing and quenching is reduced, the traditional carburizing process of exhausting, forced infiltration, diffusion and cooling is adjusted to the existing carburizing process of forced infiltration, diffusion and cooling, the technological link of exhausting is reduced, and the production cost is saved.

2. After the roller is carburized and quenched, because the phase transformation from an austenite structure to a martensite has larger stress, and in addition, the heat treatment inside the carburized roller has larger heat stress, and in addition, because the hardness of the roller is increased due to the transformation from the residual austenite to the martensite after the cold treatment, the roller stress is increased, so the carburized roller after the cold treatment needs to be subjected to one-time pre-tempering, the pre-tempering can achieve the aim of pre-dehydrogenation while removing the stress generated by the roller due to the phase transformation and the heat treatment residual stress and the stress of the residual austenite transformed to the martensite after the cold treatment, and the service performance of the carburized roller is greatly improved after the hydrogen is removed; the pre-tempering and the high-temperature tempering of the carburized roller can meet the requirement that the residual austenite is less than 2 percent (the national standard is less than or equal to 15 percent), the carburized roller is tempered twice, the dimensional stability of the roller after carburization can be better, the hardness difference between the core part and the carburized layer is controlled within 3HRC, the service life of the roller is greatly prolonged, and the special quality requirements of high precision, long service life, higher dimensional stability, impact resistance and the like of the roller on high-speed railways and urban subway are ensured.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

Example 1:

a heat treatment carburizing process for a high-precision long-life rolling body comprises the following steps:

1) and workpiece pretreatment: firstly, a roller to be treated is loaded into a special material frame for roller quenching and tempering, then the roller is weighed by a weighing device, the weighed roller is conveyed into a cleaning device for cleaning, and after cleaning, the roller is dried by a circulating hot air drying device.

2) Preheating the workpiece: and (3) preheating the dried roller in a heat treatment furnace, heating the roller to 450 ℃, and preserving heat for 2.5 hours.

3) Carburizing and quenching the workpiece: heating the preheated and heat-preserved workpiece to 900 ℃, introducing acetone, methanol and a promoter, controlling the flow rate to be 220ml/min and the carbon potential to be 1.05%, adjusting the carbon potential to be 1.00% and the acetone and methanol flow rate to be 170 ml/min after heat preservation for 4 hours, reducing the carbon potential to be 0.90% after heat preservation for 70 minutes, reducing the temperature to 850 ℃, quenching after heat preservation for 2 hours, and controlling the salt temperature to be 175 ℃.

4) Cooling the workpiece: and (4) cooling the roller subjected to carburizing and quenching in the step (3) in a cooling device, wherein the cooling temperature is controlled to be-15 ℃ for 10 minutes.

5) Cleaning a workpiece: and (4) cleaning and spraying water on the roller cooled in the step (4) by using a cleaning device to remove the residual nitrate on the surface of the roller.

6) Pre-tempering a workpiece: and (3) placing the roller cleaned in the step (5) in equipment with circulating air for pre-tempering, wherein the pre-tempering temperature is 125 ℃, and the time is 3.5 hours.

7) And (3) secondary tempering of the workpiece: and (3) conveying the roller subjected to pre-tempering into high-temperature tempering equipment with circulating moving air in a furnace for secondary tempering, wherein the tempering temperature is 245 ℃, and the tempering time is 5 hours.

8) Workpiece detection: the hardness grain difference is 0.2HRC, the hardness batch difference is 0.8HRC, and the retained austenite on the surface of the roller is 1.2%.

The performance test of the roller processed by the steps is shown in the table one:

table one:

example 2:

a heat treatment carburizing process for a high-precision long-life rolling body comprises the following steps:

1) and workpiece pretreatment: firstly, a roller to be treated is loaded into a special material frame for roller quenching and tempering, then the roller is weighed by a weighing device, the weighed roller is conveyed into a cleaning device for cleaning, and after cleaning, the roller is dried by a circulating hot air drying device.

2) Preheating the workpiece: and (3) preheating the dried roller in a heat treatment furnace, heating the roller to 470 ℃, and preserving heat for 2 hours.

3) Carburizing and quenching the workpiece: heating the preheated and heat-preserved workpiece to 935 ℃, introducing acetone, methanol and a promoter, controlling the flow rate to be 210ml/min and the carbon potential to be 1.10%, adjusting the carbon potential to be 0.95% after heat preservation for 3.5 hours, adjusting the flow rate of acetone and methanol to be 160 ml/min, reducing the carbon potential to be 0.85% after heat preservation for 60 minutes, reducing the temperature to 800 ℃, quenching after heat preservation for 1.5 hours, and controlling the salt temperature to be 170 ℃.

4) Cooling the workpiece: and (4) cooling the roller subjected to carburizing and quenching in the step (3) in a cooling device, wherein the cooling temperature is controlled to be-12 ℃ for 15 minutes.

5) Cleaning a workpiece: and (4) cleaning and spraying water on the roller cooled in the step (4) by using a cleaning device to remove the residual nitrate on the surface of the roller.

6) Pre-tempering a workpiece: and (3) placing the roller cleaned in the step (5) in equipment with circulating air for pre-tempering, wherein the pre-tempering temperature is 130 ℃, and the time is 3 hours.

7) And (3) secondary tempering of the workpiece: and (3) conveying the roller subjected to pre-tempering into high-temperature tempering equipment with circulating moving air in a furnace for secondary tempering, wherein the tempering temperature is 250 ℃, and the tempering time is 4.5 hours.

8) Workpiece detection: the hardness grain difference is 0.22HRC, the hardness batch difference is 0.6HRC, and the retained austenite on the surface of the roller is 0.8%.

The performance test of the roller processed by the above steps is shown in table two:

table two:

example 3:

1) and workpiece pretreatment: firstly, a roller to be treated is loaded into a special material frame for roller quenching and tempering, then the roller is weighed by a weighing device, the weighed roller is conveyed into a cleaning device for cleaning, and after cleaning, the roller is dried by a circulating hot air drying device.

2) Preheating the workpiece: and (3) preheating the dried roller in a heat treatment furnace, heating the roller to 500 ℃, and preserving heat for 1.5 hours.

3) Carburizing and quenching the workpiece: heating the preheated and heat-preserved workpiece to 1000 ℃, introducing acetone, methanol and a promoter, controlling the flow rate to be 220ml/min and the carbon potential to be 1.05%, adjusting the carbon potential to be 0.905% and the acetone and methanol flow rate to be 150ml/min after heat preservation for 3 hours, reducing the carbon potential to be 0.80% after heat preservation for 50 minutes, reducing the temperature to 850 ℃, quenching after heat preservation for 1 hour, and controlling the salt temperature to be 165 ℃.

4) Cooling the workpiece: and (4) cooling the roller subjected to carburizing and quenching in the step (3) in a cooling device, wherein the cooling temperature is controlled to be-10 ℃ and the time is 20 min.

5) Cleaning a workpiece: and (4) cleaning and spraying water on the roller cooled in the step (4) by using a cleaning device to remove the residual nitrate on the surface of the roller.

6) Pre-tempering a workpiece: and (3) placing the roller cleaned in the step (5) in equipment with circulating air for pre-tempering, wherein the pre-tempering temperature is 125 ℃, and the time is 3.5 hours.

7) And (3) secondary tempering of the workpiece: and (3) conveying the roller subjected to pre-tempering into high-temperature tempering equipment with circulating moving air in a furnace for secondary tempering, wherein the tempering temperature is 245 ℃, and the tempering time is 5 hours.

8) Workpiece detection: the hardness grain difference is 0.4HRC, the hardness batch difference is 0.7HRC, and the retained austenite on the surface of the roller is 0.4%.

The roller performance test after the above steps is shown in table three:

table three:

the contents of the three tables show that after the roller is treated by the method, particularly after the roller is subjected to pre-tempering and high-temperature tempering, the residual austenite can be controlled to be less than or equal to 2%, the wear resistance, the corrosion resistance, the impact toughness and the annual change rate of the roller are greatly improved, the precision of bearing parts can be greatly improved by the carburized roller subjected to cold treatment, the size of the roller can not be changed in a high-temperature environment or a low-temperature environment in a long-term use state or a storage state of the bearing, and the annual change rate of the roller is ensured.

The embodiments of the present invention are preferred embodiments of the present invention, and the scope of the present invention is not limited by these embodiments, so: all equivalent changes made according to the structure, shape and principle of the invention are covered by the protection scope of the invention.