Method and device for controlling residual austenite of bearing parts and integrating with hydrocarbon cleaning

Abstract

This invention discloses an integrated method and apparatus for controlling residual austenite and hydrocarbon cleaning in bearing parts, belonging to the field of bearing heat treatment post-processing technology. The method involves alternately injecting a cold hydrocarbon cleaning solution at 5-12°C and a hot hydrocarbon cleaning solution at 90-110°C into a vacuum-sealed chamber at 80-150 Pa, immersing each section for 25-35 minutes, and performing 2-4 alternating cold and hot cycles. The cold liquid stage simultaneously achieves residual austenite control and preliminary cleaning, while the hot liquid stage completes deep cleaning. After the cycle, the parts are vacuum-dried and discharged. The apparatus includes a sealed cleaning chamber, a vacuum system, a cold liquid circulation system, a hot liquid circulation system, and an automatic control system, capable of automatically completing the entire process. This invention integrates residual austenite control and cleaning processes, improving production efficiency, ensuring residual austenite control accuracy, preventing part oxidation through full vacuum, achieving high cleanliness, and eliminating carbon black and oil stains on the surface, reducing environmental pollution caused by shot blasting, etc. The sealed hydrocarbon liquid circulation significantly reduces wastewater discharge, saving energy and protecting the environment. It is suitable for post-processing of various bearing parts after quenching.

Description

Technical Field

[0001] This invention relates to the field of post-heat treatment technology for bearing parts, and particularly to the process and equipment for controlling residual austenite and cleaning the surface of bearing parts after quenching. Background Technology

[0002] After quenching and heat treatment, core components such as bearing rings and rolling elements inevitably retain a certain amount of residual austenite in their metallographic structure. Excessive residual austenite content directly leads to problems such as unstable dimensional accuracy, decreased surface hardness, and shortened contact fatigue life during long-term bearing service, severely affecting bearing performance and operational reliability. Therefore, controlling the residual austenite content is a key quality control indicator in the bearing heat treatment process.

[0003] The current standard post-treatment process for bearing parts after quenching in the industry is as follows: first, the parts are cleaned with hot alkaline water at around 60°C to remove surface quenching oil and other contaminants; then, they are immersed in cold alkaline water at 5-12°C for cold treatment to promote the transformation of residual austenite into a stable phase; finally, they undergo tempering. In this model, the cleaning process and the residual austenite control process are independent of each other and are completed in different equipment and at different workstations.

[0004] The aforementioned traditional process has inherent technical defects: when parts are first cleaned with high-temperature alkaline water, the high temperature has an aging and stabilizing effect on the residual austenite inside the parts. This leads to a significant decrease in the transformation driving force of the residual austenite during the subsequent low-temperature alkaline water immersion process, and the effect of cold treatment in reducing residual austenite is significantly weakened, making it difficult to consistently control the residual austenite content to the ideal level. Furthermore, the existing process uses alkaline aqueous solutions as the cleaning and cold treatment medium. During the quenching process, a large amount of quenching oil adhering to the solution mixes into the alkaline water system, not only continuously reducing the cleaning effect but also generating a large amount of oily and alkaline wastewater. This results in high wastewater treatment costs and significant environmental pressure, which is inconsistent with the green manufacturing development direction of the bearing industry.

[0005] Furthermore, since the cleaning and cold treatment processes are handled by two separate sets of equipment, parts need to be transferred between different workstations, resulting in long production cycles, low overall production efficiency, large equipment footprint, and high initial investment and maintenance costs. Moreover, the open cold treatment environment easily leads to frost formation and oxidation discoloration on the parts' surfaces, directly affecting the surface quality and dimensional accuracy of subsequent grinding processes. Currently, there is no integrated process or dedicated equipment in the industry capable of simultaneously completing the control of residual austenite and precision hydrocarbon cleaning of bearing parts within the same single unit and in the same process flow. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an integrated method and apparatus for controlling residual austenite and cleaning hydrocarbons in bearing parts.

[0007] To achieve the above objectives, the present invention provides the following technical solution: an integrated treatment method for controlling residual austenite in bearing parts and cleaning hydrocarbons, comprising the following steps: (1) placing the bearing parts after quenching heat treatment in a sealed cavity, sealing the cavity and then pumping the air pressure in the cavity to 80-150 Pa and maintaining it during subsequent treatment; (2) Inject cold hydrocarbon cleaning fluid at a temperature of 5-12°C into the sealed cavity until the bearing parts are completely submerged in the liquid, and soak for 25-35 minutes. (3) Drain all the cold hydrocarbon cleaning fluid from the sealed cavity; (4) Inject hot hydrocarbon cleaning fluid at a temperature of 90-110°C into the sealed cavity until the bearing parts are completely submerged in the liquid, and clean for 25-35 minutes. (5) Drain all the hot hydrocarbon cleaning fluid from the sealed cavity; (6) Repeat steps (2) to (5) for 2 to 4 cycles of alternating hot and cold.

[0008] The present invention is further configured such that the temperature of the cold hydrocarbon cleaning solution in step (2) is 6 to 10°C.

[0009] The present invention is further configured such that in steps (3) and (5), the single-step discharge time of the hydrocarbon cleaning solution does not exceed 2 minutes.

[0010] The present invention is further configured such that after step (6) is completed, a vacuum drying step is also included: maintaining the gas pressure in the cavity at 80-150 Pa, raising the cavity temperature to 110-120°C, and keeping it at that temperature for 10-20 minutes to allow the residual hydrocarbon cleaning liquid on the surface of the bearing parts to completely evaporate; after drying, inert gas is introduced into the cavity to restore normal pressure, and the bearing parts are removed.

[0011] The present invention is further configured such that: both the cold hydrocarbon cleaning solution and the hot hydrocarbon cleaning solution are low-freezing-point isoalkane-type hydrocarbon solvents, with a freezing point ≤0℃ and a flash point ≥55℃.

[0012] The present invention is further configured such that: the cold hydrocarbon cleaning fluid discharged in step (3) is returned to an independent cold liquid storage tank for recycling, and the hot hydrocarbon cleaning fluid discharged in step (5) is returned to an independent hot liquid storage tank for recycling; the quenching oil dissolved in the hydrocarbon cleaning fluid during the cleaning process is separated and recycled.

[0013] On the other hand, the present invention provides an integrated device for controlling residual austenite in bearing parts and cleaning hydrocarbons to implement the above-mentioned method. The specific technical solution is as follows: it includes a sealed cleaning chamber, a vacuum system, a cold liquid storage and circulation system, a hot liquid storage and circulation system, and a control system. The sealed cleaning chamber is used to accommodate bearing parts and can withstand a vacuum environment of 80–150 Pa and temperature fluctuations of 0°C–120°C. The vacuum system is connected to the sealed cleaning chamber and is used to pump the gas pressure inside the chamber to and maintain it at 80–150 Pa. The cold liquid storage and circulation system includes a cold liquid storage tank, a refrigeration device, and a pumping pipeline, used to cool the hydrocarbon cleaning fluid and maintain it stably at 5–12°C, and to inject and return the fluid to the sealed cleaning chamber. The hot liquid storage and circulation system includes a hot liquid storage tank, a heating device, and a pumping pipeline, used to heat the hydrocarbon cleaning fluid and maintain it stably at 90–110°C, and to inject and return the fluid to the sealed cleaning chamber. The control system is electrically connected to the vacuum system, the cold liquid storage and circulation system, and the hot liquid storage and circulation system, respectively, and is used to automatically control the timing, temperature, vacuum degree and number of cycles of alternating cold and hot liquid circulation.

[0014] The invention is further configured such that: the sealed cleaning chamber is made of low-sulfur, low-aromatic compatibility stainless steel; the welds on the inner surface of the chamber are fully penetrated and polished; all welds are inspected and accepted by 100% radiographic testing and have no linear defects; the wall thickness of the chamber is designed and verified according to the external pressure vessel specifications.

[0015] The present invention is further configured such that: the cold liquid storage and circulation system and the hot liquid storage and circulation system are respectively provided with independent storage tanks and independent pumping pipelines, and the cold and hot hydrocarbon cleaning liquids do not mix with each other during the operation of the device and circulate independently.

[0016] The present invention is further configured to include a hydrocarbon vapor concentration detection and alarm unit, which is located in the external environment of the sealed cleaning chamber; when the hydrocarbon vapor concentration in the environment reaches 25% of the lower explosive limit, the hydrocarbon vapor concentration detection and alarm unit triggers an alarm signal, and the control system control device stops.

[0017] By adopting the above technical solution, the following technical effects are achieved: 1. Process integration significantly improves production efficiency: The traditionally independent cold treatment (Paralympic control) process and cleaning process are combined into one process and completed continuously in the same device, eliminating the transfer time between processes, shortening the production cycle, and improving overall production efficiency; at the same time, one device replaces two traditional devices, namely the cold treatment tank and the cleaning machine, reducing the workshop floor space and lowering the initial investment and maintenance costs of the equipment.

[0018] 2. Precise and stable control of retained austenite: The alternating hot and cold process of first immersing at low temperature and then cleaning at high temperature avoids the problem of residual austenite aging caused by the hot cleaning process in traditional processes; the temperature of each part is uniform and the cooling consistency is good when immersed in low-temperature hydrocarbon liquid, the transformation process of retained austenite is stable and controllable, and the content of retained austenite can be stably controlled to a low level, with control precision better than traditional cold treatment methods.

[0019] 3. Significantly improved cleaning effect: Alternating immersion in hot and cold hydrocarbon solutions causes the parts to experience a temperature contraction-expansion effect, which helps to remove residues from complex structures such as blind holes and grooves. The deep cleaning effect is superior to that of cleaning processes using a single temperature.

[0020] 4. Vacuum protection ensures surface quality: The entire process is carried out in a vacuum environment of 80-150 Pa, so there is no moisture condensation on the surface of the parts, and there will be no problems such as frost, oxidation and discoloration, which ensures the surface quality and dimensional accuracy of the finished product in subsequent grinding.

[0021] 5. Green and environmentally friendly, energy-saving and emission-reducing: The hydrocarbon cleaning fluid is circulated in a sealed system with extremely low volatilization loss. After replacing the traditional alkaline water cleaning system, it can significantly reduce wastewater discharge and reduce environmental pressure. The quenching oil dissolved during the cleaning process can be separated, recycled and reused. At the same time, the parts are still warm after being cleaned with hot hydrocarbons and can directly enter the tempering process, reducing the temperature difference of tempering heating and reducing energy consumption. Attached Figure Description

[0022] Figure 1 is a schematic diagram of the overall structure of the integrated device of the present invention; In the diagram: 1. Sealed cleaning chamber; 2. Vacuum pump assembly; 3. Cold liquid storage tank; 4. Refrigeration unit; 5. Cold liquid pump; 6. Hot liquid storage tank; 7. Heating device; 8. Hot liquid pump; 9. Cold and hot switching valve assembly; 10. Liquid level sensor; 11. Temperature sensor; 12. Vacuum pressure sensor; 13. Control cabinet (PLC); 14. Hydrogen vapor concentration detector. Detailed Implementation

[0023] Reference Figure 1 The embodiments of the present invention will be further described below.

[0024] Example 1: Integrated treatment of GCr15 bearing rings after quenching Workpiece parameters: GCr15 bearing ring, outer diameter 85mm, inner diameter 80mm, width 10mm, after standard quenching heat treatment. The process parameters are as follows: heating temperature 850°C, heating time 1 hour, tempering temperature 160°C, and initial residual austenite content of approximately 10-20%.

[0025] Processing equipment: The integrated device for controlling residual austenite in bearing parts and cleaning hydrocarbons as described in this invention is adopted.

[0026] Processing procedure: Step 1: Loading and vacuuming: Arrange the quenched bearing rings neatly into the material basket, place them in the sealed cleaning chamber 1, close the chamber door and lock the seal; start the vacuum pump group 2, pump the chamber air pressure to 100 Pa within 5 minutes, and maintain this vacuum level throughout the process.

[0027] Step 2: Cold liquid immersion control: Turn on the cold liquid pump 5 and the corresponding valve group, and inject cold hydrocarbon cleaning solution (isoparaffin type, flash point 62℃, freezing point -15℃) at a temperature of 8℃ into the cavity until the liquid surface completely submerges the workpiece. Stop the injection and keep immersing for 30 minutes.

[0028] Step 3: Cold liquid return: Open the cold liquid return pipeline and pump all the cold hydrocarbon liquid in the chamber back to the cold liquid storage tank 3 within 1.5 minutes for subsequent recycling.

[0029] Step 4: Deep hydrothermal cleaning: Turn on the hydrothermal pump 8 and the corresponding valve group, and inject hot hydrocarbon cleaning fluid at a temperature of 100℃ into the cavity until the workpiece is completely submerged. Stop injecting the fluid and keep cleaning for 30 minutes to fully dissolve and remove the quenching oil and dirt from the surface of the parts.

[0030] Step 5: Hydrothermal return: Open the hydrothermal return pipeline and pump all the hot hydrocarbon liquid in the cavity back to the hydrothermal storage tank 6 within 1.5 minutes for subsequent recycling.

[0031] Step 6: Cyclic Processing: Repeat the above process of cold liquid immersion - draining cold liquid - hot liquid cleaning - draining hot liquid, for a total of 3 alternating cold and hot cycles.

[0032] Step 7: Vacuum drying: After the cycle is completed, maintain the vacuum degree of the chamber at 100 Pa, start the chamber jacket heating system, raise the chamber temperature to 115℃, and keep it at this temperature for 15 minutes to allow the residual hydrocarbon solvents on the surface of the parts to completely evaporate.

[0033] Step 8: Discharge: Fill the chamber with high-purity nitrogen to restore atmospheric pressure, open the chamber door, and remove the bearing ring.

[0034] Processing result: Surface quality: The surface of the parts is clean and bright, without frost marks or oxidation discoloration, meeting the surface requirements for subsequent grinding. Residual austenite content: X-ray diffraction test showed that the residual austenite content of the parts was ≤8%, which meets the bearing product quality standards; Hardness uniformity: The surface hardness of the parts is uniform, with no obvious hardness difference.

[0035] The above description is merely a preferred embodiment of the present invention. The scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, any improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A method for integrated control of residual austenite and hydrocarbon cleaning in bearing parts, characterized in that: Includes the following steps: (1) Place the bearing parts that have undergone quenching heat treatment into a sealed cavity, seal the cavity, and then pump the air pressure in the cavity to 80-150 Pa and maintain it during subsequent processing; (2) Inject cold hydrocarbon cleaning fluid at a temperature of 5-12°C into the sealed cavity until the bearing parts are completely submerged in the liquid, and soak for 25-35 minutes. (3) Drain all the cold hydrocarbon cleaning fluid from the sealed cavity; (4) Inject hot hydrocarbon cleaning fluid at a temperature of 90-110°C into the sealed cavity until the bearing parts are completely submerged in the liquid, and clean for 25-35 minutes. (5) Drain all the hot hydrocarbon cleaning fluid from the sealed cavity; (6) Repeat steps (2) to (5) for 2 to 4 cycles of alternating hot and cold.

2. The integrated treatment method for controlling residual austenite and hydrocarbon cleaning of bearing parts according to claim 1, characterized in that: The temperature of the cold hydrocarbon cleaning solution in step (2) is 6 to 10°C.

3. The integrated treatment method for controlling residual austenite and hydrocarbon cleaning of bearing parts according to claim 1, characterized in that: In steps (3) and (5), the single-step discharge time of the hydrocarbon cleaning solution does not exceed 2 minutes.

4. The integrated treatment method for controlling residual austenite and hydrocarbon cleaning of bearing parts according to claim 1, characterized in that: After step (6) is completed, a vacuum drying step is also included: maintain the gas pressure in the cavity at 80-150 Pa, raise the cavity temperature to 110-120℃, keep it at that temperature for 10-20 minutes, so that the residual hydrocarbon cleaning liquid on the surface of the bearing parts can be completely evaporated; after drying, fill the cavity with inert gas to restore normal pressure, and take out the bearing parts.

5. The integrated treatment method for controlling residual austenite and hydrocarbon cleaning of bearing parts according to claim 1, characterized in that: Both the cold hydrocarbon cleaning solution and the hot hydrocarbon cleaning solution are low-freezing-point isoalkane-type hydrocarbon solvents, with a freezing point ≤0℃ and a flash point ≥55℃.

6. The integrated treatment method for controlling residual austenite and hydrocarbon cleaning of bearing parts according to claim 1, characterized in that: The cold hydrocarbon cleaning fluid discharged in step (3) is returned to a separate cold liquid storage tank for recycling, and the hot hydrocarbon cleaning fluid discharged in step (5) is returned to a separate hot liquid storage tank for recycling; the quenching oil dissolved in the hydrocarbon cleaning fluid during the cleaning process is separated and recycled.

7. An integrated device for controlling residual austenite and cleaning hydrocarbons in bearing parts, used to implement the processing method described in claim 1, characterized in that: The system includes a sealed cleaning chamber, a vacuum system, a cold liquid storage and circulation system, a hot liquid storage and circulation system, and a control system. The sealed cleaning chamber houses bearing components and can withstand a vacuum environment of 80–150 Pa and temperature fluctuations of 0–120 °C. The vacuum system is connected to the sealed cleaning chamber and is used to pump and maintain the pressure within the chamber at 80–150 Pa. The cold liquid storage and circulation system includes a cold liquid storage tank, a refrigeration device, and pumping pipelines, used to cool and stably maintain the hydrocarbon cleaning fluid at 5–12 °C, and to inject and return the fluid to the sealed cleaning chamber. The hot liquid storage and circulation system includes a hot liquid storage tank, a heating device, and pumping pipelines, used to heat and stably maintain the hydrocarbon cleaning fluid at 90–110 °C, and to inject and return the fluid to the sealed cleaning chamber. The control system is electrically connected to the vacuum system, the cold liquid storage and circulation system, and the hot liquid storage and circulation system, and is used to automatically control the timing, temperature, vacuum level, and number of cycles of the alternating circulation of cold and hot liquids.

8. The integrated device for controlling residual austenite in bearing parts and cleaning hydrocarbons according to claim 7, characterized in that: The sealed cleaning chamber is made of low-sulfur, low-aromatic compatibility stainless steel. The welds on the inner surface of the chamber are fully penetrated and polished. All welds are inspected and accepted by radiographic testing and have no linear defects. The wall thickness of the chamber is designed and verified according to the external pressure vessel specifications.

9. The integrated device for controlling residual austenite in bearing parts and cleaning hydrocarbons according to claim 7, characterized in that: The cold liquid storage and circulation system and the hot liquid storage and circulation system are each equipped with independent storage tanks and independent pumping pipelines. The cold and hot hydrocarbon cleaning liquids do not mix during the operation of the device and circulate independently.

10. The integrated device for controlling residual austenite and cleaning hydrocarbons in bearing parts according to claim 7, characterized in that: It also includes a hydrocarbon vapor concentration detection and alarm unit, which is installed in the external environment of the sealed cleaning chamber; when the hydrocarbon vapor concentration in the environment reaches 25% of the lower explosive limit, the hydrocarbon vapor concentration detection and alarm unit triggers an alarm signal, and the control system control device stops.

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