Method for producing low-carbon steel cage for bearing and low-carbon steel cage

Abstract

The invention provides a method for manufacturing a retainer for a bearing, the retainer is made of low-carbon steel, and the method comprises the following steps: 1, placing the retainer in nitrocarburizing treatment equipment for nitrocarburizing treatment so as to form a nitrocarburizing layer on the surface of the retainer; the low-carbon steel retainer comprises a nitrocarburizing layer formed through nitrocarburizing treatment, and the nitrocarburizing layer comprises a high-nitrogen white bright layer formed on the outer surface of the retainer through nitrocarburizing treatment; and the high-nitrogen diffusion layer is formed below the high-nitrogen white bright layer through nitrocarburizing treatment. Compared with the prior art, the low-carbon steel retainer has excellent corrosion resistance, wear resistance and protection on the corrosion-resistant layer, so that the low-carbon steel retainer can replace brass and stainless steel retainers to be used in a high-corrosion environment, and the cost of the whole bearing is greatly reduced. And in some applications, the cost is reduced by 50%-70%.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a low-carbon steel cage for a bearing and a low-carbon steel cage. Background Art

[0002] Bearings are common components used in various mechanical equipment and generally include an inner ring, an outer ring, rolling elements, and a cage for holding the rolling elements in place. Depending on the equipment to which the bearing is applied, the cage can be made of a variety of different materials.

[0003] For mechanical equipment operating in harsh working environments, especially in highly corrosive environments such as mining machinery, chemical equipment, and lithium battery manufacturing equipment, the cages of bearings are usually made of corrosion-resistant materials such as brass and stainless steel. However, cages made of brass, stainless steel, etc. are relatively costly. Other materials with lower costs are not used in such highly corrosive environments due to their poor corrosion resistance.

[0004] Therefore, there is a need in the art for a bearing cage that can effectively reduce costs and be used in highly corrosive environments. Summary of the Invention

[0005] In view of the problems and needs mentioned above, the present disclosure proposes a novel technical solution, which solves the above problems and brings other technical effects due to the following technical features.

[0006] The present invention provides a method for manufacturing a cage for a bearing, the cage being made of low-carbon steel, the method comprising step 1: placing the cage in a nitrocarburizing treatment device for nitrocarburizing treatment to form a nitrocarburized layer on the surface of the cage.

[0007] The present invention also provides a low-carbon steel cage, comprising: a nitrocarburized layer formed by nitrocarburizing treatment, the nitrocarburized layer comprising: a high-nitrogen white layer formed by nitrocarburizing treatment on the outer surface of the cage; a high-nitrogen diffusion layer formed under the high-nitrogen white layer by the nitrocarburizing treatment.

[0008] The low-carbon steel cage of the present invention has excellent corrosion resistance, while also taking into account wear resistance and protection of the corrosion-resistant layer, enabling the low-carbon steel cage to also replace brass and stainless steel cages in highly corrosive environments, greatly reducing the cost of the entire bearing. In some applications, the cost is reduced by up to 50%-70%. Brief Description of the Drawings

[0009] Figure 1 Schematic diagram of a method for manufacturing a low-carbon steel cage for a bearing according to a preferred embodiment of the present invention.

[0010] Figure 2 ForFigure 1 Schematic diagram of another preferred embodiment of the method shown.

[0011] The accompanying drawings are schematic illustrations not drawn to scale and should not be construed as limiting any specific technical parameters. Detailed implementation manners

[0012] In order to make the objectives, technical solutions and advantages of the technical solutions of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of specific embodiments of the present disclosure. The same reference numerals in the drawings represent the same components. It should be noted that the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts fall within the scope of protection of the present disclosure.

[0013] In view of the technical problems described above, the present invention proposes to use low-cost low-carbon steel to manufacture bearing cages. However, compared with brass and stainless steel, low-carbon steel has poor corrosion resistance and is not suitable for highly corrosive environments. Therefore, the present invention further proposes a method for manufacturing a low-carbon steel cage, such that low-carbon steel, which is considered in the art as not usable for highly corrosive environments, can also be used to manufacture cages. Furthermore, the present invention proposes a low-carbon steel cage, comprising: a nitrocarburized layer formed by nitrocarburizing treatment, the nitrocarburized layer comprising: a high-nitrogen bright layer formed by nitrocarburizing treatment on the outer surface of the cage; a high-nitrogen diffusion layer formed by the nitrocarburizing treatment below the high-nitrogen bright layer. Preferably, the low-carbon steel cage further comprises an oxide protective film formed on the outer layer of the nitrocarburized layer.

[0014] The following describes the present invention with reference to Figure 1 preferred embodiments of

[0015] The method for manufacturing a low-carbon steel cage according to the present invention comprises: Step 1: Placing the low-carbon steel cage in a nitrocarburizing treatment device for nitrocarburizing treatment to form a nitrocarburized layer on the surface of the cage.

[0016] By performing nitrocarburizing treatment on the low-carbon steel cage, a corrosion-resistant nitrocarburized layer can be formed on the surface of the cage, such that the low-carbon steel cage can also be used in highly corrosive environments. Preferably, the carbon content of the low-carbon steel used to manufacture the cage is <0.2%, and it can be selected from, for example, SPHD among GB / T 5213 DC01, DC03, DC04, DC05, ISO 3573 CR3, S275JR or JIAG3131.

[0017] Preferably, the thickness of the nitrocarburized layer is 100 - 700 μm, more preferably 200 - 600 μm. Further preferably, the nitrocarburized layer may include a high-nitrogen bright layer on the surface and a high-nitrogen diffusion layer below the high-nitrogen bright layer. The bright layer is a layer with special properties formed on the surface of the cage after nitrocarburizing treatment. Its presence is beneficial to improving the corrosion resistance of the cage, etc., while the high-nitrogen diffusion layer further provides wear resistance for the cage.

[0018] However, the high-nitrogen bright layer also has a certain brittleness. Therefore, in order to further reduce the brittleness of the bright layer, the present invention further proposes to perform the nitrocarburizing treatment in an atmosphere of ammonia and carbon dioxide. Specifically, at the treatment temperature according to the present invention (detailed later), during the nitrocarburizing treatment, the ammonia decomposes to provide active nitrogen atoms for penetration into the surface of the cage, which is the main gas during the nitrocarburizing treatment; while carbon dioxide can provide active carbon atoms, and some carbon atoms will also penetrate into the surface of the cage together with the nitrogen atoms. At the same time, the active carbon atoms can also promote the formation of the bright layer and reduce the brittleness of the bright layer. Therefore, the addition of carbon dioxide is not only used to form the nitrocarburized layer, accelerating the nitrocarburizing treatment speed and significantly improving the treatment efficiency, but also solves the problem of the brittleness of the bright layer. Therefore, after performing this treatment according to the present invention, a nitrocarburized layer will surely be formed on the surface of the cage. In other words, as long as this treatment according to the method of the present invention is carried out, a nitrocarburized layer with excellent performance can be obtained on the surface of the cage.

[0019] Preferably, the nitrocarburizing treatment can be carried out in a high-sealing nitrocarburizing atmosphere furnace or a vacuum nitrocarburizing furnace.

[0020] Preferably, the nitrocarburizing treatment can be carried out at a temperature of 480°C - 650°C, more preferably at a temperature of 550°C - 650°C.

[0021] Preferably, during the nitrocarburizing treatment, the ammonia flow rate is 5.5 - 20 m 3 / h (cubic meters per hour), more preferably 7 - 20 m 3 / h.

[0022] Preferably, during the nitrocarburizing treatment, the carbon dioxide flow rate is 0.5 - 1.2 m 3 / h, more preferably 0.7 - 1.1 m 3 / h.

[0023] Preferably, the nitrocarburizing treatment time is 2 - 6 hours, more preferably 3 - 5 hours.

[0024] Preferably, during the nitrocarburizing treatment, nitrogen is also used as a carrier gas to play a role in stabilizing the furnace atmosphere, and its flow rate is 4 - 15 m 3 / h, preferably 8 - 15 m 3 / h.

[0025] Preferably, the nitrocarburizing treatment is carried out in a nitrocarburizing atmosphere furnace with high tightness or a vacuum nitrocarburizing furnace.

[0026] Although according to the above method, a corrosion-resistant nitrocarburized layer can be formed on the surface of the cage, in order to further improve the performance of the cage, the present invention also proposes to perform an optimization treatment on the cage after the treatment.

[0027] Specifically, according to a preferred embodiment of the present invention, the method may further include step 2: performing a post-oxidation treatment on the nitrocarburized cage to form an oxide protective film (such as a magnetite film) on the outer layer of the nitrocarburized layer to better protect the underlying nitrocarburized layer. Preferably, the thickness of the oxide protective film is 0.5 - 15 μm, more preferably 6 μm or 15 μm.

[0028] Further preferably, the post-oxidation treatment can be carried out in an atmosphere of water vapor and nitrogen, where nitrogen still acts as a carrier gas while water vapor plays an oxidizing role. The post-oxidation treatment can be carried out in the same nitrocarburizing furnace used in the aforementioned nitrocarburizing treatment process, or can be carried out in another post-oxidation furnace after the cage is taken out.

[0029] Preferably, the post-oxidation treatment can be carried out in a temperature range of 460°C - 570°C, more preferably in a temperature range of 480°C - 550°C.

[0030] Preferably, in the post-oxidation treatment, the water vapor is 4 - 15 kg / h, more preferably 8 - 15 kg / h. Preferably, in the post-oxidation treatment, the nitrogen is 2 - 15 m 3 / h, more preferably 9 - 12 m 3 / h. Preferably, the post-oxidation treatment time is 1 - 4 hours, preferably 2 - 4 hours.

[0031] Further preferably, after the post-oxidation treatment, the cage can be naturally cooled in nitrogen, which can further stabilize the formed nitrocarburized layer, etc.

[0032] In addition, in order to be more conducive to the nitrocarburizing treatment in step 1, the present invention also proposes that a pre-oxidation treatment is further included before step 1 to form an oxide film on the surface of the cage, and this oxide film can accelerate the nitrocarburizing treatment speed in step 1.

[0033] Preferably, the pre-oxidation treatment is carried out in a temperature range of 380°C - 420°C (more preferably at 400°C) and lasts for 0.5 - 1.5 hours, more preferably lasts for 1 hour.

[0034] In Figure 1 the preferred embodiment shown, the preferred method according to the present invention includes all the preferred process steps of a pre-oxidation treatment (I), a nitrocarburizing treatment (II) in step 1 above, a post-oxidation treatment (III) in step 2 above, and natural cooling (IV) in nitrogen; in Figure 1 it, the ordinate is temperature and the abscissa is time.

[0035] As described above and as shown in the drawings, in Figure 1 the embodiment of, the nitrocarburizing treatment is carried out at the process-set temperature. More preferably, as Figure 2 shown, with other process parameters remaining unchanged, the nitrocarburizing treatment of the first stage (II-1) can be carried out at a first process-set temperature and subsequently the nitrocarburizing treatment of the second stage (II-2) can be carried out at a second process-set temperature. It should be understood that both the first process-set temperature and the second process-set temperature are within the preferred temperature range described above, and the specific temperature values and durations of the two stages can be determined according to actual needs.

[0036] Through this preferred embodiment, an oxide protective film, a high-nitrogen bright layer, and a high-nitrogen diffusion layer can be formed in sequence from the outside to the inside on the surface of the low-carbon steel cage. After testing, the cage manufactured by the method according to the present invention achieved no rusting in 360 hours in the neutral salt spray corrosion test and no rusting in 168 hours in the acidic salt spray corrosion test.

[0037] In summary, the method of the present invention provides excellent corrosion resistance for the cage, while taking into account wear resistance and the protection of the corrosion-resistant layer, enabling the low-carbon steel cage to also replace brass and stainless steel cages for use in highly corrosive environments, greatly reducing the cost of the entire bearing. In some applications, the cost is reduced by up to 50%-70%.

[0038] The exemplary embodiments of the present disclosure have been described in detail above with reference to the preferred embodiments. However, those skilled in the art can understand that, without departing from the concept of the present disclosure, various modifications and variations can be made to the above specific embodiments, and various combinations of the technical features and structures proposed by the present disclosure can be made without exceeding the protection scope of the present disclosure. The protection scope of the present disclosure is determined by the appended claims.

Claims

1. A method for manufacturing a cage for a bearing by nitrocarburizing and post-oxidation, the cage being made of low carbon steel, the method comprising: Step 1: Place the cage in a nitrocarburizing treatment device for nitrocarburizing treatment to form a nitrocarburizing layer on the surface of the cage.

2. The method of claim 1, wherein: The nitrocarburized layer comprises a high nitrogen white bright layer on the surface and a high nitrogen diffusion layer below the high nitrogen white bright layer. Preferably, the nitrocarburized layer has a thickness of 100-700 μm.

3. The method of claim 2, wherein: Step 1 includes: performing nitrocarburizing treatment in an atmosphere of ammonia and carbon dioxide, wherein during the nitrocarburizing treatment, ammonia decomposes to provide nitrogen atoms for penetrating into the surface of the retainer, and carbon dioxide provides active carbon atoms to promote the formation of a white bright layer and reduce the brittleness of the white bright layer.

4. The method of claim 3, wherein: The nitrocarburizing treatment is carried out in a highly sealed nitrocarburizing atmosphere furnace or a vacuum nitrocarburizing furnace; The nitrocarburizing treatment is carried out at a temperature of 480°C to 650°C, preferably, the nitrocarburizing treatment is carried out at a process setting temperature, or a first stage of nitrocarburizing treatment is carried out at a first process setting temperature and then a second stage of nitrocarburizing treatment is carried out at a second process setting temperature; Ammonia flow rate is 5.5-20m 3 / h; The carbon dioxide flow rate is 0.5-1.2m 3 / h; The nitrocarburizing treatment time is 2-6 hours; and / or During the nitrocarburizing process, nitrogen is also used as a carrier gas with a flow rate of 4-15m 3 / h.

5. The method of claim 1, further comprising: Step 2: Post-oxidation treatment is performed on the nitrocarburized retaining frame to form an oxide protective film on the outer layer of the nitrocarburized layer; preferably, the oxide protective film has a thickness of 0.5-15 μm.

6. The method of claim 5, wherein: The post-oxidation treatment is performed in an atmosphere of water vapor and nitrogen.

7. The method of claim 6, wherein: Performing the post-oxidation treatment at a temperature in the range of 460°C to 570°C; Water vapor is 4-15kg / h; Nitrogen: 2-15m 3 / h The post-oxidation treatment time is 1-4 hours.

8. The method of claim 5, wherein: After the post-oxidation treatment, the cage was cooled in nitrogen.

9. The method of claim 1, wherein: Before step 1, a pre-oxidation treatment is also included to form an oxide film on the surface of the retainer to accelerate the nitrocarburizing treatment speed in step 1; preferably, the pre-oxidation treatment is performed within a temperature range of 380°C-420°C and lasts for 0.5-1.5 hours.

10. A low carbon steel cage, comprising: A nitrocarburizing layer formed by nitrocarburizing treatment, wherein the nitrocarburizing layer comprises: A high nitrogen white bright layer formed by nitrocarburizing treatment on the outer surface of the cage; A high nitrogen diffusion layer is formed below the high nitrogen white bright layer through the nitrocarburizing treatment; Preferably, the low carbon steel cage further comprises an oxide protective film formed on the outer layer of the nitrocarburized layer.

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