Method for improving fatigue resistance of alloy gear through beeswax protection

Abstract

The invention discloses a method for protecting and improving the fatigue resistance of an alloy gear by beewax. The method comprises the following steps: S1, coating beewax; s2, copper plating; s3, nitriding is conducted, specifically, the tooth part is subjected to nitriding treatment, after nitriding is completed, the tooth part is coated with beewax again, 3-5 layers of beewax are evenly smeared, and the whole tooth part is completely covered with the beewax; and S4, copper removal is conducted, specifically, the gear body is subjected to copper removal treatment. The beeswax is used for protecting the tooth portion of the part, the nitriding layer obtained after nitriding is reserved, the anti-fatigue life of the gear can be remarkably prolonged through protection of the beeswax on the fading layer, and the alloy gear is low in cost, convenient to operate, free of pollution and residues and free of damage.

Description

Technical Field

[0001] This invention relates to the field of alloy material processing technology, specifically to a method for improving the fatigue resistance of alloy gears by protecting them with beeswax. Background Technology

[0002] 38CrMoAlA is an important alloy structural steel, its most prominent characteristic being its excellent nitriding performance. Currently, driving and driven bevel gears made from 38CrMoAlA undergo nitriding treatment on the teeth, while the remaining surfaces are copper-plated before nitriding. During this process, the teeth are protected, and nitriding is performed only after copper plating. This process results in the formation of a large amount of aluminum nitride (AlN), γ-phase (Fe4N), and chromium nitride (CrN) on the teeth, giving them a silvery-white color. However, the copper-plated surface requires subsequent copper removal. During this process, the teeth are not protected; instead, Cr2O3 grinding and sulfuric acid cleaning are used. This process severely damages the precise structure formed by nitriding. The hardness of chromium trioxide (HV 2600-3000) is much higher than that of the nitrided layer (HV 1100-1200), and during gear meshing, the hardest compound layer on the surface is scraped away, resulting in a 20-50% reduction in the effective nitriding depth. Microscopic scratches are left on the surface, becoming the initiation point of fatigue cracks.

[0003] In addition, Cr2O3 particles embedded in scratches or tooth roots continuously induce abrasive wear during gear meshing, accelerating tooth surface failure. The specific reaction formula and principle are as follows:

[0004] AlN hydrolysis: AlN + 3H2O → Al(OH)3 + NH3, which will weaken the high-hardness AlN phase;

[0005] Dissolution of γ′ phase (Fe4N): The acidic environment corrodes the dense Fe4N layer, destroying the wear-resistant barrier;

[0006] Grain boundary corrosion: Sulfuric acid erodes along the vein-like nitride network of the nitride diffusion layer, inducing microcracks;

[0007] If the cleaning time is too long or the concentration is too high, the acid may penetrate the nitride layer and corrode the tempered substrate, resulting in a decrease in core strength.

[0008] Therefore, strengthening the protection of driving and driven bevel gears made of 38CrMOAlA material is particularly important. Beeswax is a potential gear protectant; however, the surface of 38CrMOAlA material is smooth, and beeswax, a natural wax whose main components are esters, fatty acids, and hydrocarbons, has very limited adhesion to highly smooth metal surfaces. Under the mechanical forces and friction of gear meshing, the beeswax coating will quickly be scraped off, worn away, or peeled off, failing to provide long-term stable protection. Therefore, exploring the appropriate timing and process for applying beeswax is currently unexplored. Summary of the Invention

[0009] To address the aforementioned problems, this invention provides...

[0010] The technical solution of this invention is:

[0011] A method for improving the fatigue resistance of alloy gears by beeswax protection includes the following steps:

[0012] S1. Coating with beeswax: Take the alloy gear to be copper-plated and nitrided, the alloy gear includes teeth located at the edge and gear body, coat the teeth with beeswax, apply 3 to 5 layers evenly to fully cover the entire teeth;

[0013] S2, Copper plating: The gear body is copper plated, and after the copper plating is completed, the beeswax coating on the teeth is cleaned off.

[0014] S3, Nitriding: Nitriding is performed on the teeth. After nitriding, beeswax is applied to the teeth again, with 3 to 5 layers applied evenly to fully cover the entire teeth.

[0015] S4. Copper Removal: The gear body is subjected to copper removal treatment.

[0016] Furthermore, in S1 and S3, depending on the specific part of the tooth, the coating thickness of each layer of beeswax is: 10-20 μm on the tooth surface, 5-15 μm on the tooth root, and 5-10 μm on the tooth tip.

[0017] Note: Different beeswax coating thicknesses are specified for the three areas of tooth surface, tooth root, and tooth tip, which have different stress concentrations and wear conditions. Among them, the tooth surface is the main contact and transmission surface, bearing the greatest load, and requires the thickest protective layer. The tooth root is the place with the greatest bending stress, which is prone to fatigue cracks and also requires thick protection. The tooth tip has relatively less stress, so a thin layer is sufficient for protection. This differentiation avoids beeswax waste and ensures coating efficiency.

[0018] Furthermore, before performing S1, the alloy gear is pretreated: first, the alloy gear is immersed in an alkaline degreasing bath for 5-10 minutes, then immersed in an acid pickling bath for 5-10 minutes, and after being removed, it is rinsed with deionized water 1-2 times and dried.

[0019] Explanation: Pretreatment thoroughly removes grease, scale, and dirt from the gear surface, providing a clean and active substrate surface for beeswax. This allows the beeswax to adhere tightly, forming a seamless and complete protective film, fundamentally preventing the penetration of electroplating solutions or nitriding media.

[0020] Furthermore, the alkaline degreasing bath solution comprises, by weight, 20-40 parts sodium hydroxide, 20-30 parts sodium carbonate, 10-20 parts trisodium phosphate, 5-10 parts sodium silicate, and 1-5 parts surfactant.

[0021] Note: Through the synergistic effect of the components in the compound formula, various types of oil stains can be removed quickly and thoroughly, laying a solid foundation for subsequent processes.

[0022] Furthermore, the pickling solution is hydrochloric acid with a mass concentration of 15-20%.

[0023] Note: Pickling pretreatment can prevent blistering and peeling of the coating, and ensure that the nitriding process is carried out uniformly, resulting in a nitrided layer with excellent performance.

[0024] Further, in step S2, the copper plating process involves placing the alloy gear in an electroplating tank, adding an electroplating solution comprising 80–120 g / L hydroxyethylidene diphosphonic acid and 40–60 g / L copper sulfate, controlling the temperature at 40–55°C, and setting the cathode current density to 1–2.5 A / dm³. 2 The copper plating thickness is 40-80μm.

[0025] Note: HEDP copper plating is a cyanide-free copper plating process that avoids the use of highly toxic cyanide, making it environmentally friendly and in line with modern clean production requirements.

[0026] Furthermore, in S2, after copper plating is completed, the teeth of the alloy gear and the copper-plated gear body are cleaned with hot water at 60-80°C until the beeswax coating on the teeth is completely removed.

[0027] Note: Beeswax has a melting point of around 60-70℃, so it can be melted by hot water and washed away by running water. This cleaning method is thorough and will not cause any mechanical damage or chemical corrosion to the already plated copper layer or gear substrate. It does not require the use of organic solvents or other chemical stripping agents, is low in cost, and emits no harmful substances, making it safe and environmentally friendly.

[0028] Further, in S3, the nitriding process involves: loading the alloy gear into a nitriding furnace, injecting nitrogen gas to purge the air from the furnace, then heating the furnace to 500–530°C, and injecting ammonia gas at a rate of 5–8 m / s. 3 The injection rate is maintained at 5-10 h for 5-10 h, then increased to 540-560℃. The ammonia injection rate is reduced to 60-80% of the initial injection rate, and maintained at this temperature for 3-6 h. The temperature is then increased to 540-560℃, ammonia injection is stopped, and nitrogen is injected at a rate of 1-3 m / s. 3 The furnace is heated to a constant temperature for 2-4 hours, then cooled down with the furnace while nitrogen is continuously introduced until the temperature drops below 100°C. The nitrided layer thickness is 0.2-0.3 μm.

[0029] Note: By using a multi-stage composite nitriding process, the microstructure, thickness, and properties of the nitrided layer can be more precisely controlled than traditional single-stage nitriding. This results in a high-quality nitrided layer with high hardness, good toughness, and moderate thickness, which greatly improves the fatigue resistance and wear resistance of the teeth.

[0030] Further, in S4, the copper removal process is as follows: the alloy gear is placed in a nitric acid solution with a mass concentration of 10-15% and immersed at room temperature for 10-60 seconds. After removal, it is rinsed with deionized water and then immersed in a sodium carbonate solution with a mass concentration of 3-5% for 2-5 minutes. After removal, it is rinsed with deionized water and dried.

[0031] Note: Using nitric acid to remove copper can quickly and thoroughly dissolve the copper plating on the gear body, while having minimal impact on the already nitrided teeth (protected by beeswax) and the gear base. It also prevents secondary corrosion. After copper removal, acidic media may remain on the surface. Neutralizing with a weakly alkaline sodium carbonate solution can completely remove the residual acid, preventing corrosion of the gear during storage or use and ensuring the long-term stability of the product.

[0032] The beneficial effects of this invention are:

[0033] This invention discloses a method for improving the fatigue resistance of alloy gears using beeswax protection. Beeswax is used to protect the tooth area of ​​the part, while the nitrided layer is retained. The outermost bright white layer after nitriding is approximately 0.01–0.02 mm thick and consists of γ′ phase (Fe₄N) and a small amount of ε phase (Fe₂). 2-3 The compound layer consists of a dense and corrosion-resistant layer composed of nitrogen (N), followed by a diffusion layer located below the compound layer, with a total depth of 0.3–0.6 mm. Vein-like nitrides, such as AlN and CrN, diffuse along grain boundaries to form a network structure, reaching depths of over 0.3 mm. The high hardness of AlN directly imparts "armor-like" wear resistance to the surface, while the vein-like nitrides in the diffusion layer effectively inhibit crack propagation, significantly improving fatigue life. The γ′ phase and CrN together form a chemical barrier, especially superior to ordinary steel in chlorine-containing environments. In summary, protecting the desalination layer with beeswax can significantly improve the fatigue life of gears, and it is low-cost, easy to operate, pollution-free, residue-free, and does not damage alloy gears. Attached Figure Description

[0034] Figure 1 This is a cross-sectional view of the alloy gear to be processed in the method of the present invention.

[0035] Wherein, 1-tooth surface, 2-tooth root, 3-tooth tip. Detailed Implementation

[0036] Example 1

[0037] A method for improving the fatigue resistance of alloy gears by beeswax protection includes the following steps:

[0038] The alloy gears are pretreated as follows: First, the alloy gears are immersed in an alkaline degreasing bath for 8 minutes, then immersed in an acid pickling bath for 8 minutes. After removal, they are rinsed twice with deionized water and dried. The alkaline degreasing bath, by weight, includes 30 parts sodium hydroxide, 25 parts sodium carbonate, 15 parts trisodium phosphate, 8 parts sodium silicate, and 4 parts surfactant. The acid pickling bath is 16% hydrochloric acid by weight.

[0039] S1. Coating with beeswax: Take the alloy gear to be copper-plated and nitrided. The alloy gear includes the teeth at the edge and the gear body. Coat the teeth with beeswax, applying four even layers to fully cover the entire tooth. The thickness of each beeswax layer varies depending on the specific part of the tooth. Figure 1 As shown, tooth surface 1 is 15μm, tooth root 2 is 10μm, and tooth tip 3 is 8μm;

[0040] S2. Copper Plating: The gear body is copper plated. After copper plating, the beeswax coating on the teeth is cleaned off. The copper plating process involves placing the alloy gear in an electroplating tank, adding an electroplating solution containing 100g / L hydroxyethylidene diphosphonic acid and 50g / L copper sulfate, controlling the temperature at 50℃, and setting the cathode current density to 2A / dm³. 2 The copper plating thickness is 60μm. After the copper plating is completed, the teeth of the alloy gear and the copper-plated gear body are cleaned with 70℃ hot water until the beeswax coated on the teeth is completely removed.

[0041] S3. Nitriding: The gear teeth are nitrided. After nitriding, beeswax is applied to the teeth again, evenly in four layers, covering the entire tooth. The thickness of each beeswax layer varies depending on the specific part of the tooth: 14μm for tooth surface 1, 6μm for tooth root 2, and 6μm for tooth tip 3. The nitriding process involves: placing the alloy gear into a nitriding furnace, injecting nitrogen gas to purge the air from the furnace, then heating to 520℃ and injecting ammonia gas at a rate of 6m / s². 3 The injection rate is maintained at 8 h for 8 hours, then increased to 550℃. The ammonia injection rate is reduced to 70% of the initial injection rate and maintained for 4 hours. The temperature is then increased to 550℃, ammonia injection is stopped, and nitrogen is injected at a rate of 2 m / s². 3 / h, hold at temperature for 3h, then cool down with the furnace and continue to purge with nitrogen until the temperature drops below 100℃ and then remove from the furnace. The thickness of the nitrided layer is 0.25μm.

[0042] S4. Copper Removal: The gear body is subjected to copper removal treatment. The steps for copper removal treatment are as follows: place the alloy gear in a 12% nitric acid solution and soak it at room temperature for 30 seconds. After taking it out, rinse it with deionized water. Then soak it in a 4% sodium carbonate solution for 3 minutes. After taking it out, rinse it with deionized water and dry it.

[0043] Example 2

[0044] The difference between this embodiment and Embodiment 1 is that:

[0045] The alloy gears are pretreated as follows: First, the alloy gears are immersed in an alkaline degreasing tank for 5 minutes, then immersed in an acid pickling tank for 5 minutes. After removal, they are rinsed once with deionized water and dried.

[0046] Example 3

[0047] The difference between this embodiment and Embodiment 1 is that:

[0048] The alloy gears are pretreated as follows: First, the alloy gears are immersed in an alkaline degreasing bath for 10 minutes, then immersed in an acid pickling bath for 10 minutes. After removal, they are rinsed twice with deionized water and dried.

[0049] Example 4

[0050] The difference between this embodiment and Embodiment 1 is that:

[0051] The alkaline degreasing bath solution, by weight, includes 20 parts sodium hydroxide, 20 parts sodium carbonate, 10 parts trisodium phosphate, 5 parts sodium silicate, and 1 part surfactant.

[0052] Example 5

[0053] The difference between this embodiment and Embodiment 1 is that:

[0054] The alkaline degreasing bath solution, by weight, includes 40 parts sodium hydroxide, 30 parts sodium carbonate, 20 parts trisodium phosphate, 10 parts sodium silicate, and 5 parts surfactant.

[0055] Example 6

[0056] The difference between this embodiment and Embodiment 1 is that:

[0057] The pickling solution is 15% hydrochloric acid by mass.

[0058] Example 7

[0059] The difference between this embodiment and Embodiment 1 is that:

[0060] The pickling solution is 20% hydrochloric acid by mass.

[0061] Example 8

[0062] The difference between this embodiment and Embodiment 1 is that:

[0063] S1. Coating with beeswax: Take the alloy gear to be copper-plated and nitrided. The alloy gear includes the teeth at the edge and the gear body. Coat the teeth with beeswax, applying 3 layers evenly to fully cover the entire tooth. Depending on the specific part of the tooth, the coating thickness of each layer of beeswax is: 10μm for tooth surface 1, 5μm for tooth root 2, and 5μm for tooth tip 3.

[0064] Example 9

[0065] The difference between this embodiment and Embodiment 1 is that:

[0066] S1. Coating with beeswax: Take the alloy gear to be copper-plated and nitrided. The alloy gear includes the teeth at the edge and the gear body. Coat the teeth with beeswax, applying 5 layers evenly to fully cover the entire tooth. Depending on the specific part of the tooth, the coating thickness of each layer of beeswax is: 20μm for tooth surface 1, 15μm for tooth root 2, and 10μm for tooth tip 3.

[0067] Example 10

[0068] The difference between this embodiment and Embodiment 1 is that:

[0069] S2. Copper Plating: The gear body is copper plated. After copper plating, the beeswax coating on the teeth is cleaned off. The copper plating process involves placing the alloy gear in an electroplating tank, adding an electroplating solution containing 80 g / L hydroxyethylidene diphosphonic acid and 40 g / L copper sulfate, controlling the temperature at 55℃, and setting the cathode current density to 1 A / dm³. 2 The copper plating thickness is 40μm. After the copper plating is completed, the teeth of the alloy gear and the copper-plated gear body are cleaned with 60℃ hot water until the beeswax coating on the teeth is completely removed.

[0070] Example 11

[0071] The difference between this embodiment and Embodiment 1 is that:

[0072] S2. Copper Plating: The gear body is copper plated. After copper plating, the beeswax coating on the teeth is cleaned off. The copper plating process involves placing the alloy gear in an electroplating tank, adding an electroplating solution containing 120 g / L hydroxyethylidene diphosphonic acid and 60 g / L copper sulfate, controlling the temperature at 40°C, and setting the cathode current density to 2.5 A / dm³. 2 The copper plating thickness is 80μm. After the copper plating is completed, the teeth of the alloy gear and the copper-plated gear body are cleaned with 80℃ hot water until the beeswax coating on the teeth is completely removed.

[0073] Example 12

[0074] The difference between this embodiment and Embodiment 1 is that:

[0075] S3. Nitriding: Nitriding is performed on the teeth. After nitriding, beeswax is applied to the teeth again, with three even layers to fully cover the entire tooth. Depending on the specific part of the tooth, the thickness of each layer of beeswax is as follows: 10μm for tooth surface 1, 5μm for tooth root 2, and 5μm for tooth tip 3.

[0076] Example 13

[0077] The difference between this embodiment and Embodiment 1 is that:

[0078] S3. Nitriding: Nitriding is performed on the teeth. After nitriding, beeswax is applied to the teeth again, with 5 layers applied evenly to fully cover the entire tooth. Depending on the specific part of the tooth, the thickness of each layer of beeswax is as follows: 20μm for tooth surface 1, 15μm for tooth root 2, and 10μm for tooth tip 3.

[0079] Example 14

[0080] The difference between this embodiment and Embodiment 1 is that:

[0081] The nitriding process involves: loading the alloy gear into the nitriding furnace, injecting nitrogen gas to purge the air from the furnace, then heating the furnace to 500°C and injecting ammonia gas at a rate of 5 m / s. 3 The injection rate is maintained at 5 h for 5 h, then increased to 540℃. The ammonia injection rate is reduced to 60% of the initial injection rate and maintained for 3 h. The temperature is then increased to 540℃, ammonia injection is stopped, and nitrogen is injected at a rate of 1 m / s². 3 The furnace is heated to 100°C for 2 hours, then cooled down with the furnace while nitrogen is continuously introduced until the temperature drops below 100°C. The nitrided layer is 0.2 μm thick.

[0082] Example 15

[0083] The difference between this embodiment and Embodiment 1 is that:

[0084] The nitriding process involves: loading the alloy gear into the nitriding furnace, injecting nitrogen gas to purge the air from the furnace, then heating the furnace to 530°C and injecting ammonia gas at a rate of 8 m / s. 3 The ammonia injection rate is maintained at 10 h for 10 h, then increased to 560℃, the ammonia injection rate is reduced to 80% of the initial injection rate, and maintained at 10 h for 6 h. Then the temperature is increased to 560℃, ammonia injection is stopped, and nitrogen is injected at an injection rate of 3 m / s. 3The furnace is heated to 4 hours and then cooled down with the furnace. Nitrogen gas is continuously introduced until the temperature drops below 100°C. The nitrided layer is 0.3 μm thick.

[0085] Example 16

[0086] The difference between this embodiment and Embodiment 1 is that:

[0087] S4. Copper Removal: The gear body is subjected to copper removal treatment. The steps for copper removal treatment are as follows: place the alloy gear in a 10% nitric acid solution and soak it at room temperature for 60 seconds. After taking it out, rinse it with deionized water. Then soak it in a 3% sodium carbonate solution for 5 minutes. After taking it out, rinse it with deionized water and dry it.

[0088] Example 17

[0089] The difference between this embodiment and Embodiment 1 is that:

[0090] S4. Copper Removal: The gear body is subjected to copper removal treatment. The steps for copper removal treatment are as follows: place the alloy gear in a 15% nitric acid solution and soak it at room temperature for 10 seconds. After taking it out, rinse it with deionized water. Then soak it in a 5% sodium carbonate solution for 2 minutes. After taking it out, rinse it with deionized water and dry it.

[0091] Experimental Example

[0092] I. Test Background and Purpose

[0093] This test aims to evaluate the fatigue life performance of gears optimized by the method of this invention under specific working conditions. By comparing the data before and after the improvement, the effectiveness of the improvement measures is quantitatively verified.

[0094] II. Detailed Description of Test Conditions

[0095] The test simulated typical working conditions of gears in practical applications, with the following specific parameters:

[0096] Load conditions:

[0097] Reprinted: 150N is considered a medium to light load, suitable for evaluating the durability of gears under high cycle counts, rather than ultimate strength.

[0098] Speed ​​conditions:

[0099] Medium speed: 80–150 rpm. At this speed, the gear's lubrication condition, dynamic load, and thermal load are all within a relatively stable range, which can well reflect its long-term fatigue performance.

[0100] Testing standards:

[0101] The test follows the standard test methods for gear contact fatigue (pitting) and bending fatigue (tooth breakage), and is conducted by continuous operation on a closed power flow test bench until the gear shows signs of failure, such as pitting area exceeding the standard or tooth breakage.

[0102] III. Performance Baseline Before Improvement

[0103] Before any improvements were made, the gear exhibited the following life characteristics under the stated operating conditions:

[0104] Contact fatigue life: approximately 5 × 10 7 change;

[0105] Contact fatigue mainly refers to the formation of microcracks on the surface or subsurface of the tooth surface 1 under cyclic contact stress, which gradually expand and cause material spalling, forming "pitting" or "pockmarks".

[0106] Bending fatigue life: approximately 2 to 3 × 10 7 change

[0107] Bending fatigue mainly refers to the cracks that form at the root of the gear tooth under cyclic bending stress, eventually leading to tooth fracture.

[0108] IV. Improved performance

[0109] After implementing targeted improvement measures, the fatigue life of the gears was significantly improved:

[0110] Contact fatigue life: doubled

[0111] Specific figures: From 5×10 before improvement 7 Upgrade to ≥1.0×10 8 change.

[0112] Significance: Doubling fatigue life means that the gear's resistance to pitting is greatly enhanced. This is due to the increased surface hardness, smoother tooth surface roughness, and effective tooth surface profile modification, which reduces the peak contact stress and the risk of micropitting on the tooth surface.

[0113] Bending fatigue life: increased to approximately 2.5 times.

[0114] Specific values: From 2 to 3 × 10 before improvement 7 The efficiency was increased to 5.0–7.5 × 10⁻⁶. 7 change.

[0115] Significance: A 2.5-fold improvement is a huge leap, especially for the previously weak link, which shows that the improvement measures have effectively enhanced the strength of tooth root 2.

[0116] V. Overall Summary

[0117] Significant improvements have been achieved: the protection of the beeswax layer significantly increases the contact fatigue life and bending fatigue life of gears, by 2 times and 2.5 times respectively. This greatly enhances the reliability and durability of the product.

Claims

1. A method for improving the fatigue resistance of alloy gears by protecting them with beeswax, characterized in that, Includes the following steps: S1. Coating with beeswax: Take the alloy gear to be copper-plated and nitrided, the alloy gear includes teeth located at the edge and gear body, coat the teeth with beeswax, apply 3 to 5 layers evenly to fully cover the entire teeth; S2, Copper plating: The gear body is copper plated, and after the copper plating is completed, the beeswax coating on the teeth is cleaned off. S3, Nitriding: Nitriding is performed on the teeth. After nitriding, beeswax is applied to the teeth again, with 3 to 5 layers applied evenly to fully cover the entire teeth. S4. Copper Removal: The gear body is subjected to copper removal treatment.

2. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 1, characterized in that, In S1 and S3, depending on the specific part of the tooth, the coating thickness of each layer of beeswax is as follows: tooth surface (1) 10-20 μm, tooth root (2) 5-15 μm, tooth tip (3) 5-10 μm.

3. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 1, characterized in that, Before proceeding with S1, the alloy gear is pretreated as follows: First, the alloy gear is immersed in an alkaline degreasing bath for 5-10 minutes, then immersed in an acid pickling bath for 5-10 minutes. After removal, it is rinsed with deionized water 1-2 times and then dried.

4. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 3, characterized in that, The alkaline degreasing bath solution, by weight, comprises 20-40 parts sodium hydroxide, 20-30 parts sodium carbonate, 10-20 parts trisodium phosphate, 5-10 parts sodium silicate, and 1-5 parts surfactant.

5. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 3, characterized in that, The pickling solution is hydrochloric acid with a mass concentration of 15-20%.

6. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 1, characterized in that, In step S2, the copper plating process involves placing the alloy gear in an electroplating tank, adding an electroplating solution comprising 80–120 g / L hydroxyethylidene diphosphonic acid and 40–60 g / L copper sulfate, controlling the temperature at 40–55°C, and setting the cathode current density to 1–2.5 A / dm³. 2 The copper plating thickness is 40-80μm.

7. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 6, characterized in that, In step S2, after copper plating is completed, the teeth of the alloy gear and the copper-plated gear body are cleaned with hot water at 60-80°C until the beeswax coating on the teeth is completely removed.

8. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 1, characterized in that, In S3, the nitriding process involves: loading the alloy gear into a nitriding furnace, injecting nitrogen gas to purge the air from the furnace, then heating the furnace to 500–530°C, injecting ammonia gas at a rate of 5–8 m / s. 3 The injection rate is maintained at 5-10 h for 5-10 h, then increased to 540-560℃. The ammonia injection rate is reduced to 60-80% of the initial injection rate, and maintained at this temperature for 3-6 h. The temperature is then increased to 540-560℃, ammonia injection is stopped, and nitrogen is injected at a rate of 1-3 m / s. 3 The furnace is heated to a constant temperature for 2-4 hours, then cooled down with the furnace while nitrogen is continuously introduced until the temperature drops below 100°C. The nitrided layer thickness is 0.2-0.3 μm.

9. The method for improving the fatigue resistance of alloy gears with beeswax protection according to claim 1, characterized in that, In S4, the copper removal process is as follows: the alloy gear is placed in a nitric acid solution with a mass concentration of 10-15% and immersed at room temperature for 10-60 seconds. After removal, it is rinsed with deionized water and then immersed in a sodium carbonate solution with a mass concentration of 3-5% for 2-5 minutes. After removal, it is rinsed with deionized water and dried.

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