Preparation method of high-precision small gear assembly

Abstract

The invention discloses a preparation method of a high-precision small gear assembly, which comprises the following steps: S1, selecting metal powder, mixing the metal powder with a high-molecular binder in proportion, mixing and uniformly preparing a granulation feed, and finally performing quality inspection on the feed to ensure that the feed is suitable for a subsequent forming process; s2, after the granulation feed is added into an injection molding machine, temperature and pressure parameters are adjusted, it is ensured that the material uniformly flows into a mold, the high-precision mold is used, the dimensional tolerance is controlled within + / -3 micrometers, the material fluidity needs to be kept in the injection process to prevent defects, the mold is cooled after injection is completed, and the material is obtained; the gear manufacturing precision can be improved, the surface smoothness is improved, flaws are reduced, it is guaranteed that the product dimensional tolerance meets the national standard grade requirement, meanwhile, the defects and deformation of a finished product are reduced through strict process control, it is guaranteed that a gear assembly has the longer service life and the higher performance stability, and the gear assembly is suitable for batch high-precision manufacturing.

Description

Technical Field

[0001] The invention relates to the technical field of gear components, and in particular to a method for preparing a high-precision small gear component. Background Art

[0002] High-precision small gear components play an important role in the field of modern science and technology, especially in precision equipment such as drones and robots. As the core components of power transmission and motion control, gear components directly affect the operating efficiency, accuracy and stability of the equipment. The flight control of drones, the precise positioning of robot joints, and the automatic execution of complex tasks all rely on the stable operation and high-precision transmission of gear components.

[0003] However, the current traditional small gear components still have significant defects in some aspects, which limit their performance in high-end applications. First, in the traditional manufacturing process, the dimensional tolerance control of the gear is not precise enough, and it is usually difficult to meet the high precision requirements in the micron range, resulting in the gear meshing is not smooth enough, affecting the operating efficiency of the equipment.

[0004] Secondly, the surface treatment process is not perfect, and there may be burrs or protrusions on the gear surface, which not only increases friction but also shortens the service life of the gear. In addition, dimensional deviations or deformations caused by improper process control often occur during the manufacturing process, further affecting the overall performance and stability of the gear assembly.

[0005] In view of the above problems, we have introduced a method for preparing high-precision small gear components. Summary of the invention

[0006] The invention discloses a method for preparing a high-precision small gear assembly, aiming to solve the technical problems in the background technology.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] A method for preparing a high-precision small gear assembly comprises the following steps:

[0009] S1. After selecting the metal powder, mix it with the polymer binder in proportion, knead and evenly prepare it into granulation feed, and finally check the quality of the feed to ensure that it is suitable for the subsequent molding process;

[0010] The step S1 can be refined as follows:

[0011] S11, select metal powder, preferably 17-4PH stainless steel or 420 stainless steel, and ensure that its particle size is within the range of d10 of 4.8 μm, d50 of 11 μm, and d90 of 20 μm;

[0012] S12, mixing the metal powder with 8%-10% of a polymer binder in a weight ratio, wherein the binder may be a combination of polyoxymethylene, polyethylene and polypropylene;

[0013] S13, mixing the mixture in an internal mixer at a temperature of 180° C. to 190° C. for 2 to 3 hours until a uniform mixture is formed;

[0014] S14, granulating the kneaded mixture through a granulating device, and the obtained granules are used as feed for injection molding;

[0015] S15. The obtained granulation feed should be quality checked to ensure uniform particle size and meet the molding process requirements.

[0016] S2. After adding the granulated feed to the injection molding machine, adjust the temperature and pressure parameters to ensure that the material flows evenly into the mold. Use high-precision molds and control the dimensional tolerance within ±3 microns. Maintain the fluidity of the material during the injection process to prevent defects. Cool the mold after injection to ensure that it does not deform when removed, and conduct quality inspection to ensure that there are no defects on the surface of the gear blank;

[0017] The step S2 can be refined as follows:

[0018] S21, adding the granulated feed to the injection molding machine, adjusting the temperature and pressure parameters of the molding machine to ensure that the feed can flow into the mold evenly;

[0019] S22. Use high-precision molding dies with a dimensional tolerance within ±3 microns to ensure the final size and accuracy of the gears;

[0020] S23. During the injection molding process, the fluidity should be controlled to avoid uneven material flow leading to molding defects such as bubbles or depressions;

[0021] S24. After the injection is completed, the mold cooling time is maintained appropriately to prevent the gear blank from being deformed when it is taken out;

[0022] S25. After forming is completed, take out the gear blank and conduct surface quality inspection to ensure that there are no significant defects and flash on the surface.

[0023] S3. Perform surface sandblasting on the injection-molded gear blanks. Use polypropylene plastic particles with appropriate particle size to clean the gear surface and tooth grooves. Accurately control the sandblasting time and pressure. After sandblasting, use airflow or a brush to clean the surface to ensure that no impurities remain. Check the surface smoothness to ensure that it meets the requirements of subsequent processes.

[0024] The step S3 can be refined as follows:

[0025] S31, performing surface sandblasting on the injection-molded gear blank, using plastic particles with a particle size of 20-120 meshes for sandblasting;

[0026] S32. During the sandblasting process, polypropylene plastic particles are used to reduce damage to the gear surface and ensure that impurities in the tooth grooves are completely removed;

[0027] S33. The time and pressure of sandblasting must be precisely controlled to ensure that the gear surface is evenly cleaned, especially the residue in the tooth groove;

[0028] S34. After the treatment is completed, use air flow or a brush to clean the surface of the gear blank to ensure that there are no residual impurities;

[0029] S35. After the surface treatment is completed, check the cleanliness and surface smoothness of the gear to determine whether it meets the requirements of subsequent processes.

[0030] S4. Put the gear blank after sandblasting into the degreasing equipment and use nitric acid catalytic method to degrease for 240 to 300 minutes. During this period, the flow of nitric acid is controlled to ensure stability. The degreasing effect is checked regularly to ensure that the binder is completely removed and the surface is not corroded. After degreasing, the gear blank is cleaned and dried to prepare for the subsequent sintering process.

[0031] The step S4 can be refined as follows:

[0032] S41, placing the sandblasted gear blank into a degreasing device, and using a nitric acid catalytic degreasing method, the degreasing time is usually 240 to 300 minutes;

[0033] S42. During the degreasing process, the nitric acid flow rate should be controlled at about 3 grams per minute to ensure the stability of the degreasing process;

[0034] S43. Regularly check the surface condition of the gear blank during the degreasing process to ensure that the adhesive is completely removed and that no corrosion is caused to the gear surface;

[0035] S44, after degreasing is completed, the gear blank is cleaned and dried to prevent residual liquid from affecting the sintering process;

[0036] S45. After the binder on the surface and inside of the gear blank is completely removed, ensure that it can smoothly enter the sintering process.

[0037] S5. Put the degreased gear blank into the sintering furnace, control the sintering temperature between 1280℃ and 1325℃, and set the sintering time to 2 to 3 hours according to the material and size. During the sintering process, avoid heating or cooling too quickly to prevent cracks or deformation. After sintering, slowly cool the gear blank and test its size to ensure that the size change meets the design requirements.

[0038] The step S5 can be refined as follows:

[0039] S51, placing the degreased gear blank into a sintering furnace, and controlling the sintering temperature between 1280°C and 1325°C;

[0040] S52. The sintering time is set according to the material and size of the gear, usually 2 to 3 hours, to ensure that the metal particles are fully sintered;

[0041] S53. Avoid excessive heating or cooling during sintering to prevent cracks or deformation in the gear blank.

[0042] S54. After sintering, the gear blank is slowly cooled in the furnace to prevent uneven cooling from causing structural instability;

[0043] S55. Perform dimensional inspection on the sintered gear blank to ensure that its dimensional change is within the design allowable range.

[0044] S6. Place the sintered gear blank into a special extrusion die for shaping, correct the slight deformation during the sintering process, ensure that the die size strictly matches the design requirements, and set the chamfer so that the gear can enter the die smoothly. Control the pressure and feed speed during shaping to ensure uniform force. After shaping, perform appearance and size inspections, and trim surface burrs if necessary.

[0045] The step S6 can be refined as follows:

[0046] S61, placing the sintered gear blank into a special extrusion die for shaping to correct the slight deformation during the sintering process;

[0047] S62. The cavity size of the shaping mold should strictly match the design size of the gear, and the mold mouth should be chamfered to facilitate the gear to enter the mold;

[0048] S63. During the extrusion shaping process, the pressure and feed speed should be controlled to ensure that the gear blank is evenly stressed in the die;

[0049] S64. After the shaping is completed, the appearance and size of the gear blank are inspected to ensure that its shape and size meet the design requirements;

[0050] S65. If there are still slight burrs on the gear surface after shaping, appropriate subsequent trimming can be carried out.

[0051] S7. According to the precision requirements of the gears, polish the surface, use appropriate tools and materials, and avoid excessive wear to maintain the accuracy of size and shape. After polishing, check the surface finish to ensure that there are no burrs or protrusions. Finally, check the dimensional tolerance of the gears to ensure that they meet the national standard precision requirements. After passing the test, package them and prepare for shipment or market launch.

[0052] The step S7 can be refined as follows:

[0053] S71. According to the accuracy requirements of the gears, use appropriate polishing tools and materials to polish the gear surfaces;

[0054] S72. Avoid excessive wear during polishing to ensure that the size and shape of the gear remain within the design range;

[0055] S73. After polishing, check the surface finish of the gear to ensure there are no obvious burrs or protrusions;

[0056] S74. Dimensional tolerance test of finished gears to ensure that their accuracy meets national standards;

[0057] S75. The gears that have passed the final inspection are packaged and are ready to be shipped out of the factory or put on the market.

[0058] The method for preparing a high-precision small gear assembly provided by the present invention has the following advantages:

[0059] This method ensures that the gears meet high standards in size, surface finish and precision by optimizing the processes of mixing metal powder and polymer binder, injection molding, sandblasting, degreasing, sintering, shaping and polishing. This method can improve the precision of gear manufacturing, enhance surface smoothness and reduce defects, ensure that the product dimensional tolerance meets the national standard grade requirements, and reduce defects and deformation of finished products through strict process control, ensuring that the gear components have a longer service life and higher performance stability, and are suitable for mass-produced high-precision manufacturing. BRIEF DESCRIPTION OF THE DRAWINGS

[0060] Figure 1 The present invention is a schematic diagram of the overall process of a method for preparing a high-precision small gear assembly.

[0061] Figure 2 This is a schematic flow chart of step S1 of a method for preparing a high-precision small gear assembly proposed in the present invention.

[0062] Figure 3 This is a schematic flow chart of step S2 of a method for preparing a high-precision small gear assembly proposed in the present invention.

[0063] Figure 4 This is a schematic flow chart of step S3 of a method for preparing a high-precision small gear assembly proposed in the present invention.

[0064] Figure 5 This is a schematic flow chart of step S4 of a method for preparing a high-precision small gear assembly proposed in the present invention.

[0065] Figure 6This is a schematic flow chart of step S5 of a method for preparing a high-precision small gear assembly proposed in the present invention.

[0066] Figure 7 This is a schematic flow chart of step S6 of a method for preparing a high-precision small gear assembly proposed in the present invention.

[0067] Figure 8 This is a schematic flow chart of step S7 of a method for preparing a high-precision small gear assembly proposed in the present invention. DETAILED DESCRIPTION

[0068] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. The components of the embodiments of the present application usually described and marked in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present application provided in the drawings is not intended to limit the scope of the application claimed for protection, but merely represents the selected embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present application.

[0069] The invention discloses a method for preparing a high-precision small gear assembly.

[0070] Reference Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 , Figure 7 and Figure 8 As shown, a method for preparing a high-precision small gear assembly comprises the following steps:

[0071] S1. After selecting the metal powder, mix it with the polymer binder in proportion, knead and evenly prepare it into granulation feed, and finally check the quality of the feed to ensure that it is suitable for the subsequent molding process;

[0072] The step S1 can be refined as follows:

[0073] S11, select metal powder, preferably 17-4PH stainless steel or 420 stainless steel, and ensure that its particle size is within the range of d10 of 4.8 μm, d50 of 11 μm, and d90 of 20 μm;

[0074] S12, mixing the metal powder with 8%-10% of a polymer binder in a weight ratio, wherein the binder may be a combination of polyoxymethylene, polyethylene and polypropylene;

[0075] S13, mixing the mixture in an internal mixer at a temperature of 180° C. to 190° C. for 2 to 3 hours until a uniform mixture is formed;

[0076] S14, granulating the kneaded mixture through a granulating device, and the obtained granules are used as feed for injection molding;

[0077] S15. The obtained granulation feed should be quality checked to ensure uniform particle size and meet the molding process requirements.

[0078] This embodiment: This step mainly involves mixing, uniformly kneading and granulating the metal powder and the polymer binder.

[0079] First, 17-4PH or 420 stainless steel metal powder with a particle size within a specific range is selected, and then it is mixed with binders such as polyoxymethylene and polyethylene according to weight ratio. After the mixture is kneaded at a high temperature of 180°C to 190°C, a uniform mixture is formed, which is then made into the particles required for injection molding through a granulation device and quality inspection is carried out to ensure that its particle size and uniformity meet the requirements of subsequent processes.

[0080] S2. After adding the granulated feed to the injection molding machine, adjust the temperature and pressure parameters to ensure that the material flows evenly into the mold. Use high-precision molds and control the dimensional tolerance within ±3 microns. Maintain the fluidity of the material during the injection process to prevent defects. Cool the mold after injection to ensure that it does not deform when removed, and conduct quality inspection to ensure that there are no defects on the surface of the gear blank;

[0081] The step S2 can be refined as follows:

[0082] S21, adding the granulated feed to the injection molding machine, adjusting the temperature and pressure parameters of the molding machine to ensure that the feed can flow into the mold evenly;

[0083] S22. Use high-precision molding dies with a dimensional tolerance within ±3 microns to ensure the final size and accuracy of the gears;

[0084] S23. During the injection molding process, the fluidity should be controlled to avoid uneven material flow leading to molding defects such as bubbles or depressions;

[0085] S24. After the injection is completed, the mold cooling time is maintained appropriately to prevent the gear blank from being deformed when it is taken out;

[0086] S25. After forming is completed, take out the gear blank and conduct surface quality inspection to ensure that there are no significant defects and flash on the surface.

[0087] This embodiment: This step is mainly to feed the granulated feed into the injection molding machine and adjust the temperature and pressure parameters to ensure that the material flows evenly into the mold.

[0088] Use high-precision molds to control the gear size tolerance within ±3 microns. During the molding process, the material must maintain good fluidity to avoid defects such as bubbles or dents. After the injection is completed, the mold is properly cooled to prevent the gear blank from deforming. Finally, quality inspection is carried out to ensure that there are no defects or flash on the surface to ensure molding accuracy and quality.

[0089] S3. Perform surface sandblasting on the injection-molded gear blanks. Use polypropylene plastic particles with appropriate particle size to clean the gear surface and tooth grooves. Accurately control the sandblasting time and pressure. After sandblasting, use airflow or a brush to clean the surface to ensure that no impurities remain. Check the surface smoothness to ensure that it meets the requirements of subsequent processes.

[0090] The step S3 can be refined as follows:

[0091] S31, performing surface sandblasting on the injection-molded gear blank, using plastic particles with a particle size of 20-120 meshes for sandblasting;

[0092] S32. During the sandblasting process, polypropylene plastic particles are used to reduce damage to the gear surface and ensure that impurities in the tooth grooves are completely removed;

[0093] S33. The time and pressure of sandblasting must be precisely controlled to ensure that the gear surface is evenly cleaned, especially the residue in the tooth groove;

[0094] S34. After the treatment is completed, use air flow or a brush to clean the surface of the gear blank to ensure that there are no residual impurities;

[0095] S35. After the surface treatment is completed, check the cleanliness and surface smoothness of the gear to determine whether it meets the requirements of subsequent processes.

[0096] This embodiment: This step is mainly performed by sandblasting the gear blank after injection molding.

[0097] Use polypropylene plastic particles with a particle size of 20-120 mesh to clean the gear surface and tooth grooves. By precisely controlling the sandblasting time and pressure, ensure that the gear surface is evenly treated, especially to remove residual impurities in the tooth grooves. After sandblasting, use air flow or brushes to clean the surface to ensure that no impurities remain. Finally, check the surface smoothness and cleanliness to ensure that it meets the requirements of subsequent processes.

[0098] S4. Put the gear blank after sandblasting into the degreasing equipment and use nitric acid catalytic method to degrease for 240 to 300 minutes. During this period, the flow of nitric acid is controlled to ensure stability. The degreasing effect is checked regularly to ensure that the binder is completely removed and the surface is not corroded. After degreasing, the gear blank is cleaned and dried to prepare for the subsequent sintering process.

[0099] The step S4 can be refined as follows:

[0100] S41, placing the sandblasted gear blank into a degreasing device, and using a nitric acid catalytic degreasing method, the degreasing time is usually 240 to 300 minutes;

[0101] S42. During the degreasing process, the nitric acid flow rate should be controlled at about 3 grams per minute to ensure the stability of the degreasing process;

[0102] S43. Regularly check the surface condition of the gear blank during the degreasing process to ensure that the adhesive is completely removed and that no corrosion is caused to the gear surface;

[0103] S44, after degreasing is completed, the gear blank is cleaned and dried to prevent residual liquid from affecting the sintering process;

[0104] S45. After the binder on the surface and inside of the gear blank is completely removed, ensure that it can smoothly enter the sintering process.

[0105] This embodiment: This step is mainly a process of degreasing the gear blank after sandblasting.

[0106] The gear blank is placed in the degreasing equipment and degreasing is carried out by nitric acid catalysis, which usually lasts for 240 to 300 minutes. The nitric acid flow rate is controlled to ensure a stable degreasing process. The degreasing effect is checked regularly to ensure that the binder is completely removed without damaging the gear surface. After degreasing, it is cleaned and dried to prevent residual liquid from affecting the subsequent sintering process and prepare for the next sintering process.

[0107] S5. Put the degreased gear blank into the sintering furnace, control the sintering temperature between 1280℃ and 1325℃, and set the sintering time to 2 to 3 hours according to the material and size. During the sintering process, avoid heating or cooling too quickly to prevent cracks or deformation. After sintering, slowly cool the gear blank and test its size to ensure that the size change meets the design requirements.

[0108] The step S5 can be refined as follows:

[0109] S51, placing the degreased gear blank into a sintering furnace, and controlling the sintering temperature between 1280°C and 1325°C;

[0110] S52. The sintering time is set according to the material and size of the gear, usually 2 to 3 hours, to ensure that the metal particles are fully sintered;

[0111] S53. Avoid excessive heating or cooling during sintering to prevent cracks or deformation in the gear blank.

[0112] S54. After sintering, the gear blank is slowly cooled in the furnace to prevent uneven cooling from causing structural instability;

[0113] S55. Perform dimensional inspection on the sintered gear blank to ensure that its dimensional change is within the design allowable range.

[0114] This embodiment: This step is mainly the sintering process of the gear blank.

[0115] Put the degreased gear blank into the sintering furnace, control the sintering temperature between 1280℃ and 1325℃, and set the sintering time to 2 to 3 hours according to the material and size. During the sintering process, the temperature needs to be raised and lowered slowly to avoid cracks or deformation caused by too fast temperature changes. After sintering, slowly cool the gear blank and finally perform dimensional inspection to ensure that it meets the accuracy and size requirements of the design.

[0116] S6. Place the sintered gear blank into a special extrusion die for shaping, correct the slight deformation during the sintering process, ensure that the die size strictly matches the design requirements, and set the chamfer so that the gear can enter the die smoothly. Control the pressure and feed speed during shaping to ensure uniform force. After shaping, perform appearance and size inspections, and trim surface burrs if necessary.

[0117] The step S6 can be refined as follows:

[0118] S61, placing the sintered gear blank into a special extrusion die for shaping to correct the slight deformation during the sintering process;

[0119] S62. The cavity size of the shaping mold should strictly match the design size of the gear, and the mold mouth should be chamfered to facilitate the gear to enter the mold;

[0120] S63. During the extrusion shaping process, the pressure and feed speed should be controlled to ensure that the gear blank is evenly stressed in the die;

[0121] S64. After the shaping is completed, the appearance and size of the gear blank are inspected to ensure that its shape and size meet the design requirements;

[0122] S65. If there are still slight burrs on the gear surface after shaping, appropriate subsequent trimming can be carried out.

[0123] This embodiment: This step is mainly the shaping process of the gear blank after sintering.

[0124] The gear blank is placed in a special extrusion die for shaping, and the slight deformation during sintering is corrected to ensure that the die size strictly matches the design requirements, and the chamfer is set so that the gear can enter the die smoothly. The pressure and feed speed must be controlled during shaping to ensure that the gear blank is evenly stressed. After shaping, the appearance and size are inspected, and the surface burrs are trimmed if necessary to ensure that the accuracy and appearance of the final product meet the requirements.

[0125] S7. According to the precision requirements of the gears, polish the surface, use appropriate tools and materials, and avoid excessive wear to maintain the accuracy of size and shape. After polishing, check the surface finish to ensure that there are no burrs or protrusions. Finally, check the dimensional tolerance of the gears to ensure that they meet the national standard precision requirements. After passing the test, package them and prepare for shipment or market launch.

[0126] The step S7 can be refined as follows:

[0127] S71. According to the precision requirements of the gears, use appropriate polishing tools and materials to polish the gear surfaces;

[0128] S72. Avoid excessive wear during polishing to ensure that the size and shape of the gear remain within the design range;

[0129] S73. After polishing, check the surface finish of the gear to ensure there are no obvious burrs or protrusions;

[0130] S74. Dimensional tolerance test of finished gears to ensure that their accuracy meets national standards;

[0131] S75. The gears that have passed the final inspection are packaged and are ready to be shipped out of the factory or put on the market.

[0132] This embodiment: This step mainly involves surface polishing using appropriate tools and materials based on the precision requirements of the gears, ensuring that surface defects are removed without affecting the size and shape. After polishing, a finish test is performed to ensure that there are no burrs or protrusions. Finally, a dimensional tolerance test is performed to ensure that the gears meet the national standard precision requirements. Qualified gears are then packaged and prepared for shipment or market launch.

[0133] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. The replacement may be a replacement of a part of the structure, device, method step, or a complete technical solution. Any equivalent replacement or change according to the technical solution and the inventive concept of the present invention shall be covered within the protection scope of the present invention.

Claims

1. A method for preparing a high-precision small gear assembly, characterized in that: The following steps are involved: S1. After selecting the metal powder, mix it with the polymer binder in proportion, knead and evenly prepare it into granulation feed, and finally check the quality of the feed to ensure that it is suitable for the subsequent molding process; S2. After adding the granulated feed to the injection molding machine, adjust the temperature and pressure parameters to ensure that the material flows evenly into the mold. Use high-precision molds and control the dimensional tolerance within ±3 microns. Maintain the fluidity of the material during the injection process to prevent defects. Cool the mold after injection to ensure that it does not deform when removed, and conduct quality inspection to ensure that there are no defects on the surface of the gear blank; S3. Perform surface sandblasting on the injection-molded gear blanks. Use polypropylene plastic particles with appropriate particle size to clean the gear surface and tooth grooves. Accurately control the sandblasting time and pressure. After sandblasting, use airflow or a brush to clean the surface to ensure that no impurities remain. Check the surface smoothness to ensure that it meets the requirements of subsequent processes. S4. Put the gear blank after sandblasting into the degreasing equipment and use nitric acid catalytic method to degrease for 240 to 300 minutes. During this period, the flow of nitric acid is controlled to ensure stability. The degreasing effect is checked regularly to ensure that the binder is completely removed and the surface is not corroded. After degreasing, the gear blank is cleaned and dried to prepare for the subsequent sintering process. S5. Put the degreased gear blank into the sintering furnace, control the sintering temperature between 1280℃ and 1325℃, and set the sintering time to 2 to 3 hours according to the material and size. During the sintering process, avoid heating or cooling too quickly to prevent cracks or deformation. After sintering, slowly cool the gear blank and test its size to ensure that the size change meets the design requirements. S6. Place the sintered gear blank into a special extrusion die for shaping, correct the slight deformation during the sintering process, ensure that the die size strictly matches the design requirements, and set the chamfer so that the gear can enter the die smoothly. Control the pressure and feed speed during shaping to ensure uniform force. After shaping, perform appearance and size inspections, and trim surface burrs if necessary. S7. According to the precision requirements of the gears, polish their surfaces, use appropriate tools and materials, and avoid excessive wear to maintain the accuracy of size and shape. After polishing, check the surface finish to ensure there are no burrs or protrusions. Finally, check the dimensional tolerance of the gears to ensure that they meet the national standard precision requirements. After passing the test, package them and prepare for shipment or market launch.

2. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S1 can be refined as follows: S11, select metal powder, preferably 17-4PH stainless steel or 420 stainless steel, and ensure that its particle size is within the range of d10 of 4.8 μm, d50 of 11 μm, and d90 of 20 μm; S12, mixing the metal powder with 8%-10% of a polymer binder according to a weight ratio, wherein the binder may be a combination of polyoxymethylene, polyethylene and polypropylene; S13, mixing the mixture in an internal mixer at a temperature of 180° C. to 190° C. for 2 to 3 hours until a uniform mixture is formed; S14, granulating the kneaded mixture through a granulating device, and the obtained granules are used as feed for injection molding; S15. The obtained granulation feed should be quality checked to ensure uniform particle size and meet the molding process requirements.

3. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S2 can be refined as follows: S21, adding the granulated feed to the injection molding machine, adjusting the temperature and pressure parameters of the molding machine to ensure that the feed can flow into the mold evenly; S22. Use high-precision molding dies with a dimensional tolerance within ±3 microns to ensure the final size and accuracy of the gears; S23. During the injection molding process, the fluidity should be controlled to avoid uneven material flow leading to molding defects such as bubbles or depressions; S24. After the injection is completed, the mold cooling time is maintained appropriately to prevent the gear blank from being deformed when it is taken out; S25. After forming is completed, take out the gear blank and conduct surface quality inspection to ensure that there are no significant defects and flash on the surface.

4. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S3 can be refined as follows: S31, performing surface sandblasting on the injection-molded gear blank, using plastic particles with a particle size of 20-120 meshes for sandblasting; S32. During the sandblasting process, polypropylene plastic particles are used to reduce damage to the gear surface and ensure that impurities in the tooth grooves are completely removed; S33. The time and pressure of sandblasting must be precisely controlled to ensure that the gear surface is evenly cleaned, especially the residue in the tooth groove; S34. After the treatment is completed, use air flow or a brush to clean the surface of the gear blank to ensure that there are no residual impurities; S35. After the surface treatment is completed, check the cleanliness and surface smoothness of the gear to determine whether it meets the requirements of subsequent processes.

5. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S4 can be refined as follows: S41, placing the sandblasted gear blank into a degreasing device, and using a nitric acid catalytic degreasing method, the degreasing time is usually 240 to 300 minutes; S42. During the degreasing process, the nitric acid flow rate should be controlled at about 3 grams per minute to ensure the stability of the degreasing process; S43. Regularly check the surface condition of the gear blank during the degreasing process to ensure that the adhesive is completely removed and that no corrosion is caused to the gear surface; S44, after degreasing is completed, the gear blank is cleaned and dried to prevent residual liquid from affecting the sintering process; S45. After the binder on the surface and inside of the gear blank is completely removed, ensure that it can smoothly enter the sintering process.

6. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S5 can be refined as follows: S51, placing the degreased gear blank into a sintering furnace, and controlling the sintering temperature between 1280°C and 1325°C; S52. The sintering time is set according to the material and size of the gear, usually 2 to 3 hours, to ensure that the metal particles are fully sintered; S53. Avoid excessive heating or cooling during sintering to prevent cracks or deformation in the gear blank. S54. After sintering is completed, the gear blank is slowly cooled in the furnace to prevent uneven cooling from causing structural instability; S55. Perform dimensional inspection on the sintered gear blank to ensure that its dimensional change is within the design allowable range.

7. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S6 can be refined as follows: S61, placing the sintered gear blank into a special extrusion die for shaping to correct the slight deformation during the sintering process; S62. The cavity size of the shaping mold should strictly match the design size of the gear, and the mold mouth should be chamfered to facilitate the gear to enter the mold; S63. During the extrusion shaping process, the pressure and feed speed should be controlled to ensure that the gear blank is evenly stressed in the die; S64. After the shaping is completed, the appearance and size of the gear blank are inspected to ensure that its shape and size meet the design requirements; S65. If there are still slight burrs on the gear surface after shaping, appropriate subsequent trimming can be carried out.

8. The method for preparing a high-precision small gear assembly according to claim 1, characterized in that: The step S7 can be refined as follows: S71. According to the accuracy requirements of the gears, use appropriate polishing tools and materials to polish the gear surfaces; S72. Avoid excessive wear during polishing to ensure that the size and shape of the gear remain within the design range; S73. After polishing, check the surface finish of the gear to ensure there are no obvious burrs or protrusions; S74. Dimensional tolerance test of finished gears to ensure that their accuracy meets national standards; S75. The gears that have passed the final inspection are packaged and are ready to be shipped out of the factory or put on the market.

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