Surface oxidation treatment device for high-airtightness powder metallurgy product

Abstract

The invention relates to the technical field of oxidation treatment of powder metallurgy products, and discloses a surface oxidation treatment device for high-airtightness powder metallurgy products, which comprises a pretreatment mechanism, one end of the pretreatment mechanism is fixedly connected with a steam treatment furnace, and a conveying mechanism is mounted between the pretreatment mechanism and the steam treatment furnace; a powder metallurgy product assembly is conveyed on the conveying mechanism; the pretreatment mechanism comprises a first machine body, an outer shell, a ventilation shell, a vacuum assembly and a first steam assembly, the outer shell is connected to the upper side of the first machine body, and the ventilation shell is fixedly connected to the inner side of the outer shell. According to the active pretreatment method, the closed cavity is vacuumized firstly to form negative pressure, then low-temperature steam is injected, and the steam is forcibly and rapidly permeated into all the deep holes of the powder metallurgy product through the pressure difference. The problem of non-uniform permeation caused by obstruction of residual air in pores in traditional direct steam treatment is fundamentally solved.

Description

Technical Field

[0001] This invention relates to the field of oxidation treatment technology for powder metallurgy products, specifically to a surface oxidation treatment device for high airtight powder metallurgy products. Background Technology

[0002] High-airtightness powder metallurgy products (such as gears) inevitably contain sintered pores. Therefore, surface oxidation treatment is necessary to form a dense oxide film (such as Fe3O4) on the inner wall of these pores to physically seal them, thus meeting stringent requirements such as high pressure, vacuum, or leak-proof conditions. Steam treatment is the mainstream process for achieving this goal.

[0003] However, existing steam treatment equipment and processes still have significant drawbacks: First, traditional single-furnace systems lack effective pretreatment before processing, and air in the pores inside the parts hinders the rapid and uniform penetration of initial steam, resulting in poor oxide film growth in the core of complex or thick-walled parts, affecting the uniformity of airtightness. Second, most treatment furnaces use overall temperature control, resulting in poor uniformity of the temperature and steam concentration fields within the furnace. For continuous production, it is impossible to independently and precisely control different stages of the oxidation reaction (heating, isothermal reaction, cooling), leading to unstable reaction efficiency and film quality. Summary of the Invention

[0004] The purpose of this invention is to provide a surface oxidation treatment device for high airtightness powder metallurgy products to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: a surface oxidation treatment device for high airtightness powder metallurgy products, comprising a pretreatment mechanism, one end of which is fixedly connected to a steam treatment furnace, and a conveying mechanism is installed between the pretreatment mechanism and the steam treatment furnace, on which powder metallurgy product components are conveyed. The pretreatment mechanism includes a main body, an outer shell, a ventilation shell, a vacuum assembly, and a steam assembly. The outer shell is fixedly connected to the upper side of the main body, the ventilation shell is fixedly connected to the inner side of the outer shell, the vacuum assembly is fixedly connected to the upper side of the outer shell, and the steam assembly is provided on the inner side of the ventilation shell. The steam treatment furnace includes a second body, a furnace shell, a rapid heating section, a constant temperature reaction section, and a slow cooling section. One end of the first body is fixedly connected to the second body, and the furnace shell is fixedly connected to the upper side of the second body. The rapid heating section, the constant temperature reaction section, and the slow cooling section are arranged sequentially on the inner side of the furnace shell. The powder metallurgy product components are conveyed through the conveying mechanism to pass through the pretreatment mechanism, the rapid heating section, the constant temperature reaction section, and the slow cooling section in sequence, so as to realize pretreatment and multi-stage zoned oxidation.

[0006] Furthermore, the vacuum assembly includes a vacuum pump and a vacuum tube. The vacuum pump is fixedly connected to the upper side of the outer casing, and the upper side of the vacuum pump is connected to the vacuum tube. The vacuum tube is connected to the inner side of the outer casing, and the ventilation housing has evenly distributed ventilation slots.

[0007] Furthermore, the steam assembly includes a steam main pipe, a steam branch pipe, and a steam nozzle. The steam main pipe is disposed inside the ventilation housing and penetrates one side of the ventilation housing and the outer housing. The steam main pipe is connected to a uniformly distributed steam branch pipe and is disposed inside the ventilation housing. The lower side of the steam main pipe and the steam branch pipe is connected to a uniformly distributed steam nozzle and is disposed inside the ventilation housing.

[0008] Furthermore, the conveying mechanism includes a motor, a sprocket, a sprocket, a rotating shaft, a sprocket, a bearing housing, and a chain. The motor is fixedly connected to the inner side of the machine body, and the output end of the motor is fixedly connected to the sprocket. Two sets of bearing housings are fixedly connected to the upper side of both the machine body and the machine body. A rotating shaft is rotatably connected to the inner side of the two sets of bearing housings. A sprocket is fixedly mounted on the rotating shaft. A chain is meshed between the two sets of sprockets. A support rail is fixedly connected to the upper side of both the machine body and the machine body. The chain is in contact with the support rail, and a chain is meshed between the sprocket and the sprocket.

[0009] Furthermore, the powder metallurgy product assembly includes a mounting frame and metal products. The mounting frame is conveyed on the upper side of the chain, and the mounting frame is fitted with evenly distributed metal products.

[0010] Powder metallurgy products (metal products) to be processed are regularly placed on the mounting rack, forming powder metallurgy product assemblies. The conveying mechanism is activated; the motor drives sprocket one, which in turn drives sprocket two and a series of conveyor chains consisting of sprocket three, chain one, and a rotating shaft via chain two. The bottom of the mounting rack engages with chain one, and guided by the support rail, the products are smoothly and sequentially fed into the pretreatment mechanism and the subsequent steam treatment furnace. Once the mounting frame enters the sealed chamber of the pretreatment mechanism (consisting of the main body, outer shell, and ventilation shell), the closing assembly located at the inlet side and the connection between the outer shell and the treatment furnace shell is activated. A cylinder pushes the closing plate down the track plate, sealing the chamber completely. Immediately afterward, the vacuum assembly operates, and the vacuum pump extracts gas from the chamber through the vacuum pipe, creating negative pressure inside and outside the product's pores. Next, the steam assembly is activated, and saturated or low-temperature superheated steam is distributed from the main steam pipe through the steam distributor and uniformly injected into the negative pressure chamber through the steam nozzles. Driven by the pressure difference, the steam is forced and rapidly injected into all the pores deep within the product, completing the penetration and initial wetting reaction, laying a uniform foundation for subsequent main oxidation. Ventilation slots on the ventilation shell ensure uniform airflow distribution. Furthermore, the rapid heating section, the constant temperature reaction section, and the slow cooling section all include a heating mechanism and a second steam assembly. The heating mechanism includes a protective shell, a second motor, a belt, a drive shaft, fan blades, a heating chamber, a support frame, and a heating tube. The heating chamber is fixedly connected to the inner side of the furnace shell, and the protective shell is fixedly connected to the upper side of the second body. The second motor is installed inside the protective shell, and two sets of pulleys are installed inside the protective shell. The output end of the second motor is fixedly connected to one set of pulleys, and the other set of pulleys... A drive shaft is fixedly connected to the lower side, and a fan blade is fixedly connected to the lower side of the drive shaft. The two sets of pulleys are connected by belt drive. Two layers are provided inside the heating chamber. The fan blade is located in the upper layer. A support frame is fixedly connected to the inner side of the lower layer. Multiple sets of heating tubes are fixedly connected to the upper side of the support frame. A fixed plate is fixedly connected to the upper side of the heating chamber. The drive shaft is rotatably connected to the fixed plate. The motor is fixedly connected to the fixed plate. Evenly distributed through holes are opened on the lower side of the layer where the fan blade is located.

[0011] Furthermore, the second steam assembly includes a second steam main pipe, a second steam nozzle, and a second steam branch pipe. The second steam main pipe is located inside the heating chamber and below the lower interlayer. The second steam main pipe penetrates the heating chamber and one side of the furnace shell. The second steam main pipe is connected to a uniformly distributed second steam branch pipe. The second steam main pipe and the second steam branch pipe are connected to a uniformly distributed second steam nozzle on their lower sides. The second steam branch pipe and the second steam nozzle are both located inside the heating chamber.

[0012] The pre-treated products are fed into the steam treatment furnace by a conveyor mechanism. The furnace body consists of a furnace shell, and its interior is divided into three independent temperature and steam control reaction zones along the conveying direction: a rapid heating zone, a constant temperature reaction zone, and a slow cooling zone.

[0013] Rapid Heating Section: In this section, the second motor of the heating mechanism starts, driving the drive shaft and fan blades to rotate at high speed via belt drive. Simultaneously, the heating tubes on the support frame are energized and heat up. The fan blades forcefully blow hot air flowing through the heating tubes onto the products passing below, rapidly and evenly heating them to the reaction temperature. The second steam assembly operates synchronously; steam from the main steam pipe second is injected through the steam branch pipe second and into the steam nozzle second, providing the atmosphere required for the oxidation reaction. The goal of this section is to rapidly exceed the reaction threshold temperature.

[0014] Constant Temperature Reaction Zone: The product enters this core reaction zone. The heating mechanism in this zone aims to maintain a precise constant temperature. Motor 2 and the heating element work in concert with feedback from temperature and humidity sensors to ensure minimal temperature fluctuations. A continuous and stable steam supply allows for full reaction between the steam and the surface and pore walls of the iron-based powder metallurgy product, generating a uniform and dense Fe3O4 oxide film. The heating mechanisms and steam components in each zone can be independently adjusted.

[0015] Slow cooling section: After the oxidation reaction is complete, the product enters this zone. The heating tube power is reduced or turned off in this zone, and the cooling airflow rate is mainly adjusted by controlling the fan blade speed, so that the product cools down slowly and evenly, avoiding stress cracks in the oxide film caused by rapid cooling and ensuring the integrity of the film layer; Furthermore, a closing assembly is installed on the inlet side of the outer shell, the outlet side of the processing furnace shell, and the connection between the outer shell and the processing furnace shell. The closing assembly includes a mounting frame, a cylinder, a closing plate, and a track plate. The cylinder is fixedly connected to the inner side of the mounting frame, the closing plate is fixedly connected to the lower output end of the cylinder, and the track plate is slidably connected to the outer side of the closing plate.

[0016] Furthermore, a temperature and humidity sensor is installed inside the heating chamber, and the temperature and humidity sensor penetrates one side of the heating chamber and the furnace shell.

[0017] Compared with the prior art, the present invention provides a surface oxidation treatment device for high airtightness powder metallurgy products, which has the following beneficial effects: 1. This invention creates a negative pressure by first evacuating a sealed chamber, then injecting low-temperature steam. The pressure difference forces the steam to penetrate rapidly and completely into all the pores of the powder metallurgy product. This proactive pretreatment method of "exhausting air first, then wetting" fundamentally solves the problem of uneven penetration caused by residual air in the pores during traditional direct steam treatment. In particular, it ensures that even the core of complex structures or thick-walled parts achieves uniform wetting and initial oxidation, laying a solid foundation for the subsequent formation of a dense and uniform oxide film, and directly improving the airtightness, uniformity, and reliability of the final product.

[0018] 2. This invention clearly divides the processing furnace into a "rapid heating section," a "constant temperature reaction section," and a "slow cooling section," allowing for the setting and independent control of the optimal temperature profile, steam concentration, and atmosphere flow field for each stage (achieved through independent heating mechanisms and steam components for each zone). For example, the rapid heating section can quickly raise the product to the reaction temperature to improve efficiency; the constant temperature reaction section can maintain extremely high temperature uniformity to ensure consistent oxide film quality and thickness; and the slow cooling section can control the cooling rate to eliminate thermal stress and prevent film cracking. This segmented design overcomes the shortcomings of traditional single-zone furnaces, which have limited operating conditions and struggle to achieve optimal conditions for each reaction stage, thereby improving the overall density, adhesion, and product yield of the oxide film. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the present invention; Figure 2 For the present invention Figure 1 Enlarged 3D structural diagram at point A; Figure 3 This is a three-dimensional structural schematic diagram of the present invention from another angle; Figure 4 This is a three-dimensional structural diagram of the pretreatment mechanism of the present invention after partial cross-section; Figure 5 This is a three-dimensional structural diagram of the pretreatment mechanism of the present invention; Figure 6 This is a three-dimensional structural diagram of the conveying mechanism of the present invention; Figure 7 This is a schematic diagram of the internal three-dimensional structure of the pretreatment mechanism of the present invention; Figure 8 For the present invention Figure 7 A magnified 3D structural diagram at point B in the middle; Figure 9 This is a three-dimensional structural diagram of the steam treatment furnace of the present invention; Figure 10 This is a cross-sectional three-dimensional structural diagram of the steam treatment furnace of the present invention; Figure 11 This is a schematic diagram of the internal three-dimensional structure of the steam treatment furnace of the present invention; Figure 12 For the present invention Figure 11 Enlarged 3D structural diagram at point C; Figure 13 This is a three-dimensional structural diagram of the closure component of the present invention.

[0020] In the diagram: 1. Pretreatment mechanism; 11. Main body 1; 12. Outer shell; 13. Ventilation shell; 14. Vacuum assembly; 141. Vacuum pump; 142. Vacuum pipe; 15. Steam assembly 1; 151. Steam main pipe 1; 152. Steam branch pipe 1; 153. Steam nozzle 1; 2. Steam treatment furnace; 21. Main body 2; 22. Furnace shell; 23. Rapid heating section; 24. Constant temperature reaction section; 25. Slow cooling section; 3. Powder metallurgy product assembly; 31. Loading rack; 32. Metal product; 4. Conveying mechanism; 41. Electric... 42. Sprocket 1; 43. Sprocket 2; 44. Rotating shaft; 45. Sprocket 3; 46. Bearing housing; 47. Chain 1; 48. Support rail; 5. Heating mechanism; 51. Protective shell; 52. Motor 2; 54. Drive shaft; 55. Fan blade; 56. Heating chamber; 57. Support frame; 58. Heating pipe; 6. Steam assembly 2; 61. Steam main pipe 2; 62. Steam nozzle 2; 63. Steam branch pipe 2; 7. Closing assembly; 71. Mounting bracket; 72. Cylinder; 73. Closing plate; 74. Track plate; 8. Temperature and humidity sensor. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example

[0022] Please see Figures 1-13 A surface oxidation treatment device for high airtight powder metallurgy products includes a pretreatment mechanism 1, a steam treatment furnace 2 fixedly connected to one end of the pretreatment mechanism 1, a conveying mechanism 4 installed between the pretreatment mechanism 1 and the steam treatment furnace 2, and a powder metallurgy product assembly 3 conveyed on the conveying mechanism 4. The pretreatment mechanism 1 includes a body 11, an outer shell 12, a ventilation shell 13, a vacuum assembly 14, and a steam assembly 15. The outer shell 12 is fixedly connected to the upper side of the body 11, the ventilation shell 13 is fixedly connected to the inner side of the outer shell 12, the vacuum assembly 14 is fixedly connected to the upper side of the outer shell 12, and the steam assembly 15 is provided on the inner side of the ventilation shell 13. The steam treatment furnace 2 includes a second body 21, a furnace shell 22, a rapid heating section 23, a constant temperature reaction section 24, and a slow cooling section 25. One end of the first body 11 is fixedly connected to the second body 21, and the furnace shell 22 is fixedly connected to the upper side of the second body 21. The rapid heating section 23, the constant temperature reaction section 24, and the slow cooling section 25 are arranged sequentially on the inner side of the furnace shell 22. The powder metallurgy product assembly 3 is conveyed by the conveying mechanism 4 through the pretreatment mechanism 1, the rapid heating section 23, the constant temperature reaction section 24, and the slow cooling section 25 in sequence to achieve pretreatment and multi-stage zoned oxidation.

[0023] Furthermore, the vacuum assembly 14 includes a vacuum pump 141 and a vacuum tube 142. The vacuum pump 141 is fixedly connected to the upper side of the outer casing 12, and the vacuum tube 142 is connected to the upper side of the vacuum pump 141. The vacuum tube 142 is connected to the inner side of the outer casing 12, and the ventilation housing 13 is provided with evenly distributed ventilation slots.

[0024] Furthermore, the steam assembly 15 includes a steam main pipe 151, a steam branch pipe 152, and a steam nozzle 153. The steam main pipe 151 is disposed inside the ventilation housing 13 and passes through one side of the ventilation housing 13 and the outer housing 12. The steam main pipe 151 is connected to the evenly distributed steam branch pipe 152, which is disposed inside the ventilation housing 13. The lower side of the steam main pipe 151 and the steam branch pipe 152 is connected to the evenly distributed steam nozzle 153, which is disposed inside the ventilation housing 13.

[0025] Furthermore, the transmission mechanism 4 includes a motor 41, a sprocket 42, a sprocket 43, a rotating shaft 44, a sprocket 45, a bearing seat 46, and a chain 47. The motor 41 is fixedly connected to the inner side of the machine body 11, and the sprocket 42 is fixedly connected to the output end of the motor 41. Two sets of bearing seats 46 are fixedly connected to the upper side of both the machine body 11 and the upper side of the machine body 21. The rotating shaft 44 is rotatably connected to the inner side of the corresponding two sets of bearing seats 46. The sprocket 45 is fixedly installed on the rotating shaft 44, and the chain 47 meshes between the corresponding two sets of sprockets 45. The upper side of both the machine body 11 and the machine body 21 is fixedly connected to the support rail 48. The chain 47 is in contact with the support rail 48, and the chain 47 meshes between the sprocket 42 and the sprocket 43.

[0026] Furthermore, the powder metallurgy product assembly 3 includes a mounting frame 31 and metal products 32. The mounting frame 31 is conveyed on the upper side of the chain 47, and the metal products 32 are uniformly distributed on the mounting frame 31.

[0027] The powder metallurgy products 32 to be processed are regularly placed on the mounting frame 31, forming the powder metallurgy product assembly 3. The conveying mechanism 4 is activated, and the motor 41 drives sprocket 42, which in turn drives sprocket 43 and a series of conveyor chains consisting of sprocket 45, chain 47, and rotating shaft 44 via chain 2. The bottom of the mounting frame 31 engages with chain 47, and under the guidance of the support rail 48, the metal is smoothly fed sequentially into the pretreatment mechanism 1 and the subsequent steam treatment furnace 2. When the mounting frame 31 enters the sealed chamber of the pretreatment mechanism 1, which consists of the main body 11, the outer shell 12, and the ventilation shell 13, the closing assembly 7, located at the inlet side and at the connection between the outer shell 12 and the treatment furnace shell 22, is activated. The cylinder 72 pushes the closing plate 73 down along the track plate 74, sealing the chamber completely. Immediately afterward, the vacuum assembly 14 operates, and the vacuum pump 141 extracts gas from the chamber through the vacuum pipe 142, creating a negative pressure inside and outside the pores of the product. Next, the steam assembly 15 is activated, and saturated or low-temperature superheated steam is distributed from the main steam pipe 151 through the steam branch pipe 152 and evenly injected into the negative pressure chamber by the steam nozzle 153. Driven by the pressure difference, the steam is forced and rapidly injected into all the pores deep within the product, completing the penetration and initial wetting reaction, laying a uniform foundation for subsequent main oxidation. The ventilation slots on the ventilation shell 13 ensure uniform airflow distribution. Furthermore, the rapid heating section 23, the constant temperature reaction section 24, and the slow cooling section 25 all include a heating mechanism 5 and a second steam assembly 6. The heating mechanism 5 includes a protective shell 51, a second motor 52, a belt 53, a drive shaft 54, fan blades 55, a heating chamber 56, a support frame 57, and a heating tube 58. The heating chamber 56 is fixedly connected to the inner side of the furnace shell 22, and the protective shell 51 is fixedly connected to the upper side of the second body 21. The second motor 52 is installed inside the protective shell 51, and two sets of pulleys are installed inside the protective shell 51. The output end of the second motor 52 is fixedly connected to one set of pulleys. Another set of pulleys is fixedly connected to a drive shaft 54 ​​on its lower side, and a fan blade 55 is fixedly connected to the lower side of the drive shaft 54. The two sets of pulleys are connected by a belt 53. Two layers are provided inside the heating chamber 56. The fan blade 55 is located in the upper layer. A support frame 57 is fixedly connected to the inner side of the lower layer. Multiple sets of heating tubes 58 are fixedly connected to the upper side of the support frame 57. A fixed plate is fixedly connected to the upper side of the heating chamber 56. The drive shaft 54 ​​is rotatably connected to the fixed plate. The motor 52 is fixedly connected to the fixed plate. The lower side of the layer where the fan blade 55 is located has evenly distributed through holes.

[0028] Furthermore, the steam assembly 26 includes a steam main pipe 261, a steam nozzle 262, and a steam branch pipe 263. The steam main pipe 261 is located inside the heating chamber 56 and below the lower interlayer. The steam main pipe 261 passes through the heating chamber 56 and one side of the furnace shell 22. The steam main pipe 261 is connected to the evenly distributed steam branch pipe 263. The steam nozzle 262 is evenly distributed below the steam main pipe 261 and the steam branch pipe 263. The steam branch pipe 263 and the steam nozzle 262 are both located inside the heating chamber 56.

[0029] The pre-treated products are fed into the steam treatment furnace 2 by the conveyor mechanism 4. The furnace body is composed of a furnace shell 22, and its interior is divided into three independent temperature and steam control reaction zones along the conveying direction: a rapid heating zone 23, a constant temperature reaction zone 24, and a slow cooling zone 25.

[0030] Rapid Heating Section 23: In this section, motor 52 of heating mechanism 5 starts, driving drive shaft 54 ​​and fan blades 55 to rotate at high speed via belt drive. Simultaneously, heating tubes 58 on support frame 57 are energized and heat up. Fan blades 55 forcefully blow hot air flowing through heating tubes 58 onto the product passing below, rapidly and evenly heating it to the reaction temperature. Steam assembly 6 operates synchronously; steam from main steam pipe 61 is injected through steam branch pipe 63 and steam nozzle 62, providing the atmosphere required for the oxidation reaction. The goal of this section is to rapidly exceed the reaction threshold temperature.

[0031] Constant Temperature Reaction Section 24: The product enters this core reaction zone. The heating mechanism in this zone aims to maintain a precise constant temperature. Motor 2 52 and heating element 58 work in concert with feedback from temperature and humidity sensor 8 to ensure minimal temperature fluctuations. A continuous and stable steam supply allows for full reaction between the steam and the surface and pore walls of the iron-based powder metallurgy product, generating a uniform and dense Fe3O4 oxide film. The heating mechanism 5 and steam assembly 6 in each zone can be independently adjusted.

[0032] Slow cooling section 25: After the oxidation reaction is complete, the product enters this zone. In this zone, the power of the heating tube 58 is reduced or turned off, and the cooling airflow rate is mainly adjusted by controlling the speed of the fan blades 55 to allow the product to cool down slowly and evenly, avoiding stress cracks in the oxide film caused by rapid cooling and ensuring the integrity of the film layer; Furthermore, a closing assembly 7 is installed on the inlet side of the outer shell 12, the outlet side of the processing furnace shell 22, and the connection between the outer shell 12 and the processing furnace shell 22. The closing assembly 7 includes a mounting frame 71, a cylinder 72, a closing plate 73, and a track plate 74. The cylinder 72 is fixedly connected to the inner side of the mounting frame 71, the closing plate 73 is fixedly connected to the lower output end of the cylinder 72, and the track plate 74 is slidably connected to the outer side of the closing plate 73.

[0033] Furthermore, a temperature and humidity sensor 8 is provided inside the heating chamber 56, and the temperature and humidity sensor 8 passes through one side of the heating chamber 56 and the furnace shell 22.

[0034] The specific usage and function of this embodiment are as follows: The powder metallurgy products 32 to be processed are regularly placed on the mounting frame 31, forming the powder metallurgy product assembly 3. The conveying mechanism 4 is activated, and the motor 41 drives sprocket 42, which in turn drives sprocket 43 and a series of conveyor chains consisting of sprocket 45, chain 47, and rotating shaft 44. The bottom of the mounting frame 31 engages with chain 47, and under the guidance of the support rail 48, the metal products are smoothly and sequentially fed into the pretreatment mechanism 1 and the subsequent steam treatment furnace 2.

[0035] When the mounting frame 31 enters the sealed chamber of the pretreatment mechanism 1, which consists of the main body 11, the outer shell 12, and the ventilation shell 13, the closing assembly 7, located at the inlet side and at the connection between the outer shell 12 and the treatment furnace shell 22, is activated. The cylinder 72 pushes the closing plate 73 down along the track plate 74, sealing the chamber completely. Immediately afterward, the vacuum assembly 14 operates, and the vacuum pump 141 extracts gas from the chamber through the vacuum pipe 142, creating a negative pressure inside and outside the pores of the product. Next, the steam assembly 15 is activated, and saturated or low-temperature superheated steam is distributed from the main steam pipe 151 through the steam branch pipe 152 and evenly injected into the negative pressure chamber by the steam nozzle 153. Driven by the pressure difference, the steam is forced and rapidly injected into all the pores deep within the product, completing the penetration and initial wetting reaction, laying a uniform foundation for subsequent main oxidation. The ventilation slots on the ventilation shell 13 ensure uniform airflow distribution.

[0036] The pre-treated products are fed into the steam treatment furnace 2 by the conveyor mechanism 4. The furnace body is composed of a furnace shell 22, and its interior is divided into three independent temperature and steam control reaction zones along the conveying direction: a rapid heating zone 23, a constant temperature reaction zone 24, and a slow cooling zone 25.

[0037] Rapid Heating Section 23: In this section, motor 52 of heating mechanism 5 starts, driving drive shaft 54 ​​and fan blades 55 to rotate at high speed via belt drive. Simultaneously, heating tubes 58 on support frame 57 are energized and heat up. Fan blades 55 forcefully blow hot air flowing through heating tubes 58 onto the product passing below, rapidly and evenly heating it to the reaction temperature. Steam assembly 6 operates synchronously; steam from main steam pipe 61 is injected through steam branch pipe 63 and steam nozzle 62, providing the atmosphere required for the oxidation reaction. The goal of this section is to rapidly exceed the reaction threshold temperature.

[0038] Constant Temperature Reaction Section 24: The product enters this core reaction zone. The heating mechanism in this zone aims to maintain a precise constant temperature. Motor 2 52 and heating element 58 work in concert with feedback from temperature and humidity sensor 8 to ensure minimal temperature fluctuations. A continuous and stable steam supply allows for full reaction between the steam and the surface and pore walls of the iron-based powder metallurgy product, generating a uniform and dense Fe3O4 oxide film. The heating mechanism 5 and steam assembly 6 in each zone can be independently adjusted.

[0039] Slow cooling section 25: After the oxidation reaction is complete, the product enters this zone. In this zone, the power of the heating tube 58 is reduced or turned off, and the cooling airflow rate is mainly adjusted by controlling the speed of the fan blades 55 to allow the product to cool down slowly and evenly, avoiding stress cracks in the oxide film caused by rapid cooling and ensuring the integrity of the film layer.

[0040] After the products are cooled to a safe temperature in the slow cooling section, they move to the outlet via the conveyor mechanism 4. The closing component 7 at the outlet opens under the command of the control system. The receiving rack 31 carries the products that have undergone high-quality oxidation treatment out for unloading. At the same time, new receiving racks 31 can continuously enter the pretreatment mechanism 1, forming an uninterrupted continuous automated production process.

[0041] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A surface oxidation treatment device for high airtight powder metallurgy products, comprising a pretreatment mechanism (1), characterized in that: One end of the pretreatment mechanism (1) is fixedly connected to a steam treatment furnace (2), and a conveying mechanism (4) is installed between the pretreatment mechanism (1) and the steam treatment furnace (2). Powder metallurgy product components (3) are conveyed on the conveying mechanism (4). The pretreatment mechanism (1) includes a main body (11), an outer shell (12), a ventilation shell (13), a vacuum assembly (14), and a steam assembly (15). The outer shell (12) is fixedly connected to the upper side of the main body (11), the ventilation shell (13) is fixedly connected to the inner side of the outer shell (12), the vacuum assembly (14) is fixedly connected to the upper side of the outer shell (12), and the steam assembly (15) is provided on the inner side of the ventilation shell (13). The steam treatment furnace (2) includes a second body (21), a furnace shell (22), a rapid heating section (23), a constant temperature reaction section (24), and a slow cooling section (25). One end of the first body (11) is fixedly connected to the second body (21). The furnace shell (22) is fixedly connected to the upper side of the second body (21). The furnace shell (22) is arranged in sequence on the inner side of the furnace shell (22). The powder metallurgy product assembly (3) is conveyed through the conveying mechanism (4) and passes through the pretreatment mechanism (1), the rapid heating section (23), the constant temperature reaction section (24), and the slow cooling section (25) in sequence to achieve pretreatment and multi-stage zoned oxidation.

2. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 1, characterized in that: The vacuum assembly (14) includes a vacuum pump (141) and a vacuum tube (142). The vacuum pump (141) is fixedly connected to the upper side of the outer shell (12). The upper side of the vacuum pump (141) is connected to the vacuum tube (142). The vacuum tube (142) is connected to the inner side of the outer shell (12). The ventilation housing (13) has evenly distributed ventilation slots.

3. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 1, characterized in that: The steam assembly (15) includes a steam main pipe (151), a steam branch pipe (152), and a steam nozzle (153). The steam main pipe (151) is provided inside the ventilation housing (13). The steam main pipe (151) passes through one side of the ventilation housing (13) and the outer shell (12). The steam main pipe (151) is connected to a uniformly distributed steam branch pipe (152). The steam branch pipe (152) is located inside the ventilation housing (13). The lower side of the steam main pipe (151) and the steam branch pipe (152) is connected to a uniformly distributed steam nozzle (153). The steam nozzle (153) is located inside the ventilation housing (13).

4. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 1, characterized in that: The transmission mechanism (4) includes a motor (41), a sprocket (42), a sprocket (43), a rotating shaft (44), a sprocket (45), a bearing seat (46), and a chain (47). The motor (41) is fixedly connected to the inner side of the machine body (11), and the sprocket (42) is fixedly connected to the output end of the motor (41). Two sets of bearing seats (46) are fixedly connected to the upper side of both the machine body (11) and the upper side of the machine body (21). The inner sides of the two sets of bearing seats (46) are rotatably connected to a rotating shaft (44), and a sprocket three (45) is fixedly installed on the rotating shaft (44). A chain one (47) meshes between the two sets of sprocket three (45). A support rail (48) is fixedly connected to the upper side of the machine body one (11) and the machine body two (21). The chain one (47) is in contact with the support rail (48), and a chain two meshes between the sprocket one (42) and the sprocket two (43).

5. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 4, characterized in that: The powder metallurgy product assembly (3) includes a mounting frame (31) and metal products (32). The mounting frame (31) is conveyed on the upper side of the chain (47), and the metal products (32) are uniformly distributed on the mounting frame (31).

6. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 1, characterized in that: The rapid heating section (23), constant temperature reaction section (24), and slow cooling section (25) all include a heating mechanism (5) and a second steam assembly (6). The heating mechanism (5) includes a protective shell (51), a second motor (52), a belt (53), a drive shaft (54), a fan blade (55), a heating chamber (56), a support frame (57), and a heating tube (58). The heating chamber (56) is fixedly connected to the inner side of the furnace shell (22). The protective shell (51) is fixedly connected to the upper side of the second body (21). The second motor (52) is installed inside the protective shell (51). Two sets of pulleys are installed inside the protective shell (51). The output end of the second motor (52) is connected to one set of the pulleys. A drive shaft (54) is fixedly connected to the lower side of another set of pulleys. A fan blade (55) is fixedly connected to the lower side of the drive shaft (54). The two sets of pulleys are connected by a belt (53). Two layers are provided inside the heating chamber (56). The fan blade (55) is located in the upper layer. A support frame (57) is fixedly connected to the inner side of the lower layer. Multiple heating tubes (58) are fixedly connected to the upper side of the support frame (57). A fixed plate is fixedly connected to the upper side of the heating chamber (56). The drive shaft (54) is rotatably connected to the fixed plate. The second motor (52) is fixedly connected to the fixed plate. Evenly distributed through holes are opened on the lower side of the layer where the fan blade (55) is located.

7. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 6, characterized in that: The second steam assembly (6) includes a second steam main pipe (61), a second steam nozzle (62), and a second steam branch pipe (63). The second steam main pipe (61) is located inside the heating chamber (56) and below the lower interlayer. The second steam main pipe (61) passes through one side of the heating chamber (56) and the furnace shell (22). The second steam main pipe (61) is connected to a uniformly distributed second steam branch pipe (63). The lower sides of the second steam main pipe (61) and the second steam branch pipe (63) are connected to a uniformly distributed second steam nozzle (62). The second steam branch pipe (63) and the second steam nozzle (62) are both located inside the heating chamber (56).

8. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 1, characterized in that: Closure assembly (7) is installed on the inlet side of the outer shell (12), the outlet side of the furnace shell (22), and the connection between the outer shell (12) and the furnace shell (22). The closure assembly (7) includes a mounting bracket (71), a cylinder (72), a closing plate (73), and a track plate (74). The cylinder (72) is fixedly connected to the inner side of the mounting bracket (71), the closing plate (73) is fixedly connected to the lower output end of the cylinder (72), and the track plate (74) is slidably connected to the outer side of the closing plate (73).

9. The surface oxidation treatment device for high airtight powder metallurgy products according to claim 6, characterized in that: A temperature and humidity sensor (8) is provided inside the heating chamber (56), and the temperature and humidity sensor (8) passes through one side of the heating chamber (56) and the furnace shell (22).

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