A method for manufacturing a check valve core

Abstract

This invention relates to the field of engineering component technology, specifically to a method for manufacturing a check valve core. The invention employs multi-process synergistic optimization, selecting raw materials containing 70-80% stainless steel powder and 10-15% alumina ceramic particles. A blank is prepared using powder metallurgy, and a cobalt-based alloy is clad onto the sealing surface using a 2000-2500W laser. After vacuum heat treatment at 1050℃ and cryogenic treatment at -196℃, the irregular flow channel is milled with a precision of ±0.01mm using five-axis CNC machining, combined with electrolytic polishing at 25-30℃ and potassium dichromate passivation treatment. Finally, the two blanks are sealed and welded, and the finished product is obtained after passing a 1.5MPa pressure holding test. This method gives the valve core high strength, high wear resistance, and corrosion resistance. The flow channel precision meets the requirements of high-pressure systems, and the surface finish and corrosion resistance are significantly improved. Testing shows that the wear life is more than three times that of traditional processes, effectively solving the problems of sealing failure and wear under complex operating conditions, and ensuring the reliability of the check valve.

Description

Technical Field

[0001] This invention relates to the field of engineering components technology, and specifically to a method for manufacturing a check valve core. Background Technology

[0002] A check valve, also known as a one-way valve, is a type of valve that automatically opens and closes by relying on the energy of the flowing medium itself. Its core function is to prevent the backflow of the medium in the pipeline, thereby protecting equipment such as pumps and compressors from damage caused by reverse flow and avoiding system pressure imbalance or medium backflow contamination. The working principle of existing check valves is based on the automatic action of the valve core. When the medium flows in the forward direction, the pressure pushes the valve disc to open, and the medium passes smoothly. If the medium flows in the reverse direction, the valve disc will close under its own weight, spring force, or reverse pressure, blocking the passage and achieving one-way flow. The performance of the check valve core directly affects the working reliability of the check valve.

[0003] However, existing valve core manufacturing methods have shortcomings. Ordinary materials and processing techniques are difficult to meet the requirements of high corrosion and high pressure environments. For complex flow channel structures, traditional processing methods are not precise enough, which can easily lead to high flow resistance and sealing failure. The surface treatment process is simple and has a short wear life.

[0004] Therefore, there is an urgent need for a manufacturing method that combines advanced materials and precision machining to improve the overall performance of valve cores. Summary of the Invention

[0005] This invention proposes a method for manufacturing a check valve core. Through multi-process synergistic optimization, this invention solves the problems of precision, corrosion resistance, and wear resistance of complex valve core structures.

[0006] The technical solution of the present invention is as follows: A method for manufacturing a check valve core, wherein the valve core blank is prepared by powder metallurgy, and the raw materials comprise by weight percentage: stainless steel powder: 70-80%, ceramic particles: 10-15%, and binder: 5-8%; the manufacturing method specifically includes the following steps:

[0007] Step (1): Laser cladding is performed on the billet, and cobalt-based alloy powder is clad in the sealing surface area of ​​the billet. The laser power is 2000-2500W and the scanning speed is 5-8mm / s.

[0008] Step (2): The clad blank is subjected to vacuum heat treatment. First, the temperature is raised to 1050℃ and held for 1 hour, then cooled to 600℃ at a rate of 30℃ / h, and then air cooled.

[0009] Step (3): Five-axis precision CNC machining is used to perform fine milling according to the special flow channel structure of the blank. The machining accuracy is controlled within ±0.01mm. The specific processing is as follows:

[0010] ①: First, a precise three-dimensional model of the embryo is obtained through three-dimensional scanning technology. Then, using CAD and CAM software, CNC machining path planning is performed to generate a refined CNC machining program, taking into account the irregular flow channels and complex three-dimensional structural features of the embryo.

[0011] ②: Securely clamp the blank onto the worktable of the five-axis CNC machining equipment, and perform tool calibration and positioning using a high-precision tool setter;

[0012] ③: During the machining process, carbide ball end mills are selected. According to the size and precision requirements of different parts of the flow channel, a layer milling process is adopted. The cutting depth is controlled at 0.1-0.3mm, the spindle speed is set at 8000-12000r / min, and the feed rate is 1000-1500mm / min.

[0013] ④: At the same time, the online measurement system integrated into the equipment is used to monitor the machining dimensions in real time, and the tool path is dynamically compensated and adjusted through the feedback control system to ensure that the machining accuracy is strictly controlled within the range of 0.01 mm.

[0014] ⑤: A high-pressure internal cooling cutting fluid system is used during the machining process, with a coolant pressure of 3-5 MPa;

[0015] Step (4): Perform surface electrolytic polishing on the processed blank. The specific treatment is as follows:

[0016] First polishing process: First, prepare a special electrolyte solution and strictly control the temperature of the electrolyte solution at 25-30℃. Maintain the temperature stability through a constant temperature device.

[0017] The second polishing process: The processed blank is firmly clamped with a corrosion-resistant hanger. The contact point between the hanger and the blank should avoid the key sealing surface and functional area. Then, the blank is slowly immersed in the electrolyte, the DC power supply is turned on, and the current density is adjusted to 15-20A / dm². During the polishing process, the ions in the electrolyte undergo an electrochemical reaction, and the micro-protrusions on the surface of the blank are preferentially dissolved.

[0018] The third polishing process: The electrolyte is stirred by mechanical stirring or circulating pump to make the ions in the solution evenly distributed. The polishing time is controlled at 10-15 minutes, and the changes in the gloss of the body surface are observed in real time during the process.

[0019] The fourth polishing process: The blank is quickly removed from the electrolyte and cleaned in multiple stages with deionized water to completely remove residual electrolyte. Finally, it is dried by low-temperature hot air circulation to lay the foundation for subsequent passivation and other processes.

[0020] Step (5): The two blanks are laminated and sealed to obtain the initial valve core. The air tightness test is performed. The valve core is placed in a gas environment with a pressure of 1.5MPa and the pressure is maintained for 5 minutes. The leakage is tested to be no more than 0.5mL / min. If the test is qualified, the finished check valve core is obtained.

[0021] The technical solution further defined in this invention is:

[0022] Furthermore, the stainless steel powder is 316L stainless steel, and the ceramic particles are alumina particles with a particle size of 5-10μm.

[0023] Furthermore, in step (1), the cobalt-based alloy powder contains 25-30% chromium, 5-8% tungsten, and the remainder is cobalt and trace impurities.

[0024] Furthermore, in step (2), after vacuum heat treatment, a deep cryogenic treatment is added, in which the embryo is placed in liquid nitrogen at -196℃ for 2 hours.

[0025] Furthermore, in step (4), after electrolytic polishing, passivation treatment is performed by soaking in potassium dichromate solution for 15-20 minutes.

[0026] The beneficial effects of this invention are as follows:

[0027] This invention combines stainless steel powder with ceramic particles using powder metallurgy, and then laser-clad cobalt-based alloy layers, giving the valve core high strength, high wear resistance, and excellent corrosion resistance.

[0028] For complex structures, 3D scanning modeling, five-axis CNC machining, and online measurement compensation technology are used to ensure that the machining accuracy of irregular flow channels is controlled within ±0.01mm, meeting the stringent requirements of high-pressure fluid systems for flow channel size and surface quality.

[0029] The combination of electropolishing and passivation treatment significantly improves the surface finish and corrosion resistance of the valve core, reduces media flow resistance, and lowers the risk of wear on the sealing surface.

[0030] By conducting airtightness testing, controlling material composition, and precisely adjusting parameters at each stage of the process, we ensure that the valve core products have stable quality and high reliability. Attached Figure Description

[0031] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0032] Figure 1 This is a schematic diagram of the special flow channel structure of the valve core of the present invention.

[0033] Among them: 1. embryo; 2. flow channel. Detailed Implementation

[0034] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] like Figure 1 As shown, this embodiment proposes a method for manufacturing a check valve core. The valve core blank is prepared using powder metallurgy, and the raw materials, by weight percentage, include: stainless steel powder: 70-80%, ceramic particles: 10-15%, and binder: 5-8%. The manufacturing method specifically includes the following steps:

[0037] Step (1): Laser cladding is performed on the billet, and cobalt-based alloy powder is clad in the sealing surface area of ​​the billet. The laser power is 2000-2500W and the scanning speed is 5-8mm / s.

[0038] Step (2): The clad blank is subjected to vacuum heat treatment. First, the temperature is raised to 1050℃ and held for 1 hour, then cooled to 600℃ at a rate of 30℃ / h, and then air cooled.

[0039] Step (3): Five-axis precision CNC machining is used to perform fine milling according to the special flow channel structure of the blank. The machining accuracy is controlled within ±0.01mm. The specific processing is as follows:

[0040] ①: First, a precise three-dimensional model of the embryo is obtained through three-dimensional scanning technology. Then, using CAD and CAM software, CNC machining path planning is performed to generate a refined CNC machining program, taking into account the irregular flow channels and complex three-dimensional structural features of the embryo.

[0041] ②: Securely clamp the blank onto the worktable of the five-axis CNC machining equipment, and perform tool calibration and positioning using a high-precision tool setter;

[0042] ③: During the machining process, carbide ball end mills are selected. According to the size and precision requirements of different parts of the flow channel, a layer milling process is adopted. The cutting depth is controlled at 0.1-0.3mm, the spindle speed is set at 8000-12000r / min, and the feed rate is 1000-1500mm / min.

[0043] ④: At the same time, the online measurement system integrated into the equipment is used to monitor the machining dimensions in real time, and the tool path is dynamically compensated and adjusted through the feedback control system to ensure that the machining accuracy is strictly controlled within the range of 0.01 mm.

[0044] ⑤: A high-pressure internal cooling cutting fluid system is used during the machining process, with a coolant pressure of 3-5 MPa;

[0045] Step (4): Perform surface electrolytic polishing on the processed blank. The specific treatment is as follows:

[0046] First polishing process: First, prepare a special electrolyte solution and strictly control the temperature of the electrolyte solution at 25-30℃. Maintain the temperature stability through a constant temperature device.

[0047] The second polishing process: The processed blank is firmly clamped with a corrosion-resistant hanger. The contact point between the hanger and the blank should avoid the key sealing surface and functional area. Then, the blank is slowly immersed in the electrolyte, the DC power supply is turned on, and the current density is adjusted to 15-20A / dm². During the polishing process, the ions in the electrolyte undergo an electrochemical reaction, and the micro-protrusions on the surface of the blank are preferentially dissolved.

[0048] The third polishing process: The electrolyte is stirred by mechanical stirring or circulating pump to make the ions in the solution evenly distributed. The polishing time is controlled at 10-15 minutes, and the changes in the gloss of the body surface are observed in real time during the process.

[0049] The fourth polishing process: The blank is quickly removed from the electrolyte and cleaned in multiple stages with deionized water to completely remove residual electrolyte. Finally, it is dried by low-temperature hot air circulation to lay the foundation for subsequent passivation and other processes.

[0050] Step (5): The two blanks are laminated and sealed to obtain the initial valve core. The air tightness test is performed. The valve core is placed in a gas environment with a pressure of 1.5MPa and the pressure is maintained for 5 minutes. The leakage is tested to be no more than 0.5mL / min. If the test is qualified, the finished check valve core is obtained.

[0051] The stainless steel powder is 316L stainless steel, and the ceramic particles are alumina particles with a particle size of 5-10μm.

[0052] In step (1), the cobalt-based alloy powder contains 25-30% chromium, 5-8% tungsten, and the remainder is cobalt and trace impurities.

[0053] In step (2), after vacuum heat treatment, a deep cryogenic treatment is added, in which the embryo is placed in liquid nitrogen at -196℃ for 2 hours.

[0054] In step (4), after electrolytic polishing, passivation treatment is performed by soaking in potassium dichromate solution for 15-20 minutes.

[0055] In this embodiment, step (1): laser cladding sealing surface strengthening, the purpose of which is to clad a cobalt-based alloy layer on the sealing surface area of ​​the blank, i.e. the annular surface where the valve core and the valve seat contact, to improve the high temperature wear resistance.

[0056] Process parameters: Cobalt-based alloy powder composition: 25-30% chromium, 5-8% tungsten, with the balance being cobalt and trace impurities; Laser power: 2000-2500W, scanning speed 5-8mm / s, spot diameter 1-2mm; Cladding layer thickness: 0.3-0.5mm, surface roughness Ra≤1.6μm.

[0057] Step (2): Vacuum heat treatment and deep cryogenic treatment. Vacuum heat treatment: heat up to 1050℃ and hold for 1 hour to eliminate residual stress in the cladding layer; slowly cool to 600℃ at 30℃ / h to avoid grain coarsening; air cool to room temperature to obtain a uniform structure.

[0058] Cryogenic treatment (optional): Immerse the billet in liquid nitrogen at -196°C for 2 hours to further refine the grains and improve the toughness of the material.

[0059] Step (3): Five-axis precision CNC machining, machining objective: to achieve ±0.01mm precision control for irregular flow channels and complex structures.

[0060] Key sub-steps:

[0061] ① 3D modeling and path planning: Obtain the billet model through 3D scanning and generate CNC programs using CAD / CAM software;

[0062] ② Tool calibration: Use a high-precision tool setter to ensure that the tool positioning error is ≤0.005mm;

[0063] ③ Layered milling: Carbide ball end mills are used, with a cutting depth of 0.1-0.3mm, a spindle speed of 8000-12000r / min, and a feed rate of 1000-1500mm / min;

[0064] ④ Online measurement and dynamic compensation: Adjust the tool path by monitoring data in real time to ensure machining accuracy;

[0065] ⑤ High-pressure internal cooling cutting fluid: The coolant pressure is 3-5MPa, which effectively reduces the cutting temperature and removes chips.

[0066] Step (4): Electrolytic polishing and passivation treatment. Electrolytic polishing: Electrolyte formulation: 60% phosphoric acid, 30% sulfuric acid, 10% deionized water, temperature 25-30℃; current density: 15-20A / dm², polishing time 10-15 minutes, surface roughness Ra≤0.2μm; Cleaning and drying: after multi-stage deionized water rinsing, low-temperature hot air circulation drying.

[0067] Passivation treatment (optional): Immerse in 5% potassium dichromate solution for 15-20 minutes to form a dense oxide film and enhance corrosion resistance.

[0068] Step (5): Sealing welding and airtightness test. Welding process: Vacuum electron beam welding is used to ensure that the weld is free of pores and cracks. Test standard: The valve core is placed in a 1.5MPa air pressure environment and pressure is maintained for 5 minutes. The leakage is ≤0.5mL / min. Micro-leakage is detected by helium mass spectrometry.

[0069] This demonstrates the following technical benefits: wear and corrosion resistance, with a cobalt-based cladding layer and ceramic particles reinforcing the blank, increasing lifespan by more than 3 times; high-precision flow channels, with five-axis machining ensuring the dimensional accuracy of complex flow channels and reducing media flow resistance; zero surface defects, with electrolytic polishing and passivation working together to eliminate micro-cracks and burrs; and high production efficiency, with the integration of laser cladding and CNC machining reducing subsequent grinding processes.

Claims

1. A method for manufacturing a check valve core, characterized in that, Valve core blanks are prepared using powder metallurgy, with raw materials comprising, by weight percentage: stainless steel powder: 70-80%, ceramic particles: 10-15%, and binder: 5-8%. The manufacturing method specifically includes the following steps: Step (1): Laser cladding is performed on the billet, and cobalt-based alloy powder is clad in the sealing surface area of ​​the billet. The laser power is 2000-2500W and the scanning speed is 5-8mm / s. Step (2): The clad blank is subjected to vacuum heat treatment. First, the temperature is raised to 1050℃ and held for 1 hour, then cooled to 600℃ at a rate of 30℃ / h, and then air cooled. Step (3): Five-axis precision CNC machining is used to perform fine milling according to the flow channel structure of the blank, and the machining accuracy is controlled within ±0.01mm; Step (4): Perform surface electrolytic polishing on the processed blank; Step (5): The two blanks are laminated and sealed to obtain the initial valve core. The air tightness test is performed. The valve core is placed in a gas environment with a pressure of 1.5MPa and the pressure is maintained for 5 minutes. The leakage is tested to be no more than 0.5mL / min. If the test is qualified, the finished check valve core is obtained. The specific processing in step (4) is as follows: First polishing process: First, prepare a special electrolyte solution and strictly control the temperature of the electrolyte solution at 25-30℃. Maintain the temperature stability through a constant temperature device. The second polishing process: The processed blank is firmly clamped with a corrosion-resistant hanger. The contact point between the hanger and the blank should avoid the key sealing surface and functional area. Then, the blank is slowly immersed in the electrolyte, the DC power supply is turned on, and the current density is adjusted to 15-20A / dm². During the polishing process, the ions in the electrolyte undergo an electrochemical reaction, and the micro-protrusions on the surface of the blank are preferentially dissolved. The third polishing process involves using a circulating pump to agitate the electrolyte, ensuring uniform ion distribution in the solution. The polishing time is controlled at 10-15 minutes, during which the changes in the gloss of the substrate surface are observed in real time. The fourth polishing process: The blank is quickly removed from the electrolyte and cleaned in multiple stages with deionized water to completely remove residual electrolyte. Finally, it is dried by low-temperature hot air circulation to lay the foundation for subsequent passivation treatment. The stainless steel powder is 316L stainless steel, the ceramic particles are alumina particles with a particle size of 5-10μm, the cobalt-based alloy powder in step (1) contains 25-30% chromium and 5-8% tungsten, the remainder is cobalt and trace impurities, the vacuum heat treatment in step (2) is followed by deep cryogenic treatment, the blank is placed in liquid nitrogen at -196℃ for 2 hours, the electrolytic polishing in step (4) is followed by passivation treatment, and potassium dichromate solution is used for soaking for 15-20 minutes.

2. The method for manufacturing a check valve core according to claim 1, characterized in that, The specific processing in step (3) is as follows: ①: First, a precise three-dimensional model of the embryo is obtained through three-dimensional scanning technology. Then, using CAD and CAM software, CNC machining path planning is performed to generate a refined CNC machining program, taking into account the irregular flow channels and complex three-dimensional structural features of the embryo. ②: Securely clamp the blank onto the worktable of the five-axis CNC machining equipment, and perform tool calibration and positioning using a high-precision tool setter; ③: During the machining process, carbide ball end mills are selected. According to the size and precision requirements of different parts of the flow channel, a layer milling process is adopted. The cutting depth is controlled at 0.1-0.3mm, the spindle speed is set at 8000-12000r / min, and the feed rate is 1000-1500mm / min. ④: At the same time, the online measurement system integrated into the equipment is used to monitor the machining dimensions in real time, and the tool path is dynamically compensated and adjusted through the feedback control system to ensure that the machining accuracy is strictly controlled within ±0.01mm. ⑤: A high-pressure internal cooling cutting fluid system is used during the machining process, with a coolant pressure of 3-5 MPa.

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