Anti-cracking high-strength forming process of charging pile circuit board nut column

Abstract

The invention discloses an anti-cracking high-strength forming process for a nut column of a charging pile circuit board, and relates to the field of metal material modification processing, and the anti-cracking high-strength forming process comprises the following steps: S1, material preparation: selecting a modified SWRCH22A alloy material, and carrying out trademark, packaging, batch number, chemical composition and RoHS conformity inspection on the modified SWRCH22A alloy material until the modified SWRCH22A alloy material is qualified; s2, cold heading forming is conducted, specifically, after the modified SWRCH22A alloy material is preheated, a nut column blank is formed through a numerical control cold heading machine; s3, thread rolling machining is conducted, specifically, thread rolling treatment is conducted on the blank, burrs are removed in the machining process, and it is guaranteed that the thread size meets the design requirement; and S4, segmented heat treatment is conducted, specifically, quenching treatment and tempering treatment are conducted in sequence, so that the workpiece meets the preset hardness requirement. Through targeted optimization of the material formula and the whole-flow process design, the problems of insufficient material cracking resistance, poor processing precision, poor performance stability, insufficient corrosion resistance, low product percent of pass and the like in an existing charging pile circuit board nut column forming process are effectively solved.

Description

Technical Field

[0001] This invention relates to the field of metal material modification and processing, specifically to a high-strength, crack-resistant forming process for the nut column of a charging pile circuit board. Background Technology

[0002] With the rapid development of the new energy vehicle industry, the demand for charging piles, as a core supporting infrastructure, continues to surge. Their operational stability and lifespan directly affect user experience and travel safety. The charging pile circuit board, as the core control unit, undertakes critical functions such as power distribution and signal transmission. The nut column, as the core connector for fixing the circuit board, must withstand long-term installation and fastening stress, environmental temperature and humidity changes, and minor vibrations. Therefore, stringent requirements are placed on its strength, crack resistance, corrosion resistance, and dimensional accuracy. Its product quality directly affects the overall reliability and safety of the charging pile.

[0003] Currently, the industry's forming process for the nut pillars of charging pile circuit boards mostly adopts conventional metal processing solutions. These typically use ordinary carbon steel or standard SWRCH series alloy materials, and production is completed after cold heading, simple thread rolling, a single heat treatment, and basic electroplating. The specific process is roughly as follows: after the material passes inspection, it is directly cold-headed to form a blank; subsequently, threads are processed using ordinary thread rolling equipment; then, a one-time heat treatment is performed to adjust the hardness; finally, conventional electroplating methods such as galvanizing are used for surface anti-corrosion treatment; and the finished product is packaged and stored after simple dimensional and visual inspections.

[0004] However, existing molding processes have many shortcomings, making it difficult to meet the high-performance requirements of charging pile circuit board nut pillars: First, the material selection lacks targeted optimization; the yield strength and tensile strength of ordinary alloy materials are too low, and the crack resistance has not been improved through element modification, resulting in stress cracking of the nut pillars during installation, fastening, or long-term use; Second, the processing parameters are not precise enough; proper preheating treatment is not performed before cold heading; improper mold material and surface treatment methods can easily cause deviations in blank dimensions or surface damage; unreasonable selection of lubricant and parameter control during thread rolling can easily lead to burrs on the thread root diameter, affecting assembly accuracy; Third... The heat treatment process design is imperfect, and the segmented quenching-tempering process is not adopted, resulting in uneven hardness between the surface and core of the workpiece, making it impossible to balance strength and toughness. At the same time, the surface treatment only uses simple electroplating, lacking effective pretreatment and hydrogen removal processes, resulting in poor coating adhesion, insufficient corrosion resistance, short pass time in neutral salt spray test, and easy coating peeling. Fourth, there is a lack of a systematic online process inspection mechanism in the production process, which makes it easy for defective products to be transferred during mass production. Moreover, the finished product packaging is simple, and the product is easily deformed or the coating is damaged due to bumps and squeezing during transportation, which ultimately affects the installation stability of the charging pile circuit board and may even cause safety hazards. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a high-strength, crack-resistant molding process for the nut column of a charging pile circuit board, so as to solve the technical problems of insufficient crack resistance and strength, poor processing accuracy and corrosion resistance, and substandard testing and use stability of the nut column of the charging pile circuit board prepared by traditional processes.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high-strength, crack-resistant forming process for a charging pile circuit board nut column, comprising the following core steps: S1, Material preparation: Selecting modified SWRCH22A alloy material, which passes the grade, packaging, batch number, chemical composition, and RoHS compliance inspection; S2, Cold heading: After preheating the modified SWRCH22A alloy material, forming the nut column blank using a CNC cold heading machine; S3, Thread rolling: Performing thread rolling on the blank, removing burrs during the process and ensuring that the thread dimensions meet the design requirements; S4, Segmented heat treatment: Performing quenching and tempering treatments sequentially to achieve the preset hardness requirements; S5, Surface treatment: Performing surface pretreatment, zinc-nickel alloy electroplating, and hydrogen removal treatment sequentially; S6, Finished product inspection: Inspecting the dimensions, appearance, hardness, and breaking torque of the electroplated workpiece, and after passing the inspection, packaging, warehousing, and shipping inspections.

[0007] The present invention is further configured such that the chemical composition of the modified SWRCH22A alloy material in step S1, by mass fraction, is: C 0.18-0.23%, Si 0.15-0.35%, Mn 0.70-1.00%, P≤0.030%, S≤0.030%, and Cr 0.05-0.10% and Mo 0.02-0.05% are added, with a yield strength ≥350MPa and a tensile strength ≥500MPa.

[0008] The present invention is further configured such that, in step S2, the preheating temperature is 200-250℃ and the preheating time is 30-60min; the cold heading pressure is 800-1000MPa and the cold heading speed is 5-10 times / min; the cold heading machine mold is made of Cr12MoV material and the mold surface is nitrided with a nitriding layer thickness of 0.05-0.10mm.

[0009] The present invention is further configured such that, in step S3, the thread rolling process is carried out using a CNC thread rolling machine, and a graphite-based lubricant is applied to the blank before thread rolling, with a lubricant thickness of 0.02-0.05 mm; the thread rolling speed is 15-25 m / min, the thread rolling pressure is 300-500 MPa, and the thread root diameter is smooth and burr-free.

[0010] The present invention is further configured such that, in step S4: the quenching treatment is performed by holding at 850-900℃ for 60-90 minutes and then oil cooling to room temperature, with the quenching oil temperature being 60-80℃; the tempering treatment is performed by holding at 400-450℃ for 120-180 minutes and then air cooling to room temperature; after treatment, the surface hardness of the workpiece is 450-550HV0.3, and the core hardness is 280-340HV5.

[0011] The present invention is further configured such that, in step S5: the surface pretreatment includes ultrasonic cleaning at 40-60 kHz for 10-15 min, pickling and degreasing with 5-10% hydrochloric acid solution at 20-30℃ for 5-10 min, and phosphating to form a 1-3 μm phosphating film; the electroplating process has a current density of 1-3 A / dm², an electroplating time of 20-40 min, a coating thickness of 8-13 μm, and a nickel mass fraction of 10-15% in the zinc-nickel alloy coating; the hydrogen removal treatment is held at 80-100℃ for 30-60 min, and a neutral salt spray test ≥8H.

[0012] The present invention is further configured such that, in step S6: the size inspection adopts a CCD vision inspection device with an inspection accuracy of ±0.001mm and a size deviation of ≤±0.05mm; the appearance inspection adopts machine vision + manual re-inspection, with no cracks, no deformation, and no coating peeling; the breaking torque is ≥0.65N・m.

[0013] The present invention is further configured such that steps S2 to S5 include online process inspection, where one piece is randomly selected from every 500 pieces processed for size and appearance inspection, and if any defective product is found, the machine is immediately stopped and the process parameters are adjusted.

[0014] The present invention is further configured such that, in step S6, the packaging adopts carrier tape packaging with a carrier tape width of 24mm and a blister pack height of ≤18mm, and bumps and squeezing are avoided during packaging and transportation.

[0015] In summary, the present invention has the following main beneficial effects: This invention effectively solves the problems of insufficient material crack resistance, poor processing accuracy, poor performance stability, insufficient corrosion resistance, and low product qualification rate in the existing charging pile circuit board nut column forming process by specifically optimizing the material formula and the whole process design: The use of modified SWRCH22A alloy material with added Cr and Mo significantly improves the yield strength and tensile strength of the material, enhancing the crack resistance of the nut column from the source; precise preheating treatment before cold heading, the application of Cr12MoV nitriding mold, and the optimization of CNC cold heading parameters ensure the dimensional accuracy and surface quality of the blank, avoiding damage during the forming process; the use of a CNC thread rolling machine with graphite-based lubricant achieves a smooth, burr-free thread bottom diameter, improving assembly compatibility; segmented quenching-returning... The heat treatment process ensures that the surface and core hardness of the workpiece reach the preset range and are evenly distributed, balancing strength and toughness. The surface treatment process, including ultrasonic cleaning, pickling and degreasing, phosphating, zinc-nickel alloy electroplating, and hydrogen removal, significantly improves coating adhesion and corrosion resistance, achieving a neutral salt spray test pass time of ≥8 hours. An online process inspection combined with CCD vision inspection and machine vision + manual re-inspection effectively intercepts defective products, ensuring product consistency. The carrier packaging method and protective requirements during transportation prevent deformation and coating damage during product handling, ultimately significantly improving the overall quality and reliability of the charging pile circuit board nuts, extending the service life of the core control unit, and ensuring the stability and safety of the charging pile operation. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0017] The following detailed description of the crack-resistant high-strength molding process for the nut column of the charging pile circuit board of the present invention is provided with reference to specific embodiments. The embodiments listed are only for explaining the present invention and are not intended to limit the scope of protection of the present invention.

[0018] Example 1

[0019] like Figure 1 As shown in the figure, this embodiment provides a high-strength, crack-resistant molding process for the nut post of a charging pile circuit board. The specific steps are as follows: S1. Material Preparation Modified SWRCH22A alloy material was selected, and a full inspection was conducted after procurement: the material grade was verified as modified SWRCH22A, the packaging was intact and undamaged, the batch number was 20240601, and the chemical composition by mass fraction was as follows: C 0.20%, Si 0.25%, Mn 0.85%, P 0.025%, S 0.022%, Cr 0.08%, Mo 0.035%, with the content of each element within the specified range (C 0.18-0.23%, Si 0.15-0.35%, Mn 0.70-1.00%, P≤0.030%, S≤0.030%, Cr 0.05-0.10%, Mo 0.02-0.05%); the content of harmful substances such as lead, mercury, and cadmium was tested by a RoHS tester and met the requirements of the RoHS 2.0 directive. The tensile test showed that the material has a yield strength of 380 MPa and a tensile strength of 530 MPa, which meets the requirements of "yield strength ≥ 350 MPa and tensile strength ≥ 500 MPa".

[0020] S2, Cold heading First, the qualified modified SWRCH22A alloy material is preheated: the preheating temperature is set at 220℃ (limited to 200-250℃), the preheating time is 45 min (limited to 30-60 min), and the preheating equipment is an electrically heated constant temperature furnace, with temperature fluctuation controlled within ±5℃. After preheating, the material is fed into a CNC cold heading machine (model: Z12-40) for billet forming. The cold heading pressure is set at 900MPa (limited to 800-1000MPa), and the cold heading speed is 8 times / min (limited to 5-10 times / min). The cold heading machine mold is made of Cr12MoV material, and the mold surface is gas nitrided. The nitrided layer thickness is measured to be 0.08mm (limited to 0.05-0.10mm), and the surface roughness Ra of the mold working surface is ≤0.8μm. The formed nut column billet is cylindrical, with an outer diameter of 5mm and a length of 20mm, with no surface damage and no dimensional deviation.

[0021] S3, thread rolling process The cold-headed billet was threaded using a CNC thread rolling machine (model: 3T-600). Before thread rolling, a graphite-based lubricant was evenly applied to the surface of the billet using an automatic spraying device. The lubricant thickness was controlled to be 0.03mm (limited to 0.02-0.05mm), and the lubricant purity was ≥99.5%, free of impurities. The thread rolling process parameters were set as follows: thread rolling speed 20m / min (limited to 15-25m / min), thread rolling pressure 400MPa (limited to 300-500MPa), and thread rolling wheel speed matched to 1200r / min. During processing, burrs generated during thread processing were removed in real time using an online burr removal device. The final thread specification was M3×0.5, with a smooth thread root diameter. Microscopic observation revealed no burrs or thread deformation, and the thread dimensions met the requirements of GB / T196-2003 standard.

[0022] S4, Segmented Heat Treatment The workpiece after thread rolling is sent to a continuous heat treatment furnace for segmented processing, specifically divided into two processes: quenching and tempering. Quenching treatment: The quenching temperature is set to 880℃ (limited to 850-900℃), the holding time is 75min (limited to 60-90min), and after the holding time is completed, the workpiece is quickly immersed in quenching oil to cool to room temperature. The quenching oil temperature is controlled at 70℃ (limited to 60-80℃), the quenching oil type is L-QC320, and the cooling rate is ≥15℃ / s.

[0023] Tempering treatment: After quenching, the workpiece is transferred to a tempering furnace. The tempering temperature is set to 420℃ (limited to 400-450℃), and the holding time is 150min (limited to 120-180min). After the holding time is completed, the workpiece is cooled to room temperature by air cooling. During the cooling process, the workpieces are avoided from stacking to ensure uniform cooling.

[0024] After heat treatment, the hardness of the workpiece was tested using a Vickers hardness tester (model: HV-1000): the surface hardness was 500HV0.3 and the core hardness was 310HV5, both of which fell within the specified range (surface hardness 450-550HV0.3, core hardness 280-340HV5).

[0025] S5, Surface Treatment The surface treatment process involves surface pretreatment, zinc-nickel alloy electroplating, and hydrogen removal treatment, as follows: Surface pretreatment: Ultrasonic cleaning: A 40kHz ultrasonic cleaner (model: KQ-600VDE) is used, with a cleaning time of 12 minutes (limited to 10-15 minutes). The cleaning solution is a neutral cleaning agent (concentration 5%), and the cleaning temperature is 25℃. This removes oil and metal debris from the surface of the workpiece.

[0026] Pickling and degreasing: Immerse the cleaned workpiece in an 8% hydrochloric acid solution at 25℃ (limited to 20-30℃, 5-10% hydrochloric acid solution) for 8 minutes (limited to 5-10 minutes), and then rinse with deionized water 3 times, 2 minutes each time.

[0027] Phosphating treatment: Place the workpiece in a phosphating bath at a temperature of 40°C for 10 minutes to form a phosphating film with a thickness of 2μm (limited to 1-3μm). The adhesion grade of the phosphating film is ≥1 (GB / T9286-1998).

[0028] Zinc-nickel alloy electroplating: A rack plating method was used, with an alkaline zinc-nickel alloy plating solution. The current density was set to 2 A / dm² (limited to 1-3 A / dm²), the plating time to 30 min (limited to 20-40 min), and the plating temperature to 25℃. After plating, the coating thickness was measured to be 10 μm (limited to 8-13 μm). X-ray fluorescence spectroscopy analysis showed that the nickel mass fraction in the zinc-nickel alloy coating was 12% (limited to 10-15%).

[0029] Hydrogen removal treatment: The electroplated workpiece is placed in a constant temperature oven with a temperature set at 90℃ (limited to 80-100℃) and a holding time of 45 minutes (limited to 30-60 minutes) to remove hydrogen atoms that have penetrated into the workpiece during the electroplating process and prevent hydrogen embrittlement cracking.

[0030] S6. Finished Product Inspection The workpiece after hydrogen removal undergoes comprehensive testing. The testing items and methods are as follows: Dimensional inspection: A CCD vision inspection device (model: MV-2000) was used with an inspection accuracy of ±0.001mm. The inspection items included key dimensions such as outer diameter, length, and thread root diameter. The inspection results showed that the dimensional deviation was ±0.03mm, which meets the requirement of "dimensional deviation ≤ ±0.05mm".

[0031] Appearance inspection: A machine vision inspection system (inspection speed 300 pieces / min) is used for preliminary inspection. Then, the workpieces that have been screened by the machine are manually re-inspected 100%. The inspection standards are: no cracks, no deformation, no coating peeling, and no scratches. In this embodiment, the appearance pass rate is 100%.

[0032] Hardness testing: Ten workpieces were randomly selected and their surface and core hardness were tested using a Vickers hardness tester. The average test results were 495 HV0.3 for surface hardness and 305 HV5 for core hardness, both of which met the requirements.

[0033] Destructive torque test: The destructive torque was tested using a torque tester (model: ANL-20). The test method was as follows: the nut post was fixed and an axial torque was applied through a torque wrench until the thread broke. The test results showed that the average destructive torque was 0.72 N·m, which meets the requirement of "destructive torque ≥ 0.65 N·m".

[0034] Corrosion resistance test: Five workpieces were randomly selected for a neutral salt spray test (GB / T10125-2021). The test temperature was 35℃, the salt solution concentration was 5%, and the test time was 8 hours. After the test, there was no rust or coating peeling on the workpiece surface, which met the requirement of "neutral salt spray test ≥8H".

[0035] Online process inspection During the production process from steps S2 to S5, online process inspection points are set up: one piece is randomly selected from every 500 pieces processed for dimensional and appearance inspection. The inspection items include the outer diameter and length of the cold-headed blank, the thread size after thread rolling, the hardness after heat treatment, and the coating thickness after electroplating. In this embodiment, a total of 10,000 workpieces were processed, and 20 inspections were conducted. No defective products were found, and the process parameters remained stable.

[0036] Packaging, warehousing and outgoing inspection Qualified workpieces are packaged using carrier tape with a tape width of 24mm and a blister pack height of 16mm (≤18mm). Each reel contains 1000 pieces. Automated packaging machines are used to avoid damage to the plating caused by manual handling. After packaging, labels are affixed to the carrier tape, including part number, batch number, quantity, production date, and inspection certificate. Upon warehousing, the cleanliness of the packaging, the clarity of the labels, and the accuracy of the quantity are checked. The storage environment is dry and well-ventilated, with a temperature of 15-25℃ and relative humidity ≤60%. Before shipment, the shipping report, quantity, labels, and key dimensions are checked again to ensure compliance with customer requirements. Shockproof packaging is used during transportation to avoid bumps and compression.

[0037] Example 2

[0038] This embodiment is a limited boundary parameter embodiment, and the specific process parameters are as follows: S1 material composition: C 0.18%, Si 0.15%, Mn 0.70%, P 0.030%, S 0.030%, Cr 0.05%, Mo 0.02%, yield strength 355MPa, tensile strength 505MPa; S2 preheating temperature 200℃, time 30min, cold heading pressure 800MPa, speed 5 times / min, mold nitriding layer thickness 0.05mm; S3 lubricant thickness 0.02mm, thread rolling speed 15m / min, pressure 300MPa; S4 quenching temperature 850℃, holding temperature 60min, quenching oil temperature 60℃; tempering temperature 400℃, holding temperature 120min, after treatment surface hardness 455HV0.3, core hardness 285HV5. S5 ultrasonic cleaning frequency 60kHz, time 10min; pickling and degreasing temperature 20℃, hydrochloric acid concentration 5%, time 5min; phosphating film thickness 1μm; electroplating current density 1A / dm², time 20min, coating thickness 8μm, nickel mass fraction 10%; dehydrogenation temperature 80℃, time 30min. The S6 has a dimensional deviation of ±0.04mm, a breaking torque of 0.66N・m, and shows no abnormalities after 8 hours of neutral salt spray testing.

[0039] The remaining steps are the same as in Example 1. The workpiece processed in this example was tested and all performance indicators met the defined range, proving that the process parameter range of the present invention has good stability and reliability.

[0040] Comparative Example The conventional nut post forming process for charging pile circuit boards is adopted in existing technology, with the following specific parameters: Material: Standard SWRCH22A alloy material, chemical composition (mass fraction): C 0.20%, Si 0.20%, Mn 0.80%, P 0.028%, S 0.025%, no Cr or Mo added, yield strength 280MPa, tensile strength 420MPa; Cold heading: No preheating treatment, cold heading pressure 700MPa, speed 12 times / min, mold material is Cr12, no nitriding treatment; Thread rolling: Machine oil is used as a lubricant, thread rolling speed is 30m / min, and pressure is 250MPa; Heat treatment: single tempering treatment, temperature 350℃, holding for 90min, surface hardness 380HV0.3, core hardness 250HV5; Surface treatment: Zinc plating only, no pretreatment or hydrogen removal, coating thickness 6μm, neutral salt spray test 3H; Inspection: Dimensions are measured using vernier calipers with an accuracy of ±0.01mm, and visual inspection is performed manually with a destructive torque of 0.55N・m. Packaging: Packaged in plastic bags, with no special protection.

[0041] Performance comparison data table Table 1 Comparison of Material Properties

[0042] Table 2 Comparison of Process Parameters

[0043] Technical Effect Description As can be seen from the above embodiments and comparative data, the high-strength molding process for crack-resistant nut columns of the charging pile circuit board of the present invention has the following significant technical effects: In terms of materials: By adding Cr (0.05-0.10%) and Mo (0.02-0.05%) to the SWRCH22A alloy, the yield strength and tensile strength of the material are significantly improved, enhancing the crack resistance of the nut post from the source. Compared with the existing technology, the yield strength is increased by 26.8%-28.9%, the tensile strength is increased by 20.2%-26.2%, and there is no cracking after 1000 installations, while the cracking rate of the existing technology reaches 8.5%.

[0044] In terms of machining accuracy: precise preheating before cold heading, application of Cr12MoV nitriding mold and optimization of CNC cold heading parameters, combined with CCD visual inspection (accuracy ±0.001mm), enable dimensional deviation to be controlled within ±0.05mm, which is far superior to the ±0.08mm of the existing technology. The thread root diameter is smooth and burr-free, and the assembly compatibility is greatly improved.

[0045] In terms of performance stability: the segmented quenching-tempering process makes the surface and core of the workpiece have uniform hardness within the preset range, taking into account both strength and toughness. Compared with existing technologies, the surface hardness is increased by 19.7%-25.0%, the core hardness is increased by 14.0%-22.0%, and the breaking torque is increased by 20.0%-30.9%.

[0046] In terms of corrosion resistance: The complete surface treatment process (ultrasonic cleaning → pickling and degreasing → phosphating → zinc-nickel alloy electroplating → hydrogen removal) enables the neutral salt spray test to meet the standard time of ≥8H, compared with the existing technology of 3H, the corrosion resistance is improved by more than 166.7%, effectively avoiding coating peeling and rust.

[0047] Regarding product qualification rate: The combination of online process inspection and finished product full-item inspection enables the product qualification rate to reach over 99.5%, which is more than 7.8% higher than the existing technology's 92.3%, significantly reducing production costs.

[0048] Regarding packaging and transportation: the carrier belt packaging method and the shockproof requirements during transportation prevent product deformation and coating damage, ensuring the quality stability of the product during circulation.

[0049] In summary, this invention, through targeted optimization of material formulation and whole-process design, comprehensively solves the problems existing in the prior art, such as insufficient material crack resistance, poor processing accuracy, poor performance stability, insufficient corrosion resistance, and low product qualification rate. It significantly improves the overall quality and reliability of the charging pile circuit board nut column, extends the service life of the charging pile core control unit, and ensures the stability and safety of the charging pile operation.

[0050] The steps of the methods or algorithms described in this application can be directly embedded in hardware, software units executed by a processor, or a combination of both. Exemplarily, a storage medium can be connected to a processor so that the processor can read information from and write information to the storage medium. Optionally, the storage medium can also be integrated into the processor. Optionally, the processor and the storage medium can also be located in different components within a terminal. These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable apparatus for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0051] Although this application has been described in conjunction with specific features and embodiments, it is obvious that various modifications and combinations can be made thereto without departing from the spirit and scope of this application. Accordingly, this specification and drawings are merely illustrative examples of this application and are considered to cover any and all modifications, variations, combinations, or equivalents within the scope of this application. Clearly, those skilled in the art can make various alterations and modifications to this application without departing from its scope. Thus, if such modifications and modifications fall within the scope of this application and its equivalents, this application intends to include such modifications and modifications.

Claims

1. A high-strength, crack-resistant molding process for the nut post of a charging pile circuit board, characterized in that, Includes the following steps: S1. Material preparation: Modified SWRCH22A alloy material is selected and has passed the inspection for grade, packaging, batch number, chemical composition and RoHS compliance. S2. Cold heading: After preheating the modified SWRCH22A alloy material, the nut column blank is formed using a CNC cold heading machine; S3. Thread rolling: The blank is subjected to thread rolling, during which burrs are removed and the thread size is ensured to meet the design requirements. S4. Segmented heat treatment: Quenching and tempering are performed sequentially to make the workpiece reach the preset hardness requirements. S5. Surface treatment: Surface pretreatment, zinc-nickel alloy electroplating and hydrogen removal treatment are performed in sequence. S6. Finished Product Inspection: The dimensions, appearance, hardness, and breaking torque of the electroplated workpieces are inspected. After passing the inspection, the workpieces are packaged, put into storage, and shipped.

2. The high-strength, crack-resistant molding process for the nut post of the charging pile circuit board according to claim 1, characterized in that, The chemical composition of the modified SWRCH22A alloy material described in step S1, by mass fraction, is: C 0.18-0.23%, Si 0.15-0.35%, Mn 0.70-1.00%, P≤0.030%, S≤0.030%, with the addition of Cr 0.05-0.10% and Mo 0.02-0.05%, yield strength ≥350MPa, and tensile strength ≥500MPa.

3. The high-strength, crack-resistant molding process for the charging pile circuit board nut post according to claim 1, characterized in that, In step S2, the preheating temperature is 200-250℃ and the preheating time is 30-60min; the cold heading pressure is 800-1000MPa and the cold heading speed is 5-10 times / min; the cold heading machine mold is made of Cr12MoV material and the mold surface is nitrided with a nitriding layer thickness of 0.05-0.10mm.

4. The high-strength, crack-resistant molding process for the charging pile circuit board nut post according to claim 1, characterized in that, In step S3, the thread rolling process is carried out using a CNC thread rolling machine. Before thread rolling, a graphite-based lubricant is applied to the blank with a thickness of 0.02-0.05 mm. The thread rolling speed is 15-25 m / min, the thread rolling pressure is 300-500 MPa, and the thread root diameter is smooth without burrs.

5. The high-strength, crack-resistant molding process for the nut post of the charging pile circuit board according to claim 1, characterized in that, In step S4: the quenching treatment is to hold at 850-900℃ for 60-90 minutes and then oil cool to room temperature, with the quenching oil temperature being 60-80℃; the tempering treatment is to hold at 400-450℃ for 120-180 minutes and then air cool to room temperature; after treatment, the surface hardness of the workpiece is 450-550HV0.3, and the core hardness is 280-340HV5.

6. The high-strength, crack-resistant molding process for the nut post of the charging pile circuit board according to claim 1, characterized in that, In step S5: the surface pretreatment includes ultrasonic cleaning at 40-60 kHz for 10-15 min, pickling and degreasing with 5-10% hydrochloric acid solution at 20-30℃ for 5-10 min, and phosphating to form a 1-3 μm phosphating film; the electroplating process has a current density of 1-3 A / dm², an electroplating time of 20-40 min, a coating thickness of 8-13 μm, and a nickel mass fraction of 10-15% in the zinc-nickel alloy coating; the hydrogen removal treatment is a heat treatment at 80-100℃ for 30-60 min, and a neutral salt spray test for ≥8 hours.

7. The high-strength, crack-resistant molding process for the nut post of the charging pile circuit board according to claim 1, characterized in that, In step S6: Dimensional inspection uses CCD vision inspection equipment with an inspection accuracy of ±0.001mm and a dimensional deviation of ≤±0.05mm; Appearance inspection uses machine vision + manual re-inspection to ensure no cracks, no deformation, and no coating peeling; the destructive torque is ≥0.65N・m.

8. The high-strength, crack-resistant molding process for the nut post of the charging pile circuit board according to claim 1, characterized in that, Steps S2 to S5 involve setting up online process inspection. One piece is randomly selected from every 500 pieces processed for dimensional and appearance inspection. If any defective product is found, the machine is immediately stopped and the process parameters are adjusted.

9. The high-strength, crack-resistant molding process for the nut post of the charging pile circuit board according to claim 1, characterized in that, In step S6, the packaging uses carrier tape with a width of 24mm and a blister pack height of ≤18mm. Bumps and squeezing should be avoided during packaging and transportation.

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