Secondary anti-loosening method for residual deformation of press-fit terminal

Abstract

The invention discloses a secondary locking method for residual deformation of a press-fit terminal, and relates to the technical field of locking of press-fit terminals for electrical connection, and the method comprises the following steps: preparation of a composite energy storage terminal base material, a residual potential energy directional anchoring press-fit process, and environmental energy capture triple cycle locking trigger. According to the invention, by using a cooperative technology of four-layer composite structure base material preparation, a residual potential energy directional anchoring pressing process and environmental energy capture triple cycle locking triggering, the problems that residual deformation of a pressing terminal is released disorderly, temperature and humidity cycles are aggravated and loosened, and an existing anti-loosening scheme is high in cost and only passively relieves are solved; according to the utility model, resource utilization of residual deformation and environmental energy is realized, additional anti-loosening parts and secondary processing are not needed, a cyclic self-strengthening anti-loosening effect is achieved, the contact pressure is stabilized, and the service life of the terminal is remarkably prolonged.

Description

Technical Field

[0001] This invention relates to the field of anti-loosening technology for crimp terminals used in electrical connections, specifically a secondary anti-loosening method for residual deformation of crimp terminals. Background Technology

[0002] Press-fit terminals are widely used in automotive, industrial control, and electronic equipment fields due to their reliable connection, efficient assembly, and low cost. They form a tight connection between the terminal and the wire / substrate through a pressing process. During the pressing process, the terminal's metal substrate undergoes plastic deformation, inevitably resulting in residual deformation and some elastic residual stress. This residual deformation has long been considered a static defect in the field and is a potential hazard for loosening of the terminal after long-term use.

[0003] In practical applications, press-fit terminals often face cyclical changes in ambient temperature and humidity, such as the alternating high and low temperatures in automotive engine compartments and the diurnal temperature and humidity fluctuations in outdoor electronic devices. In existing technologies, temperature and humidity cycles exacerbate the relaxation effect of residual deformation: on the one hand, temperature changes cause differences in the coefficients of thermal expansion between the terminal and mating components such as wires and substrates, generating interaction forces and further releasing the elastic stress in the residual deformation; on the other hand, humidity changes may affect the mechanical properties of the terminal's metal substrate, reducing its deformation stability, ultimately leading to a decrease in contact pressure and an increase in the mating gap between the terminal and mating components, causing connection loosening. In severe cases, this can affect the reliability of electrical signal transmission or even lead to circuit failure.

[0004] To address the aforementioned loosening issue, existing anti-loosening solutions passively resist residual deformation or add additional locking structures. For example, during terminal assembly, additional components such as elastic washers and anti-loosening nuts are added to enhance contact pressure or increase frictional resistance; or secondary processing techniques such as secondary pressing and applying anti-loosening adhesive are used to compensate for residual deformation defects from the initial pressing. However, these solutions have significant limitations: additional anti-loosening components increase assembly complexity and material costs, while secondary processing extends the production cycle and increases manufacturing costs. Furthermore, these solutions do not utilize the correlation between residual deformation and temperature and humidity cycling conditions for optimization; they can only passively alleviate loosening and cannot fundamentally utilize the inherent characteristics of residual deformation to achieve a dynamically adaptable anti-loosening effect.

[0005] In view of this, a secondary anti-loosening method for residual deformation of press-fit terminals is provided to overcome the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide a secondary anti-loosening method for residual deformation of press-fit terminals, so as to solve the problems mentioned in the background art.

[0007] To solve the above-mentioned technical problems, the present invention provides a secondary anti-loosening method for residual deformation of press-fit terminals, comprising the following steps: (1) Preparation of composite energy storage terminal substrate: a metal skeleton, a piezoelectric energy storage layer, a stress energy coupling adjustment layer and a coordination bond functional layer are prepared sequentially to form a four-layer composite structure substrate; the metal skeleton is provided with an arc-shaped stress guiding groove, the piezoelectric energy storage layer is coated on the contact end of the metal skeleton and the surface of the stress guiding groove, the stress energy coupling adjustment layer is a gradient pore structure, and the coordination bond functional layer is a polymer network structure cross-linked with metal ions. (2) Residual potential energy directional anchoring pressing process: The pressing polarization energy storage stress calibration integrated mold is used for the directional storage and anchoring of residual elastic potential energy through the steps of potential energy pre-storage, stress energy calibration, bond energy coupling and slow pressure release. (3) Environmental energy capture triple cycle lock-up trigger: through temperature and humidity cycle trigger energy conversion, mechanical energy is converted into electrical energy, electrical energy drives the directional contraction of the coordination bond functional layer, forming a triple cycle self-reinforcing process of potential energy being converted into electrical energy, electrical energy being converted into bond energy, bond energy being converted into stress, and stress feeding back potential energy.

[0008] Furthermore, the metal skeleton is made of high-strength titanium-copper alloy and formed by precision stamping; the curvature of the arc-shaped stress guide groove is designed according to formula (1): ; in The final design curvature of the arc-shaped stress guide groove, The base radius is 0.3 rad. The stress thermal expansion matching coefficient is 0.05 rad·℃·10⁶. This is the difference in the coefficients of thermal expansion between the terminal and the mating component. The maximum temperature variation range in the application scenario; the depth of the stress guiding groove is 0.3 to 0.5 mm.

[0009] Furthermore, the piezoelectric energy storage layer uses a polyvinylidene fluoride trifluoroethylene copolymer with a molar ratio of 70:30, and a coating with a thickness of 8 to 12 μm is formed by solution casting process. In the solution casting process, the solvent is N,N-dimethylformamide, the solid content of the solution is 15 wt%, and the coating speed is 20 mm / s. A segmented polarization process is adopted, first applying a 50 kV / cm electric field at 25℃ for pre-polarization for 10 min, then raising the temperature to 80℃ and holding for 20 min, and finally applying a 100 kV / cm electric field for final polarization treatment.

[0010] Furthermore, the stress energy coupling regulating layer is a composite system of modified epoxy resin and 10wt% micron-sized expanded graphite; a dense region near the piezoelectric layer and a loose region near the coordination bond layer are formed by controlling the coating through a nylon template, with a pore size gradient of 2 to 5 μm for the nylon template; it is cured at 120℃ for 15 min; the electrical energy conduction efficiency of the regulating layer is designed according to formula (2): ; in The electrical energy conduction efficiency of the stress energy coupling conditioning layer; The base conductivity when the loose region is not expanded; is the volume expansion rate of the loose region.

[0011] Furthermore, the coordination bond functional layer is a zinc ion crosslinked polyaspartic acid network with a PASP molecular weight of 5000 Da. An in-situ polymerization process is adopted, first coating with an 8wt% PASP aqueous solution, then spraying with a 0.5mol / L ZnCl2 solution and reacting at 25℃ for 10min to form a coating with a thickness of 5 to 8μm. 1wt% γ-aminopropyltriethoxysilane is added to the PASP aqueous solution as a coupling agent.

[0012] Furthermore, the main body of the integrated mold is made of Cr12MoV alloy steel, and its hardness is HRC60 to 62 after quenching. The mold includes a three-section pressure module, an electric field generation module with built-in high-voltage power supply, and a pressure sensing unit and a miniature displacement sensor.

[0013] Furthermore, in the stepwise process of pressure-bonding energy storage: during the potential energy pre-storage stage, a pressure of 30 to 35 MPa and an electric field of 50 kV / cm are applied, and the pressure is maintained when the stress at the contact end reaches 18 to 20 MPa; during the stress energy calibration stage, the electric field strength is dynamically adjusted so that the angle between the polarization direction of the piezoelectric layer and the direction of the residual stress is ≤5°; during the bond energy coupling stage, the pressure is reduced to 15 to 20 MPa and maintained for 10 s; during the depressurization stage, the pressure is slowly depressurized at a rate of 3 MPa / s.

[0014] Furthermore, in the triple-cycle lock-up triggering of environmental energy capture, temperature changes cause the piezoelectric layer to convert into instantaneous electrical energy of 0.5 to 1.2V through the inverse piezoelectric effect, and humidity changes dynamically adjust the electrical energy conduction efficiency through the volume expansion of the loose region of the regulating layer; the electrical energy is transmitted to the coordination bond functional layer through the dense region of the regulating layer, activating coordination bond recombination and causing the functional layer to shrink in volume, maintaining the contact pressure at 95% to 105% of the rated value; the chemical energy released by the coordination bond recombination feeds back into the piezoelectric energy storage layer, forming a cycle of self-reinforcing.

[0015] Compared with the prior art, the beneficial effects of the present invention are: 1. Residual deformation is transformed from a defect into an active anti-loosening force: Through the quantitative design of the arc-shaped stress guiding groove of the metal skeleton (Formula 1), the residual elastic potential energy after the terminal is pressed is directionally stored and guided to the contact end, which completely solves the long-term loosening problem caused by the disordered release of residual stress and realizes the resource utilization of residual deformation.

[0016] 2. Temperature and humidity cycles transform loosening causes into anti-loosening aids: Temperature changes convert mechanical energy into 0.5-1.2V instantaneous electrical energy through the inverse piezoelectric effect, while humidity changes dynamically optimize the electrical energy conduction efficiency through the gradient pore adjustment layer (Formula 2). The dual effect drives the directional tightening of the coordination bond functional layer, stabilizing the contact pressure at 95%-105% of the rated value, thus solving the dual problems of thermal expansion coefficient differences and humidity-induced mechanical attenuation.

[0017] 3. No need for additional anti-loosening components and secondary processing: The integrated composite structure (metal skeleton + piezoelectric energy storage layer + adjustment layer + aligning key functional layer) eliminates the need for external components such as elastic washers and anti-loosening nuts. Pressing, polarization, and energy storage are completed in one step, avoiding secondary pressing or gluing processes, reducing material and manufacturing costs, and improving assembly efficiency.

[0018] 4. Achieve a self-reinforcing anti-loosening effect: Form a triple cycle of potential energy conversion into electrical energy, electrical energy conversion into bond energy, bond energy conversion into stress, and stress feeding back into potential energy. The chemical energy released by the recombination of coordination bonds feeds back into the piezoelectric energy storage layer, making the terminals tighter with use, avoiding deformation caused by excessive tightening and gradual loosening under dynamic working conditions, and significantly extending service life.

[0019] 5. Multi-dimensional functional synergy enhancement: It has a loosening warning function (through piezoelectric layer voltage signal feedback) without the need for additional sensing elements; the coordination bond functional layer can autonomously repair micro-cracks and oxide layer gaps at the contact interface, and the regulating layer adsorbs water vapor to prevent metal skeleton corrosion, solving the insulation degradation problem under high humidity conditions; the gradient pore structure realizes anti-loosening self-cleaning, adsorbs and removes tiny impurities at the contact interface, reducing maintenance and cleaning procedures; the weak current of the piezoelectric effect and water vapor adsorption form a dual antibacterial effect, reducing the risk of microbial corrosion.

[0020] 6. High feasibility for mass production and low energy loss: All processes use conventional industry equipment. Existing factories only need to modify the pressing mold (add electric field module and sensing unit) to start mass production, with low modification cost; the composite structure significantly suppresses residual potential energy and environmental energy loss, the contact resistance is stable for a long time, avoids the risk of circuit failure, and is suitable for complex working conditions such as automotive engine compartments and outdoor electronic equipment. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the secondary anti-loosening method for residual deformation of the press-fit terminal according to the present invention. Detailed Implementation

[0022] 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.

[0023] Please see Figure 1 The present invention provides a technical solution: See Figure 1 The following is an example of a secondary anti-loosening method for residual deformation of press-fit terminals: I. Preparation of composite energy storage terminal substrate: 1. Metal framework preparation: High-strength titanium-copper alloy (Cu-4.5Ti) is selected and formed by precision stamping (the stamping equipment is a conventional CNC punch press). An arc-shaped stress guide groove is reserved at the contact end. Its core design lies in the precise calculation of the curvature through a quantitative formula to ensure that the residual stress is pre-matched with the thermal expansion deformation of the terminal mating parts, thus avoiding disordered stress release.

[0024] Since the curvature of the stress guiding groove directly determines the directional transmission efficiency of residual stress, it is necessary to perform quantitative design based on the difference in thermal expansion coefficients between the terminal and the wire / substrate. Therefore, formula (1) is proposed: ; in: The final design curvature of the arc-shaped stress guide groove is the core parameter to ensure the directional distribution of stress. : Basic radius, with a value of 0.3 rad, is the minimum fitting radius for the initial contact between the terminal and the mating part; Stress thermal expansion matching coefficient, preset value is 0.05 rad・℃・10 6 The final value can be further verified through a large number of experiments to ensure the synergy between stress and thermal expansion deformation; The difference in the coefficient of thermal expansion between the terminal metal frame and the wire / substrate needs to be determined based on the material of the mating components in the actual application scenario. For example, if the terminal is Cu-4.5Ti (coefficient of thermal expansion 16.5×10⁻⁶), the difference needs to be determined based on the material of the mating components in the actual application scenario. -6 / ℃), the substrate is epoxy resin (thermal expansion coefficient 5.5×10), -6 At / ℃), =11×10 -6 / ℃; The maximum temperature variation range in terminal application scenarios, such as 190℃ (-50℃ to 140℃) in the automotive engine compartment scenario.

[0025] According to formula (1), the groove depth of the arc-shaped stress guide groove is calculated to be 0.3 to 0.5 mm. This structure can be achieved by adding an arc-shaped molding block to a conventional stamping die without the need for special equipment.

[0026] 2. Preparation of piezoelectric energy storage layer: The material is selected as polyvinylidene fluoride-trifluoroethylene (PVDF-TrFE) copolymer, with a molar ratio controlled at 70:30 to ensure the stability of piezoelectric properties; Solution casting process is adopted: N,N dimethylformamide (DMF) is selected as the solvent. PVDF-TrFE powder is dissolved in DMF to prepare a solution with a solid content of 15wt%. The solution is then coated on the inner side of the contact end of the metal skeleton and the surface of the stress guide groove using a doctor blade coating machine at a coating speed of 20mm / s to form a coating with a thickness of 8 to 12μm. A segmented polarization process is employed: first, a 50 kV / cm electric field is applied at room temperature (25℃) for pre-polarization for 10 minutes; then, the coating is placed in an oven and heated to 80℃ for 20 minutes, while simultaneously increasing the electric field strength to 100 kV / cm for final polarization. This process can increase the piezoelectric coefficient d of the piezoelectric layer. 31 The performance is improved, and the polarization stability is enhanced, solving the problem of low energy conversion efficiency caused by single polarization.

[0027] 3. Fabrication of the stress-energy coupling modulation layer: Material system: A composite system of modified epoxy resin (E-51) and micron-sized expanded graphite (particle size 5 to 10 μm) was selected, with the expanded graphite addition amount being 10 wt%. Mixing process: Add E-51 epoxy resin and expanded graphite to a conventional mechanical stirrer and stir at 800 r / min for 30 min to ensure uniform mixing and no agglomeration. Gradient pore structure construction: A nylon template (pore size gradient of 2 to 5 μm) was used to control the coating process. The template was fabricated using a conventional laser drilling machine. During coating, the template was attached to the surface of the piezoelectric energy storage layer, and the composite slurry was filled into the template pores using a scraping method, forming a gradient structure with a dense region near the piezoelectric layer and a loose region near the coordination bond layer. This structure mimics the dual function of leaf veins for transport and storage, with the dense region ensuring efficient electrical energy conduction and the loose region enabling humidity-responsive pore opening and closing. Curing treatment: Place the coated substrate in an oven and keep it at 120°C for 15 minutes to allow the epoxy resin and expanded graphite to form a physically interwoven and chemically bonded structure, while retaining the humidity-responsive expansion characteristics of the expanded graphite.

[0028] To achieve a precise match between humidity changes and electrical energy conduction, it is necessary to quantify the relationship between the volume expansion rate of the loose area and the electrical energy conduction efficiency, and formula (2) is proposed: ; in: The electrical energy conduction efficiency of the stress-energy coupling conditioning layer directly affects the energy conversion effect of the energy cycle. The base conduction efficiency when the loose zone is not expanded is taken as 60%, which is determined by the material properties of the dense zone of the conditioning layer. The volume expansion rate of the loose zone is caused by changes in environmental humidity and satisfies the following conditions: ; This represents the change in ambient humidity. This relationship needs to be verified experimentally to ensure the synergy between humidity response and electrical energy conduction.

[0029] The quantitative correlation between formula (2) and formula (1) is achieved through the gap state of the terminal mating parts: In formula (1) The difference in thermal expansion coefficients determines the initial gap between the terminal and the mating component, as well as the gap change caused by temperature variations. This gap change directly affects the contact efficiency of the ambient humidity and the loose area of ​​the conditioning layer, thereby regulating the... The response amplitude is determined to achieve a logical closed loop of stress pre-calibration (Formula 1), humidity response, and electrical energy conduction (Formula 2), ensuring the parameter coordination of the entire technical solution.

[0030] 4. Preparation of coordinate bond functional layers: Material system: Zinc ions (Zn) are selected. 2+ A cross-linked polyaspartic acid (PASP) network, with the PASP molecular weight controlled at 5000 Da, ensures the dynamic recombination ability of the molecular chains; In-situ polymerization process: ① Dissolve PASP powder in deionized water to prepare an 8wt% PASP aqueous solution, and coat it onto the surface of the conditioning layer using a spray coating machine (conventional equipment) with a coating amount of 0.5 g / cm²; ② Load a 0.5 mol / L ZnCl2 solution into a conventional spraying device and spray it onto the PASP coating surface at a pressure of 0.2 MPa. React at room temperature (25℃) for 10 min to form a coordination bond network. The final coating thickness is 5 to 8 μm. Interface enhancement: 1 wt% γ-aminopropyltriethoxysilane (KH-550) was added to an aqueous PASP solution as a coupling agent and mixed thoroughly using conventional stirring equipment. This coupling agent can increase the interfacial bonding energy between the coordination bond layer and the regulating layer by 60% without affecting Zn. 2+ The ability to dynamically recombine with PASP molecular chains.

[0031] II. Residual Potential Energy Oriented Anchoring and Pressing Process: This step is achieved by pressing and bonding an integrated mold for polarized energy storage stress calibration. The mold can be modified from a conventional pressing mold to ensure the feasibility of industrial mass production.

[0032] 1. Integrated mold: A customized integrated mold for pressure-bonded polarization energy storage stress calibration is used. The main body of the mold is made of Cr12MoV alloy steel, which has been hardened (hardness HRC60 to 62). The specific modification plan is as follows: Pressure module: It adopts a three-section structure (root, middle and contact end), each module is independently controllable, the pressure adjustment range is 0 to 50MPa, and it is driven by a conventional hydraulic system; Electric field generating module: Built-in high voltage power supply with a voltage adjustment range of 0 to 100kV / cm, connected to the conductive insert of the upper mold through wires to achieve uniform application of electric field; Sensing and feedback module: Built-in pressure sensing unit (accuracy ±0.1MPa) and miniature displacement sensor (accuracy ±0.001mm), response time ≤10ms. Sensor signals are transmitted to the controller through a conventional data acquisition card to achieve real-time feedback adjustment.

[0033] 2. Step-by-step process for bridging energy storage: First stage (potential energy pre-storage): The composite energy storage substrate is placed into the mold, and the hydraulic system is started to apply a pressure of 30 to 35 MPa to cause the metal skeleton to undergo plastic deformation; at the same time, the electric field generation module is turned on to apply an electric field of 50 kV / cm to synchronously polarize the piezoelectric energy storage layer; at this time, the stress guiding groove guides the residual elastic potential energy to concentrate at the contact end according to the design curvature of formula (1); the pressure sensing unit monitors the stress at the contact end in real time, and when the stress reaches 18 to 20 MPa (this threshold is 1.2 times the rated contact pressure of the terminal to ensure sufficient potential energy reserve), the controller triggers the mold pressure to hold.

[0034] The second stage (stress energy calibration): Keep the pressure constant, start the stress feedback adjustment module, monitor the micro-deformation of the terminal contact end through the micro displacement sensor, and dynamically adjust the electric field strength (adjustment range ±5kV / cm) to make the polarization direction of the piezoelectric layer completely consistent with the direction of residual stress (angle ≤5°) to avoid mismatch of energy conversion direction.

[0035] The third stage (bond coupling): The pressure is reduced to 15 to 20 MPa by the hydraulic system and maintained for 10 seconds; the dense area of ​​the regulating layer conducts the electric field, so that the coordination bond functional layer is initially cross-linked, forming the initial coupling of potential energy, electrical energy and bond energy. At this time, the loose area is in an incompletely closed state, reserving space for humidity response.

[0036] Depressurization phase: Depressurization is slow at a rate of 3MPa / s (the depressurization rate is controlled by the throttle valve of the hydraulic system). The piezoelectric energy storage layer remains polarized under residual stress, and the coordination bond functional layer is in a semi-stable state. The gradient porosity structure of the regulating layer locks in some air, forming a micro-pressure buffer to avoid stress rebound caused by excessive depressurization, thus completing the energy storage anchoring.

[0037] III. The environment can capture triple-loop lock-off triggers: This step triggers energy conversion and circulation through temperature and humidity cycles, requiring no additional power and relying entirely on the synergistic effect of environmental loads and composite structures.

[0038] 1. Temperature and humidity cycle triggering and energy conversion: Temperature Response: When the ambient temperature changes, the terminals and mating parts undergo relative deformation due to the difference in their coefficients of thermal expansion. The stress-directing grooves in the metal skeleton (designed according to Formula 1) guide this deformation to the piezoelectric energy storage layer. The piezoelectric layer converts mechanical energy into instantaneous electrical energy of 0.5 to 1.2V through the inverse piezoelectric effect. The synergistic effect of the stress-directing grooves and the piezoelectric layer improves the energy conversion efficiency.

[0039] Humidity response: When the ambient humidity changes, the loose areas of the conditioning layer expand in volume due to the absorption of water by the expanded graphite. According to formula (2), the volume expansion rate is... With humidity change Dynamic adjustment: When humidity increases, Increased porosity leads to pore closure in the loose zone, thus improving electrical energy conduction efficiency. Simultaneous expansion and the resulting micro-pressure push the coordination bond layer closer to the mating interface; when humidity decreases... The size of the pores is reduced, and the pores open to release excess heat, thus avoiding polarization decay caused by overheating of the piezoelectric layer.

[0040] 2. Electrical drive and coordinate bond compression: Power transmission: Power is transmitted to the coordination bond functional layer through the dense region (low resistance channel) of the regulating layer, reducing transmission loss; Targeted compression: Electrically activated Zn 2+ The coordination bonds of the PASP molecular chain recombine, causing the functional layer to shrink and generate directional clamping force; the regulating layer dynamically adjusts the power transmission rate based on residual stress feedback (indirectly obtained through the stress sensing characteristics of the piezoelectric layer), so that the contact pressure is always maintained at 95% to 105% of the rated value.

[0041] 3. Triple-cycle self-reinforcing: Energy feedback: The chemical energy released during the coordination bond recombination process feeds back to the piezoelectric energy storage layer through the dense region of the regulating layer, maintaining its polarization stability; Cyclic gain: During the next temperature and humidity cycle, the piezoelectric layer can capture more environmental energy due to its stable polarization, driving the coordination bonds to further tighten precisely, forming a triple cycle of potential energy converted into electrical energy, electrical energy converted into bond energy, bond energy converted into stress, and stress feeding back into potential energy, achieving a self-reinforcing effect that gets tighter with use.

[0042] IV. Full-chain functional enhancement mechanism: 1. Loosening warning and adaptive control: Early warning implementation: When the contact pressure decreases, the deformation amplitude of the piezoelectric energy storage layer increases, and the peak voltage of the output power increases synchronously. An external conventional voltage sensor can capture this signal to realize the loosening warning without the need to add additional sensing elements.

[0043] Adaptive compensation: High voltage triggers the deep compression of the ligature key functional layer, while the loose area of ​​the adjustment layer expands to generate auxiliary clamping force, providing double protection to restore the contact pressure to the rated range.

[0044] 2. Interface damage self-healing and environmental adaptation: Self-repair: Under the stimulation of electrical energy cycling, the molecular chains of the coordination bond functional layer have dynamic fluidity, which can autonomously repair the micro-cracks and oxide layer gaps at the contact interface. The KH-550 coupling agent in the regulating layer can promote coordination bond recombination and further improve the repair effect.

[0045] Environmental adaptability: The expanded graphite in the conditioning layer can adsorb trace amounts of water vapor in the environment, preventing water vapor from directly corroding the metal skeleton; when the ambient temperature rises, the adsorbed water vapor will be released, providing a suitable weak humidity environment for coordination bond recombination, effectively solving the problem of insulation degradation under high humidity conditions.

[0046] 3. Energy loss suppression and process adaptation: Loss control: The composite structure consisting of a piezoelectric energy storage layer, a stress energy coupling adjustment layer, and a coordination bond functional layer can significantly suppress the loss of residual potential energy and environmental energy, with a loss level far lower than that of traditional terminals.

[0047] Mass production feasibility: All processes use industry-standard equipment and do not rely on cutting-edge precision instruments; ordinary terminal production plants only need to modify the existing pressing molds by adding electric field modules and sensing units to achieve mass production. The modification cost is low and the overall increase in production cost is far lower than the traditional solution of adding extra anti-loosening components.

[0048] Summarize: Residual elastic potential energy is transformed from defects into active anti-loosening power, and its directional utilization is achieved through quantitative design, completely solving the loosening problem caused by the disordered release of residual stress. Temperature and humidity cycles are no longer the cause of loosening. Temperature changes are converted into pressing electrical energy through the inverse piezoelectric effect, and humidity changes are optimized for energy conduction and pressure matching through quantitative matching, solving the dual antagonism of differences in thermal expansion coefficients and humidity-induced mechanical attenuation. The integrated structural design eliminates the need for additional anti-loosening components. Pressing, polarization, and energy storage are completed in one step, avoiding secondary processing, effectively improving assembly efficiency and reducing manufacturing costs. Meanwhile, it achieves an unconventional effect of cyclic locking and self-reinforcing. The precise matching of stress and energy avoids terminal deformation caused by excessive tightening and gradual loosening under dynamic conditions. The multi-dimensional synergistic effect is significant, the contact resistance remains stable over a long period of time, and the risk of circuit failure is completely avoided. It has excellent environmental adaptability in complex working conditions such as automotive engine compartments and outdoor electronic equipment, and the service life of the terminals is greatly extended. Moreover, the weak current of the piezoelectric effect and the adsorption of water vapor in the regulating layer form a dual antibacterial effect, reducing the risk of microbial corrosion. It also has the dual functions of anti-loosening and self-cleaning. The gradient pore structure of the regulating layer can adsorb tiny impurities on the contact interface to prevent the gap from increasing. The adsorbed impurities can be discharged through the weak vibration of the piezoelectric layer during energy cycle, reducing the cleaning process of terminal maintenance.

Claims

1. A secondary locking method for crimped terminal residual deformation, characterized in that, The method comprises the following steps: (1) composite energy storage terminal substrate preparation: sequentially prepare a metal skeleton, a piezoelectric energy storage layer, a stress energy coupling adjustment layer and a coordination bond functional layer to form a four-layer composite structure substrate; the metal skeleton is provided with an arc-shaped stress guide groove, the piezoelectric energy storage layer is coated on the contact end and the surface of the stress guide groove of the metal skeleton, the stress energy coupling adjustment layer has a gradient pore structure, and the coordination bond functional layer has a polymer network structure cross-linked by metal ions; (2) residual potential energy directional anchoring pressing process: an integrated mold for polarization energy storage stress calibration is used to store and anchor the residual elastic potential energy through the steps of potential energy pre-storage, stress energy calibration, bond energy coupling and slow pressure relief; (3) environmental energy capture triple cycle locking trigger: mechanical energy is converted into electrical energy through temperature and humidity cycle trigger energy conversion, and the electrical energy drives the coordination bond functional layer to be directionally contracted to form a triple cycle self-strengthening of potential energy converted into electrical energy, electrical energy converted into bond energy, bond energy converted into stress, and stress feeding back potential energy.

2. The press-fit terminal residual deformation secondary lockout method of claim 1 wherein: The metal skeleton is made of high-strength titanium-copper alloy through precise stamping process; the arc of the arc-shaped stress guide groove is designed according to formula (1): ； wherein is the final design arc of the arc-shaped stress guide groove, is the base arc of 0.3 rad, is the stress thermal expansion matching coefficient of 0.05 rad·℃·106, is the difference in thermal expansion coefficients between the terminal and the mating piece, is the maximum temperature change range in the application scenario; the groove depth of the stress guide groove is 0.3 to 0.5 mm.

3. The press-fit terminal residual deformation secondary lockout method of claim 1 wherein: The piezoelectric energy storage layer is made of polyvinylidene fluoride-trifluoroethylene copolymer with a molar ratio of 70:30, and is coated to form a coating with a thickness of 8 to 12 μm by solution casting process; in the solution casting process, the solvent is N,N-dimethylformamide, the solid content of the solution is 15 wt%, and the coating speed is 20 mm / s; a segmented polarization process is used, first pre-polarize at 25℃ for 10 min under an electric field of 50 kV / cm, then heat to 80℃ for 20 min and finally polarize under an electric field of 100 kV / cm.

4. The press-fit terminal residual deformation secondary lockout method of claim 1 wherein: The stress energy coupling adjustment layer is a composite system of modified epoxy resin and 10 wt% micron-sized expanded graphite; a dense area close to the piezoelectric layer and a loose area close to the coordination bond layer are formed by coating through a nylon template, and the nylon template has a pore size gradient of 2 to 5 μm; the adjustment layer is cured at 120℃ for 15 min; the electrical energy transmission efficiency of the adjustment layer is designed according to formula (2): ； wherein is the electrical energy conduction efficiency of the stress energy coupling adjustment layer; is the base conduction efficiency of the loose region when not expanded; is the volumetric expansion rate of the loose region.

5. The press-fit terminal residual deformation secondary lockout method of claim 1 wherein: The coordination bond functional layer is a polyaspartic acid network cross-linked by zinc ions, and the molecular weight of PASP is 5000 Da; an in-situ polymerization process is used, first coat 8 wt% PASP aqueous solution, then spray 0.5 mol / L ZnCl2 solution and react at 25℃ for 10 min to form a coating with a thickness of 5 to 8 μm; 1 wt% γ-aminopropyl triethoxysilane is added to the PASP aqueous solution as a coupling agent.

6. The press-fit terminal residual set method of claim 1, wherein: The main material of the integrated mold is Cr12MoV alloy steel, and the hardness after quenching treatment is HRC60 to 62; the mold comprises a three-section pressure module, an electric field generating module with a built-in high-voltage power supply, and a pressure sensing unit and a micro displacement sensor.

7. The press-fit terminal residual set method of claim 1, wherein: In the pressing energy storage step-by-step process: in the potential energy pre-storage stage, a pressure of 30 to 35 MPa and an electric field of 50 kV / cm are applied, and when the contact end stress reaches 18 to 20 MPa, the pressure is maintained; In the stress energy calibration stage, the electric field intensity is dynamically adjusted so that the angle between the polarization direction of the piezoelectric layer and the residual stress direction is ≤5°; in the bond energy coupling stage, the pressure is reduced to 15 to 20 MPa and maintained for 10 s; The pressure relief phase is slowly released at a rate of 3 MPa / s.

8. The press-fit terminal residual set method of claim 1, wherein: In the environmental energy capture triple-loop lock trigger, temperature changes cause the piezoelectric layer to convert into 0.5-1.2V transient electrical energy through the inverse piezoelectric effect, and humidity changes dynamically adjust the electrical energy transmission efficiency by adjusting the volume expansion of the loose area of the adjusting layer; the electrical energy is transmitted to the coordination bond functional layer through the dense area of the adjusting layer, the activation of the coordination bond recombination causes the volume of the functional layer to shrink, keeping the contact pressure at 95%-105% of the rated value; the chemical energy released by the coordination bond recombination feeds back to the piezoelectric energy storage layer, forming a cycle of self-strengthening.

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