New energy relay shell and additive mixing manufacturing method thereof

Abstract

The invention relates to the technical field of new energy automobile accessories, in particular to a new energy relay shell and an additive mixing manufacturing method thereof. Performing array printing on the outer surface of the functional skeleton to generate a preset directional deformation assembly, and performing integrated printing in the functional skeleton to generate a three-dimensional variable cross-section arc extinguishing flow channel; scanning and activating the surface of the functional skeleton by adopting a plasma beam, and then depositing a silane coupling agent layer; putting the functional framework into an injection mold, and injecting a thermoplastic engineering plastic melt into the mold; the pressure of the mold cavity is maintained until the temperature of the injection molding layer is reduced to be lower than the crystallization temperature, the deformed preset directional deformation assembly is fastened through the volume shrinkage rate of the injection molding layer, the thin plate is induced to be directionally bent through the heat flow deformation technology, and dynamic mechanical counterforce balance is formed through the rebound potential energy of the thin plate and the shrinkage force of the injection molding layer. And the IP67 protection requirement of the high-voltage relay of the new energy automobile is met.

Description

Technical Field

[0001] This invention relates to the technical field of new energy vehicle parts, and specifically to a new energy relay housing and its additive manufacturing method. Background Technology

[0002] In the field of new energy, such as electric vehicles and renewable energy systems, relays, as key electronic control components, require housings with high insulation, high temperature resistance, crack resistance, and high airtightness to ensure reliable operation under high-voltage, high-frequency switching conditions. Traditional relay housing manufacturing mainly relies on injection molding or metal die casting processes. While these methods are mature, they have many limitations. Injection molding often uses a single thermoplastic, making the housing prone to thermal stress cracking under extreme temperature cycles (e.g., -40℃ to 150℃), and the bonding strength is insufficient to resist arc creep. Metal die casting provides good mechanical strength, but it is complex to process, costly, and requires additional coating treatment for insulation, which can easily lead to interface delamination. Furthermore, traditional processes struggle to achieve complex internal structures, such as arc-extinguishing channels, resulting in poor arc flame conduction and increasing the risk of external circuit contamination. As new energy equipment develops towards lightweight and intelligent designs, the demand for personalized design and rapid iteration of relay housings is increasing, and the reliance on molds and long lead times in traditional manufacturing have become bottlenecks.

[0003] In existing technologies, some patent documents attempt to improve shell performance through hybrid manufacturing. US Patent US20140277664A1 discloses a method for manufacturing injection molds using 3D printing technology, generating mold prototypes from reverse CAD files to achieve rapid prototype verification. Analysis of this technology shows that its main advantage lies in reducing mold manufacturing time and cost, making it suitable for small-batch production. However, this patent only focuses on the design and printing of the mold itself, without addressing the interface optimization between the insert and the injection layer. This leads to microscopic gaps at the interface, especially under high temperature and pressure conditions, where the interface strength is insufficient to withstand mechanical stress and thermal shock, posing a risk of cracking. Furthermore, this method does not consider relay-specific applications, such as the complex geometry of arc-extinguishing channels, limiting its application in high-voltage electronic control components.

[0004] Another related patent, US20160136897A1, discloses a method for additive manufacturing of composite materials, using a coaxial extruder to form a core and cladding structure, achieving multi-material composites. This technology improves the strength and functionality of components through a layering process and is suitable for manufacturing lightweight composite shells. Analyzing its technology, this patent emphasizes core-cladding interface fusion but relies on material compatibility, neglecting surface activation treatment. This leads to uneven melt penetration during injection molding and low interfacial bonding strength (typically <30MPa). Furthermore, this method does not integrate deformable components or two-stage injection control, making it difficult to achieve a dynamic locking mechanism. Gaps are easily generated during the cooling and shrinkage stage, affecting airtightness and arc resistance. These problems are particularly prominent in new energy relay shells, potentially leading to increased arc creep and leakage rates (>50Pa·cm³ / s).

[0005] The paper "Freeform Injection Molding of Functional Ceramics by Hybrid Additive Manufacturing" proposes a hybrid approach using 3D-printed sacrificial molds for ceramic injection molding. This technology achieves complex shapes through additive manufacturing; however, analysis shows that while suitable for ceramic components, it has poor compatibility with thermoplastics and lacks directional deformation components or arc-quenching channel design, leading to easy delamination at the interface within the polymer-based shell and insufficient mechanical strength to withstand a 50 kPa pressure test. A common problem with these existing technologies is the lack of interface reinforcement and internal functional integration for relay shells, making it difficult to address issues such as thermal stress cracking, weak bonding, and poor arc conduction. Summary of the Invention

[0006] Therefore, the purpose of this invention is to provide a new energy relay housing and its additive hybrid manufacturing method, so as to solve the technical problems in the prior art, such as the inability of traditional injection molding to form complex arc extinguishing structures, and the poor interfacial airtightness, low bonding strength, and difficulty in resisting thermal expansion and contraction stress cracking in conventional hybrid manufacturing.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A method for additive hybrid manufacturing of a new energy relay housing includes the following sequential steps:

[0009] S1. Additive Manufacturing Functional Skeleton: A functional skeleton made of high-temperature resistant insulating material is formed by photopolymerization; a pre-defined directional deformation component is arrayed and printed on the outer surface of the functional skeleton; and a three-dimensional variable cross-section arc-extinguishing flow channel is integrally printed inside the functional skeleton.

[0010] S2. Interface surface modification: The surface of the functional framework is scanned and activated using a plasma beam, followed by deposition of a silane coupling agent layer;

[0011] S3. In-mold precision positioning: The functional skeleton is placed into the injection mold, and positioning is achieved by the mechanical crushing fit between the collapsible support unit on the surface of the skeleton and the inner wall of the mold cavity.

[0012] S4, Two-stage injection molding: Injecting thermoplastic engineering plastic melt into the mold; in the first stage, controlling the melt flow front to cover the preset oriented deformation component under a limited flow rate and filling volume; in the second stage, after the melt fills to a set threshold, switching to high pressure mode, using dynamic pressure to change the geometry of the preset oriented deformation component;

[0013] S5 Pressure Holding and Cold Solidification Locking: Maintain the mold cavity pressure until the injection layer temperature drops below the crystallization temperature, and use the volume shrinkage rate of the injection layer to fasten the pre-defined directional deformation component that has been deformed.

[0014] The present invention is further configured such that: the preset directional deformation component is an array of thin plates distributed around the outer wall of the skeleton, and its geometric structural parameters are as follows:

[0015] Thickness gradient: The thickness at the root of the sheet is 0.3 mm to 0.6 mm, and the thickness at the end is 0.1 mm to 0.2 mm;

[0016] Growth angle: The angle θ between the thin plate and the skeleton reference plane is 30 degrees to 60 degrees, and the tilting direction is opposite to the melt filling direction in step S4;

[0017] Array spacing: The spacing D between adjacent thin plates is 1.0 mm to 2.0 mm, which is greater than the minimum flow layer thickness of the injection melt.

[0018] The present invention is further configured such that the process parameters for interface surface modification in step S2 are characterized as follows:

[0019] Plasma scanning: Atmospheric pressure low-temperature plasma beam is used, the scanning speed is set to 5 mm / s to 10 mm / s, and the distance between the nozzle and the skeleton surface is 10 mm to 15 mm;

[0020] Coupling agent heat treatment: After spraying a 3% to 5% silane coupling agent solution, heat it in an environment of 80°C to 100°C for 10 to 15 minutes.

[0021] The present invention is further configured such that the geometric structural features of the collapsible support unit in step S3 are:

[0022] Cross-sectional shape: It has a hollow arch bridge-shaped or hemispherical thin-walled shell structure with a wall thickness of 0.2 mm to 0.3 mm;

[0023] Interference fit amount: The height of the support unit in its free state exceeds the nominal size of the mold cavity by 0.05 mm to 0.15 mm;

[0024] Positioning state: In the mold-closed state, the top of the support unit undergoes plastic collapse deformation, and the amount of deformation is equal to the interference fit amount.

[0025] The present invention is further configured such that the specific process control parameters for the first stage in step S4 are:

[0026] Temperature field construction: The injection melt temperature is maintained at 250°C to 280°C, and the mold temperature is controlled at 60°C to 80°C to create a controlled transient temperature difference on the component surface;

[0027] Laminar flow propulsion: The linear propulsion speed of the melt in the mold cavity is controlled to be 15 mm / s to 35 mm / s;

[0028] Thermal softening window: The time span for the melt flow front to contact and cover the preset directional deformation component is controlled to be 0.5 seconds to 2.0 seconds, and this stage continues until the melt filling amount reaches 50% to 70% of the mold cavity volume, ensuring that the component material completes the phase transition from the glassy state to the high elastic state.

[0029] The present invention is further configured such that the specific process control parameters for the second stage in step S4 are:

[0030] V / P switching and pressurization: When the melt filling amount reaches the set threshold, the linear propulsion speed of the melt is increased to 60mm / s to 100mm / s, and the injection pressure is stepped up to 60MPa to 90MPa;

[0031] Compression deformation characteristics: Using the high pressure as a normal load, the component in a highly elastic state is pressed into the gap between the melt and the skeleton;

[0032] Final geometric shaping: At the end of the pressure holding period, the angle between the component and the skeleton surface is compressed to 10 to 15 degrees, and the component exhibits an arc-shaped bending state with a bending radius R of 2.0 to 3.5 times its plate length L.

[0033] The present invention is further configured such that: the pressure holding and cold-fixing locking in step S5 includes:

[0034] Maintain a holding pressure of 60MPa to 90MPa for 3 to 8 seconds to compensate for cooling contraction;

[0035] After the injection molding layer temperature drops below the glass transition temperature, the injection molding layer exhibits a volume shrinkage rate of 1.5% to 2.0%.

[0036] The component recovers its stiffness and springs back as the temperature decreases, and its end is embedded in the shrinking inner wall of the injection-molded layer, forming a mechanical interference fit with an embedding depth of 0.05mm to 0.2mm.

[0037] The present invention is further configured such that, in step S1, the geometric structural features of the three-dimensional variable cross-section arc-extinguishing channel are:

[0038] Self-supporting cross-sectional profile: The cross-section of the flow channel is enclosed by a U-shaped or V-shaped base at the bottom and a self-supporting dome at the top. The angle α between the tangent of the inner wall of the dome and the horizontal construction plane satisfies 45°≤α≤90° throughout the entire length of the flow channel.

[0039] Axial variable diameter structure: The flow channel is connected sequentially along the gas flow direction by a contraction section, a throat section, and an expansion section; the ratio of the cross-sectional area of ​​the throat section to the inlet cross-sectional area of ​​the contraction section is in the range of 0.4 to 0.6;

[0040] Microstructure of the inner wall: The inner wall surface of the flow channel is integrally formed with discontinuous hemispherical or pyramidal micro-protrusions, the height of which is 5μm to 20μm and the spacing between adjacent micro-protrusions is 20μm to 50μm.

[0041] The present invention is further configured such that the material parameters of the functional skeleton and the thermoplastic engineering plastic are characterized as follows:

[0042] Functional skeleton: Ceramic-filled photosensitive resin with a heat distortion temperature greater than 240℃ is selected;

[0043] Thermoplastic engineering plastics: Glass fiber reinforced polybutylene terephthalate or nylon are selected;

[0044] Thermal compatibility: Under the temperature and pressure conditions of the injection molding holding stage, the compression deformation of the functional skeleton body is less than 0.05 mm.

[0045] A new energy relay housing includes an internal functional frame and an external injection-molded layer;

[0046] At the interface between the two, the thin plate structure on the surface of the functional skeleton is encapsulated in the injection molding layer in an arc-shaped bending state, and the tip of the thin plate structure forms a mechanical interlock with the injection molding layer.

[0047] Compared with the shortcomings of the prior art, the beneficial effects of the present invention are as follows:

[0048] Thermorheological processes induce directional bending in the thin sheet, utilizing the sheet's springback potential energy to create a dynamic mechanical balance with the shrinkage force of the injection molding layer. This prestressed interference fit automatically compensates for gaps caused by thermal expansion and contraction of the material, achieving excellent airtightness (<10 Pa·cm³ / s) and meeting the IP67 protection requirements of high-voltage relays for new energy vehicles. Attached Figure Description

[0049] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0050] Reference Figure 1 The present invention provides a further description of an embodiment of an additive hybrid manufacturing method for a new energy relay housing.

[0051] The first step, additive manufacturing of the functional skeleton: The core component—the functional skeleton—is manufactured using SLA (stereolithography) or DLP (digital photolithography) photopolymerization processes. The selected material is a ceramic-filled photosensitive resin with a heat distortion temperature (HDT) greater than 240℃ (such as Formlabs Rigid 10K or equivalent materials) to ensure that the substrate does not soften or deform during subsequent injection molding.

[0052] The geometric design of the skeleton integrates two key features:

[0053] External Pre-Oriented Deformation Components: This is an array of thin plates distributed around the outer wall of the skeleton. Unlike traditional rigid snap-fits, this component is designed as a "thermally sensitive flexible mechanism." The thin plates are designed with a thickness gradient, with a thickness of 0.3mm to 0.6mm at the root to ensure connection strength, and gradually thinning to 0.1mm to 0.2mm at the ends to improve thermal response speed and bending flexibility. The growth angle θ of the thin plates relative to the skeleton reference plane is set to 30 degrees to 60 degrees, and the tilt direction is opposite to the subsequent melt filling direction. The spacing D between adjacent thin plates is set to 1.0mm to 2.0mm, which is greater than the minimum flow layer thickness of the injection melt (typically around 0.5mm), ensuring that the melt can completely encapsulate each thin plate.

[0054] Internal 3D variable cross-section arc-extinguishing channel: Addressing the challenge of extinguishing high-voltage direct current arcs in new energy sources, the framework features an integrally printed channel formed based on the Design for Additive Manufacturing without Support (DfAM) principle. The channel's cross-section is designed in a teardrop or diamond shape, with the angle α between the tangent of the self-supporting dome at the top and the horizontal plane ranging from 45° to 90°. This design utilizes the self-supporting properties of the photocurable resin, eliminating the need for internal support structures and avoiding the problem of inaccessible supports in closed channels, thus ensuring the original smoothness and unobstructed flow of the channel. The channel includes a contraction section, a throat section, and an expansion section along the axial direction. The throat's cross-sectional area shrinks to 40% to 60% of the inlet, creating a Venturi effect that forces the arc gas velocity to increase by 1.6-2.5 times, rapidly extinguishing the arc. Furthermore, the inner wall of the channel is printed with discontinuous micro-protrusions with a height of 5-20 μm and a spacing of 20-50 μm, significantly increasing the specific surface area for condensing and adsorbing metal vapor.

[0055] The second step, interfacial surface modification: To address the interfacial affinity issue between the photosensitive resin (organic-inorganic composite) and the injection-molded engineering plastic (thermoplastic), the framework undergoes a two-step treatment. First, atmospheric pressure low-temperature plasma beams are used for scanning activation, with the scanning speed controlled at 5 mm / s to 10 mm / s and the nozzle distance from the surface 10 mm to 15 mm, to break surface chemical bonds and introduce hydroxyl groups. Subsequently, a 3% to 5% silane coupling agent solution is sprayed on, and the surface is heated at 80°C to 100°C for 10-15 minutes. This step constructs a nanoscale chemical "bridge" on the framework surface, preventing interfacial micro-delamination during long-term use.

[0056] The third step, precision positioning within the mold: The processed skeleton is placed into the injection mold. Due to the dimensional tolerance of approximately ±0.1mm in 3D printed parts, direct placement into a precision mold can easily cause interference, crushing, or overflow. This problem is solved by using collapsible support units on the skeleton surface. These units are hollow arch-shaped or hemispherical thin-walled shells (wall thickness 0.2-0.3mm), with a designed height exceeding the nominal size of the mold cavity by 0.05mm to 0.15mm (i.e., interference fit). Under the action of the clamping force, the thin-walled shell undergoes controlled plastic collapse deformation, with the deformation amount precisely equal to the interference fit, thereby achieving rigid positioning with zero clearance and effectively preventing the injection melt from overflowing into the non-encapsulated area.

[0057] The fourth step, thermo-mechanical coupled two-stage injection molding: Injecting glass fiber reinforced PBT or PA66 melt into the mold (melt temperature 250-280℃, mold temperature 60-80℃). This process is strictly divided into two physically controlled stages:

[0058] The first stage (preparatory stage of thermal retention): The injection molding machine screw is controlled to advance linearly at a low speed of 15mm / s to 35mm / s, and the injection pressure is limited to 20-35MPa. This stage is not only for filling, but also for establishing a temperature field. The time span for the melt flow front to contact and cover the sheet metal assembly is controlled to be 0.5 seconds to 2.0 seconds (ending when the coverage reaches 50%-70%). This brief thermal retention allows the sheet metal material to absorb the heat of the melt, and the temperature rapidly jumps above the glass transition temperature (Tg), completing the phase transition from the glassy state to the elastic state. At this time, the sheet metal softens and has extremely high toughness, and will not break.

[0059] The second stage (dynamic pressure shaping stage): When the filling amount reaches the set threshold (90%-95%), the flow rate is immediately increased to 60-100 mm / s and switched to a high holding pressure of 60-90 MPa. Utilizing the enormous hydraulic kinetic energy as a normal load, the thin plate in a highly elastic (softened) state is pressed against the skeleton surface. Under the fluid impact, the thin plate undergoes a large-angle bend, and the angle between it and the skeleton surface is mechanically pressed and fixed at 10 to 15 degrees.

[0060] Step 5: Pressure Holding and Cooling Locking: Maintain high pressure for 3-8 seconds, followed by cooling. At this point, a crucial mechanical interaction occurs: the outer injection-molded layer cools and crystallizes, resulting in a 1.5%-2.0% volume shrinkage and creating a significant radial clamping force; the internally bent sheet, due to temperature reduction, returns to a glassy state (hardens), generating rebound potential energy to restore its initial angle (30-60 degrees). The shrinkage force and the rebound force counteract each other, forcing the end of the sheet to pierce the shrinking injection-molded layer's inner wall at an acute angle, forming a mechanical interference fit with an embedding depth of 0.05-0.2 mm (i.e., the "barb" effect). Ultimately, the airtightness of the outer shell interface achieves a leakage rate of less than 10 Pa·cm³ / s at 50 kPa pressure.

[0061] Example 1:

[0062] S1 Additive Manufacturing Functional Skeleton: A ceramic-filled photosensitive resin with a heat distortion temperature of 242℃ is used to print the functional skeleton using DLP technology. Pre-defined oriented deformation components (a thin-plate array) are printed on the outer surface of the skeleton. The growth angle θ of the thin plates relative to the skeleton's reference plane is set to 30 degrees, the thickness at the root of the thin plates is 0.3 mm, gradually thinning to 0.1 mm at the ends, and the spacing between adjacent thin plates is 1.0 mm. Simultaneously, a Venturi arc-quenching channel is formed inside the skeleton, with a throat cross-sectional area shrinkage ratio of 0.4.

[0063] S2 Interface and Positioning Treatment: After plasma cleaning and coupling agent heat treatment, the skeleton is placed into the mold. The collapsible support unit at the corner of the skeleton is designed with an interference fit of 0.05mm. After mold closing, the support unit undergoes slight plastic deformation to eliminate gaps.

[0064] S3 Stage 1 Injection Molding (Heat Retention and Softening): Set the injection melt temperature (PBT-GF30) to 260℃ and the mold temperature to 60℃. Injection is initiated, with the linear feed rate precisely controlled at a low speed of 15mm / s and the injection pressure limited to 20MPa. Under these parameters, the melt flow front slowly rises and completely submerges the sheet metal assembly, controlling the contact residence time to reach 2.0 seconds. This relatively long heat conduction time is sufficient for the thin sheet metal (0.1-0.3mm) to fully absorb heat, completely transforming from a glassy state to a soft, highly elastic state.

[0065] S4 Second Stage Injection Molding (Dynamic Pressure Shaping): When the melt fills 90% of the cavity, a process switch is immediately triggered. The injection speed is increased to 60 mm / s, and the holding pressure is set to 60 MPa. Under this dynamic pressure, the softened sheet bends along the melt flow direction and is pressed against the skeleton surface.

[0066] S5 Results Finalization: After pressure holding and cooling, the final angle between the thin plate and the skeleton surface was fixed at 10 degrees through slicing analysis. The thin plate exhibited a large curvature arc with a bending radius R that was 2.0 times its plate length L, forming a tight bonding interface.

[0067] Example 2:

[0068] S1 additive manufacturing functional skeleton: High-performance resin with a heat distortion temperature of 250℃ is selected. The growth angle θ of the printed thin plate array is set to 45 degrees (optimal collapse angle), the root thickness is increased to 0.45mm, the end thickness is 0.15mm, and the spacing is 1.5mm. The cross-sectional area shrinkage ratio of the internal Venturi flow channel throat is 0.5.

[0069] S2 Interface and Positioning Processing: Same as above, but the interference fit of the collapsible support unit is adjusted to 0.10mm to provide more stable in-mold support.

[0070] S3 Stage 1 Injection Molding (Thermal Retention and Softening): Melt temperature 270℃, mold temperature 70℃. Linear feed speed set to medium speed 25mm / s, injection pressure 28MPa. The melt flow front covering the thin sheet is controlled to be completed within 1.2 seconds. Due to the moderate thickness of the thin sheet, this time window ensures material softening while avoiding deformation of the skeleton body caused by prolonged thermal shock.

[0071] S4 Second Stage Injection Molding (Dynamic Pressure Shaping): The process is switched when the fill reaches 92%. The injection speed is linearly accelerated to 80 mm / s, using high momentum to impact the thin sheet, combined with a high holding pressure of 75 MPa, forcing the thin sheet, which is standing at a 45-degree angle, to flex significantly.

[0072] S5 Result Finalization: After cooling and shrinkage, the end of the sheet deeply penetrates the injection molding layer, and the final included angle is locked at 12 degrees. The sheet exhibits a bending radius R that is 2.8 times the sheet length L. Under this structure, the rebound potential energy and the shrinkage clamping force achieve optimal mechanical balance.

[0073] Example 3:

[0074] S1 additive manufacturing functional skeleton: The printed thin-plate array has a growth angle θ set to 60 degrees (to obtain maximum springback potential energy), a root thickness increased to 0.6 mm, an end thickness of 0.2 mm, and a spacing of 2.0 mm. The thicker root design is to withstand higher shear loads.

[0075] S2 Interface and Positioning: The collapsible support unit has an interference fit of 0.15mm to ensure that the skeleton does not shift under heavy injection impact.

[0076] S3 Stage 1 Injection Molding (Heat Retention and Softening): Melt temperature 280℃, mold temperature 80℃. To prevent melt solidification caused by thicker sheet metal, a faster initial velocity of 35mm / s is used for advancement, compressing the contact residence time to 0.5 seconds. Although the time is short, the higher mold and melt temperatures compensate for the heat conduction efficiency, causing the surface of the thick-walled sheet metal to soften rapidly.

[0077] S4 Second Stage Injection Molding (Dynamic Pressure Shaping): The switching is triggered when the fill reaches 95%. The injection speed is explosively increased to 100 mm / s, and an ultimate holding pressure of 90 MPa is applied. The enormous pressure forcibly overcomes the bending stiffness of the thick-walled thin plate, crushing it.

[0078] S5 Result Finalization: The final angle between the thin plate and the skeleton was compressed to 15 degrees. Due to the large initial angle (60 degrees) and the large wall thickness, its springback tendency was extremely strong, and the bending radius R reached 3.5 times the plate length L (the bending was relatively gentle).

[0079] To further illustrate the advanced nature of the technical solution of this invention, the following three sets of comparative experiments were conducted. The material selection of the comparative examples is consistent with that of Example 2 (preferred example), but specific single variable adjustments are made to the structural features or process parameters.

[0080] Comparative Example 1 (Conventional sandblasting process for missing deformable components)

[0081] This comparative example aims to verify the necessity of the "preset directional deformation component (thin plate array)" for interface airtightness.

[0082] Structural differences: The outer surface of the additively manufactured functional skeleton is smooth, without any printed sheets, fins, or undercut structures.

[0083] Process differences: Only the skeleton surface was roughened by sandblasting (Ra 6.3μm) and treated with coupling agent, and then coated using the same injection molding process as in Example 2.

[0084] Technical expectation: To simulate existing technologies that rely solely on surface micro-roughness for bonding and verify whether they can resist micro-gaps caused by injection molding shrinkage.

[0085] Comparative Example 2 (Traditional Rigid Inverted Structure)

[0086] This comparative example aims to verify the advancement of the "thermorheological flexible deformation mechanism" over the traditional "rigid mechanical interlock".

[0087] Structural difference: The flexible thin plate array in Example 2 is replaced with a rigid dovetail groove structure. The dovetail groove wall thickness is 1.5mm (so that the injection molten metal cannot soften and deform it), and the shape is fixed.

[0088] Process differences: The injection molding process is the same as in Example 2.

[0089] Technical expectation: To verify whether the rigid undercut structure can detach its sidewalls and create leakage channels when engineering plastics cool and shrink, as it cannot follow the shrinkage.

[0090] Comparative Example 3 (without using a stepped injection molding process)

[0091] This comparative example aims to verify the key role of the "thermo-mechanical coupled two-stage injection molding process" in protecting thin sheet structures and inducing deformation.

[0092] Structural differences: The skeleton structure is exactly the same as that of Example 2 (including the thin plate array).

[0093] Process differences: The "low-speed heat retention" stage is eliminated, and traditional constant-speed high-pressure injection molding is adopted. The injection speed is set directly to 80mm / s, and the injection pressure is set directly to 75MPa, without segmented control.

[0094] Technical expectation: To verify whether thin-plate components that have not undergone sufficient heat conduction softening will experience root fracture or disordered curling under the direct impact of high-flow-rate melt, leading to failure.

[0095] The details are shown in Table 1 below:

[0096]

[0097] Based on the test data in Table 1, the following conclusions can be drawn:

[0098] Regarding the decisive factors for airtightness (Comparative Example 2 and Comparative Examples 1 and 2):

[0099] Surface roughness alone (Comparative Example 1) is completely insufficient to meet the airtightness requirements of high-voltage relays.

[0100] While the traditional rigid dovetail groove (Comparative Example 2) provides good bonding strength (1200N), its initial airtightness is only 15.6, and it deteriorates rapidly after thermal shock. This is because rigid materials cannot compensate for the crystallization shrinkage of PBT, causing the interface to be pulled apart.

[0101] The present invention utilizes the mechanism of "rebound potential energy of flexible thin plate" to actively compensate for shrinkage gap, which is the key to achieving IP67 level (<10Pa·cm³ / s) airtightness.

[0102] The criticality of process parameters (comparative Example 2 and Comparative Example 3):

[0103] With the same structure, if traditional single-stage high-speed injection molding is used (Comparative Example 3), the airtightness deteriorates and the bonding strength decreases significantly (850N). Cross-section analysis shows that this is because the high-speed melt breaks or misaligns the sheet before it has "thermally softened," thus destroying the pre-designed undercut structure.

[0104] The two-stage process of "low-speed thermal retention + high-speed dynamic pressure shaping" is a necessary condition to ensure the success of thermorheological deformation.

[0105] Overall performance advantages:

[0106] Example 2 (preferred parameters) performed best in all indicators, proving that a growth angle of 30-60 degrees, a thickness of 0.3-0.6 mm, and a specific injection molding parameter window constitute the best combination of technical solutions, achieving a balance between high airtightness, high strength, and weather resistance.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any ordinary changes and substitutions made by those skilled in the art within the scope of the technical solution of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for additive hybrid manufacturing of a new energy relay housing, characterized in that, The steps are as follows, performed in sequence: S1. Additive Manufacturing Functional Skeleton: A functional skeleton made of high-temperature resistant insulating material is formed by photopolymerization; a pre-defined directional deformation component is arrayed and printed on the outer surface of the functional skeleton; and a three-dimensional variable cross-section arc-extinguishing flow channel is integrally printed inside the functional skeleton. S2. Interface surface modification: The surface of the functional framework is scanned and activated using a plasma beam, followed by deposition of a silane coupling agent layer; S3. In-mold precision positioning: The functional skeleton is placed into the injection mold, and positioning is achieved by the mechanical crushing fit between the collapsible support unit on the surface of the skeleton and the inner wall of the mold cavity. S4, Two-stage injection molding: Injecting thermoplastic engineering plastic melt into the mold; in the first stage, controlling the melt flow front to cover the preset directional deformation component under a limited flow rate and filling volume; In the second stage, after the melt is filled to a set threshold, the system switches to high pressure mode and uses dynamic pressure to change the geometry of the preset directional deformation component. S5 Pressure Holding and Cold Solidification Locking: Maintain the mold cavity pressure until the injection layer temperature drops below the crystallization temperature, and use the volume shrinkage rate of the injection layer to fasten the pre-defined directional deformation component that has been deformed.

2. The additive hybrid manufacturing method for a new energy relay housing according to claim 1, characterized in that, In step S1, the preset directional deformation component is an array of thin plates distributed around the outer wall of the skeleton, and its geometric structural parameters are as follows: Thickness gradient: The thickness at the root of the sheet is 0.3 mm to 0.6 mm, and the thickness at the end is 0.1 mm to 0.2 mm; Growth angle: The angle θ between the thin plate and the skeleton reference plane is 30 degrees to 60 degrees, and the tilting direction is opposite to the melt filling direction in step S4; Array spacing: The spacing D between adjacent thin plates is 1.0 mm to 2.0 mm, which is greater than the minimum flow layer thickness of the injection melt.

3. The additive hybrid manufacturing method for a new energy relay housing according to claim 2, characterized in that, The process parameters for interfacial surface modification in step S2 are characterized as follows: Plasma scanning: Atmospheric pressure low-temperature plasma beam is used, the scanning speed is set to 5 mm / s to 10 mm / s, and the distance between the nozzle and the skeleton surface is 10 mm to 15 mm; Coupling agent heat treatment: After spraying a 3% to 5% silane coupling agent solution, heat it in an environment of 80°C to 100°C for 10 to 15 minutes.

4. The additive hybrid manufacturing method for a new energy relay housing according to claim 3, characterized in that, The geometric features of the collapsible support element in step S3 are as follows: Cross-sectional shape: It has a hollow arch bridge-shaped or hemispherical thin-walled shell structure with a wall thickness of 0.2 mm to 0.3 mm; Interference fit amount: The height of the support unit in its free state exceeds the nominal size of the mold cavity by 0.05 mm to 0.15 mm; Positioning state: In the mold-closed state, the top of the support unit undergoes plastic collapse deformation, and the amount of deformation is equal to the interference fit amount.

5. The additive hybrid manufacturing method for a new energy relay housing according to claim 4, characterized in that, The specific process control parameters for the first stage in step S4 are as follows: Temperature field construction: The injection melt temperature is maintained at 250°C to 280°C, and the mold temperature is controlled at 60°C to 80°C to create a controlled transient temperature difference on the component surface; Laminar flow propulsion: The linear propulsion speed of the melt in the mold cavity is controlled to be 15 mm / s to 35 mm / s; Thermal softening window: The time span for the melt flow front to contact and cover the preset directional deformation component is controlled to be 0.5 seconds to 2.0 seconds, and this stage continues until the melt filling amount reaches 50% to 70% of the mold cavity volume, ensuring that the component material completes the phase transition from the glassy state to the high elastic state.

6. The additive hybrid manufacturing method for a new energy relay housing according to claim 1, characterized in that, The specific process control parameters for the second stage in step S4 are as follows: V / P switching and pressurization: When the melt filling amount reaches the set threshold, the linear propulsion speed of the melt is increased to 60mm / s to 100mm / s, and the injection pressure is stepped up to 60MPa to 90MPa; Compression deformation characteristics: Using the high pressure as a normal load, the component in a highly elastic state is pressed into the gap between the melt and the skeleton; Final geometric shaping: At the end of the pressure holding period, the angle between the component and the skeleton surface is compressed to 10 to 15 degrees, and the component exhibits an arc-shaped bending state with a bending radius R of 2.0 to 3.5 times its plate length L.

7. The additive hybrid manufacturing method for a new energy relay housing according to claim 1, characterized in that, Step S5, the pressure holding and cold-fixing locking, includes: Maintain a holding pressure of 60MPa to 90MPa for 3 to 8 seconds to compensate for cooling contraction; After the injection molding layer temperature drops below the glass transition temperature, the injection molding layer exhibits a volume shrinkage rate of 1.5% to 2.0%. The component recovers its stiffness and springs back as the temperature decreases, and its end is embedded in the shrinking inner wall of the injection-molded layer, forming a mechanical interference fit with an embedding depth of 0.05mm to 0.2mm.

8. The additive hybrid manufacturing method for a new energy relay housing according to claim 1, characterized in that, In step S1, the geometric structural features of the three-dimensional variable cross-section arc-extinguishing channel are as follows: Self-supporting cross-sectional profile: The cross-section of the flow channel is enclosed by a U-shaped or V-shaped base at the bottom and a self-supporting dome at the top. The angle α between the tangent of the inner wall of the dome and the horizontal construction plane satisfies 45°≤α≤90° throughout the entire length of the flow channel. Axial variable diameter structure: The flow channel is connected sequentially along the gas flow direction by a contraction section, a throat section, and an expansion section; the ratio of the cross-sectional area of ​​the throat section to the inlet cross-sectional area of ​​the contraction section is in the range of 0.4 to 0.6; Microstructure of the inner wall: The inner wall surface of the flow channel is integrally formed with discontinuous hemispherical or pyramidal micro-protrusions, the height of which is 5μm to 20μm and the spacing between adjacent micro-protrusions is 20μm to 50μm.

9. The additive hybrid manufacturing method for a new energy relay housing according to claim 1, characterized in that, The material parameters of the functional skeleton and the thermoplastic engineering plastic are as follows: Functional skeleton: Ceramic-filled photosensitive resin with a heat distortion temperature greater than 240℃ is selected; Thermoplastic engineering plastics: Glass fiber reinforced polybutylene terephthalate or nylon are selected; Thermal compatibility: Under the temperature and pressure conditions of the injection molding holding stage, the compression deformation of the functional skeleton body is less than 0.05 mm.

10. A new energy relay housing, prepared by the additive hybrid manufacturing method for a new energy relay housing according to any one of claims 1 to 9, characterized in that: It includes an internal functional framework and an external injection-molded layer; At the interface between the two, the thin plate structure on the surface of the functional skeleton is encapsulated in the injection molding layer in an arc-shaped bending state of R=(2.0~3.5)L, and the tip of the thin plate structure forms a mechanical undercut with the injection molding layer. The airtightness of the outer shell interface has a leakage rate of less than 10 Pa·cm³ / s under a pressure of 50 kPa.

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