An electromagnetic compatibility wire harness shield termination and manufacturing process

Abstract

The application relates to the technical field of electric connectors, and discloses an electromagnetic compatibility wire harness shielding end and a manufacturing process. The method comprises the following steps: layer-by-layer stripping and cutting of the end of a shielding cable to expose the conductor, the insulating layer and the braided layer in a stepped manner; folding the braided layer backward and covering the outer sheath surface; sleeving an inner conductive sleeve outside the folded braided layer; sleeving an outer compression sleeve outside the inner conductive sleeve and applying radial pressure, so that the inner conductive sleeve and the folded braided layer are jointly compressed on the outer sheath surface; loading the compressed cable end into a connector tail accessory, so that the outer compression sleeve and the inner wall of the connector tail accessory form annular contact; and butting and locking the connector tail accessory and the connector body. The process realizes large-area and low-impedance annular contact between the braided layer and the connector shell through a double-sleeve compression structure, and has the advantages of reliable connection, excellent electrical performance, simple operation and suitability for batch production.

Description

Technical Field

[0001] This invention relates to the field of electrical connector technology, specifically to an electromagnetic compatibility wire harness shielded terminal and its manufacturing process. Background Technology

[0002] With the increasing integration and rising operating frequencies of modern electronic devices, the internal electromagnetic environment is becoming increasingly complex. Cable harnesses, as crucial carriers of signal transmission, are susceptible to interference from external electromagnetic radiation during device interconnection, leading to signal distortion or errors. They may also propagate high-frequency noise through radiation, affecting the normal operation of other sensitive circuits or equipment. To improve the electromagnetic compatibility of electronic equipment, shielded cables with braided shielding are commonly used in engineering practice for signal transmission. Special shielded termination structures are installed at the connection points between the cable and connectors to ensure reliable grounding and electromagnetic sealing of the shielding layer, effectively suppressing electromagnetic interference coupling paths.

[0003] Currently, common methods for grounding the braided layer of shielded cables at connector tail accessories include: directly twisting the braided layer into a bundle and then welding or crimping it onto the inner wall of the connector tail accessory, or using metal clamps to tightly press the braided layer between the inner wall of the tail accessory and a matching clamping sleeve. However, these traditional methods have some shortcomings in practical operation. When using the method of twisting the braided layer into a bundle and then welding, the high temperature generated during the welding process can easily damage the insulation layer inside the conductor, and even change the crystallization state of the conductor material, affecting the electrical performance and mechanical strength of the cable. Moreover, the welding operation is highly dependent on the skill level of the operator, resulting in low production efficiency and difficulty in ensuring the consistency of the weld points. When using the clamping method, because the braided layer itself is a soft mesh structure, it is easy to generate wrinkles or local accumulation during the clamping process, leading to uneven contact between the braided layer and the clamping sleeve, resulting in high and unstable contact resistance. Especially in high-frequency signal transmission, due to the skin effect, the uneven contact interface will cause significant impedance discontinuity, thereby aggravating signal reflection and loss.

[0004] Furthermore, in existing shielding connector manufacturing processes, the braided layer, after folding, typically contacts the inner wall of the connector tail accessory directly. Since connector tail accessories are mostly made of metal, their inner wall surface has limited processing precision. Mechanical clamping alone cannot guarantee a sufficiently large and long-term stable actual contact area between the braided layer and the tail accessory. During long-term use, factors such as thermal expansion and contraction due to temperature cycles and mechanical vibration can cause the contact pressure at the clamping interface to loosen, increasing contact resistance and deteriorating the grounding conductivity of the shielding layer, thus reducing the electromagnetic shielding effect. Simultaneously, after folding, the edges of the braided layer are prone to developing scattered metal burrs. If not properly handled, these burrs may pierce the insulation layer or make unintended electrical contact with other live parts, posing a safety hazard. Summary of the Invention

[0005] The purpose of this invention is to provide an electromagnetic compatibility wire harness shielding terminal and its manufacturing process to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides an electromagnetic compatibility wire harness shielded terminal and its manufacturing process, the process comprising:

[0007] The ends of the shielded cable are stripped layer by layer, exposing the conductor, conductor insulation layer and braided shield layer in a stepped manner.

[0008] The exposed braided shielding layer is folded back axially and covered on the outer sheath surface of the shielded cable;

[0009] An inner conductive sleeve is fitted over the outside of the folded braided shielding layer, so that the inner wall of the inner conductive sleeve and the outer wall of the folded braided shielding layer form a first annular contact surface.

[0010] An outer compression sleeve is fitted over the inner conductive sleeve. By applying radial pressure to the outer compression sleeve, the outer compression sleeve presses the inner conductive sleeve and the folded braided shielding layer together against the outer sheath surface of the shielded cable.

[0011] Insert the compressed shielded cable end into the connector tail accessory, so that the outer wall of the outer compression sleeve and the inner wall of the connector tail accessory form a second annular contact surface;

[0012] Connect and lock the connector tail accessory to the connector body.

[0013] Furthermore, in the step of stripping the shielded cable layer by layer at its ends:

[0014] Using a circumferential cutter, the outer sheath is circumferentially cut at a first predetermined length from the end of the shielded cable. The circumferentially cut outer sheath section is then peeled off axially to expose the first exposed section of the braided shielding layer.

[0015] Using a circumferential cutter, the braided shielding layer is circumferentially cut at a second predetermined length from the end of the shielded cable. The circumferentially cut braided shielding layer is then peeled off axially to expose a first exposed section of the conductor insulation layer. The second predetermined length is greater than the first predetermined length.

[0016] Using a circumferential cutter, the conductor insulation layer is circumferentially cut at a third predetermined length from the end of the shielded cable. The circumferentially cut conductor insulation layer is then peeled off axially to expose the first exposed section of the conductor. The third predetermined length is greater than the second predetermined length.

[0017] Furthermore, in the step of folding the exposed braided shielding layer axially backward and covering the outer sheath surface of the shielded cable:

[0018] The first exposed section of the braided shielding layer is folded axially towards the root of the shielded cable, starting from the stripping position;

[0019] During the folding process, the braided structure of the braided shielding layer is kept intact, so that the folded braided shielding layer covers the outer sheath surface of the shielded cable in a double-layer structure;

[0020] The free end of the folded braided shielding layer extends to a third predetermined distance beyond the circumferential cut position of the outer sheath.

[0021] Furthermore, in the step of fitting an inner conductive sleeve over the folded braided shielding layer:

[0022] Select an inner conductive sleeve whose inner diameter matches the outer diameter of the folded braided shielding layer;

[0023] Insert the inner conductive sleeve from the end of the shielded cable and push it axially until the inner conductive sleeve completely covers the folded braided shielding layer.

[0024] The axial length of the inner conductive sleeve is greater than the axial length of the folded braided shielding layer, so that the two ends of the inner conductive sleeve exceed the two ends of the folded braided shielding layer by a fourth predetermined distance and a fifth predetermined distance, respectively.

[0025] Furthermore, in the step of fitting an outer compression sleeve over the inner conductive sleeve:

[0026] Select an outer compression sleeve with an inner diameter larger than the outer diameter of the inner conductive sleeve;

[0027] Insert the outer compression sleeve into the end of the shielded cable and push it axially until the outer compression sleeve and the inner conductive sleeve are aligned axially.

[0028] The axial length of the outer compression sleeve is equal to the axial length of the inner conductive sleeve.

[0029] Furthermore, in the step of applying radial pressure to the outer compression sleeve:

[0030] Place the end of the shielded cable, which is fitted with an outer compression sleeve, into the cavity of the crimping mold;

[0031] Drive the pressing die to close, so that the pressing surface of the pressing die applies uniform radial pressure along the circumference of the outer pressing sleeve;

[0032] Radial pressure causes plastic deformation of the outer clamping sleeve, reducing the inner diameter of the outer clamping sleeve to an interference fit with the outer diameter of the inner conductive sleeve.

[0033] During the plastic deformation process, the outer compression sleeve transmits radial pressure to the inner conductive sleeve, forming an airtight annular contact between the inner wall of the inner conductive sleeve and the outer wall of the folded braided shielding layer.

[0034] Furthermore, in the step of inserting the compressed shielded cable end into the connector tail accessory:

[0035] Select a connector tail accessory with an annular conductive protrusion on the inner wall;

[0036] Insert the compressed shielded cable end into the tail end of the connector accessory and push it forward axially;

[0037] During the pushing process, the outer wall of the outer clamping sleeve and the annular conductive boss on the inner wall of the connector tail accessory form a second annular contact surface;

[0038] Continue pushing the shielded cable end until the first exposed section of the conductor extends a sixth predetermined distance from the front end of the connector tail accessory.

[0039] Furthermore, in the step of mating and locking the connector tail accessory with the connector body:

[0040] Connect the front end of the connector tail accessory to the tail end of the connector body;

[0041] Rotate the connector tail accessory so that the external thread at the front end of the connector tail accessory engages with the internal thread at the tail end of the connector body;

[0042] Continue rotating the connector tail accessory to the predetermined torque value so that the front end face of the connector tail accessory fits against the tail end face of the connector body;

[0043] After the connector tail accessory is mated and locked with the connector body, the first exposed section of the conductor extends into the connector body and mates with the contact pair inside the connector body.

[0044] Furthermore, after the step of mating and locking the connector tail accessory with the connector body, the following steps are also included:

[0045] A heat-shrink tubing is fitted between the outer wall of the connector tail accessory and the outer sheath of the shielded cable;

[0046] Heat the heat shrink tubing to a predetermined temperature, causing it to shrink and tightly wrap around the joint between the outer wall of the connector tail accessory and the outer sheath of the shielded cable.

[0047] After the heat shrink tubing shrinks, the inner wall of the heat shrink tubing forms a sealed contact with the outer wall of the connector tail accessory and the surface of the outer sheath of the shielded cable.

[0048] The present invention also includes an electromagnetic compatibility wire harness shielding terminal, which is manufactured by the above-mentioned manufacturing process of an electromagnetic compatibility wire harness shielding terminal.

[0049] Compared with the prior art, the beneficial effects of the present invention are:

[0050] After the exposed braided shielding layer is folded back axially and covered on the outer sheath surface, the braided layer is stacked on the cable outer sheath in a double-layer structure. On the one hand, this increases the effective thickness and mechanical strength of the braided layer at this location, making it less likely to be crushed or broken during subsequent compression. On the other hand, the folded braided layer is evenly distributed along the outer sheath surface, eliminating the original curling stress and loose state of the braided layer, which is conducive to forming a uniform annular contact between the subsequent sleeve components and the braided layer. After the inner conductive sleeve is fitted over the folded braided layer, the inner wall of the inner conductive sleeve and the outer wall of the folded braided layer form the first annular contact surface. The area of ​​this contact surface is significantly increased compared to the traditional wire harness twisting grounding method, the contact resistance is significantly reduced, and the contact interface is uniform and continuous, which can effectively meet the requirements of low impedance grounding of the shielding layer during high-frequency signal transmission.

[0051] Furthermore, an outer compression sleeve is fitted externally, and radial pressure is applied to the outer compression sleeve, causing it to press the inner conductive sleeve and the folded braided layer together against the surface of the outer sheath. This structural design allows the braided layer to be sandwiched between the inner conductive sleeve and the outer sheath, while the inner conductive sleeve is also wrapped by the outer compression sleeve, forming a multi-layer composite compression structure. This structure has excellent resistance to mechanical vibration and impact. When subjected to temperature cycling, because both the inner conductive sleeve and the outer compression sleeve are made of metal, their coefficients of thermal expansion are close to those of the braided layer and the outer sheath. This ensures stable contact pressure between the layers, and the contact interface is less prone to loosening or fretting wear due to thermal mismatch, thus guaranteeing the long-term reliability of the shielding layer grounding path.

[0052] After the compressed shielded cable end is inserted into the connector tail accessory, the outer wall of the outer compression sleeve and the inner wall of the connector tail accessory form a second annular contact surface. At this point, the electrical conduction path of the shielding layer is as follows: the braided layer connects to the inner conductive sleeve through the first annular contact surface; the inner conductive sleeve and the outer compression sleeve achieve tight electrical contact through an interference fit; the outer compression sleeve then connects to the connector tail accessory through the second annular contact surface; and finally, the connector tail accessory and the connector body are mated and locked together to achieve connection with the equipment housing ground or reference ground. All contact interfaces in the entire electrical path are large-area annular surface contacts, and after radial compression, each contact surface has sufficient contact pressure and low contact resistance, which can meet the stringent requirements for shielding layer grounding impedance in electromagnetic compatibility design, effectively suppressing the conduction and radiation of electromagnetic interference.

[0053] After the connector tail accessory is mated and locked with the connector body, the entire shielded termination structure becomes a mechanically integrated unit. The axial and radial relative positions of all components are locked, preventing shielding layer detachment or poor contact due to cable bending or pulling. Compared to traditional welding or single-layer crimping methods, this process eliminates the need for high-temperature operation, avoiding the risk of heat damage. Furthermore, the sleeve components used are all standard parts, facilitating automated or semi-automated mass production. It offers good processing consistency, a simple and controllable operation process, and significantly improves production efficiency and product qualification rate. Attached Figure Description

[0054] Figure 1 This diagram illustrates the manufacturing process steps of an electromagnetic compatibility wire harness shielded terminal as described in this invention. Detailed Implementation

[0055] The technical solution of the present invention will be described in detail and completely below with reference to specific embodiments and comparative examples. The following embodiments are only used to illustrate the technical content of the present invention and are not intended to limit the scope of protection of the present invention. Based on the process principle of the present invention, all implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] The manufacturing process of the electromagnetic compatibility (EMC) wire harness shielded terminal disclosed in this invention is based on the core principle of using a stepped stripping method for the shielded cable end structure, double-layer braided shielding folding and wrapping, double-layer sleeve graded compression, annular surface conductive contact mating, and sealing reinforcement processes to achieve a fully fitted, highly conductive, and highly sealed EMC structure for the wire harness shielded terminal. This solves the technical defects of traditional wire harness shielded terminal heads, such as large contact gaps, discontinuous shielding, electromagnetic leakage, sealing failure, and loose connections. All embodiments and comparative examples of this invention use shielded cables of the same specifications, processing equipment, connector accessories, and testing equipment to ensure that the experimental variables are singular and the experimental data are comparable.

[0057] The basic parameters for this experiment are standardized as follows: the standard shielded cable used is AFRP-150 2.5mm² high-temperature shielded cable, the outer sheath is made of fluoroplastic, the conductor insulation is cross-linked polyethylene, the braided shielding layer is tin-plated copper braided mesh, and the braiding density is 95%. The processing equipment includes a fully automatic ring-cutting stripper, a precision hydraulic crimping die, a torque wrench, and a constant temperature heat shrink oven. The testing equipment includes a loop resistance tester, an electromagnetic shielding effectiveness tester, an airtightness tester, and a vibration durability test bench. The matching connector is an aviation waterproof connector, matched with a dedicated conductive tail accessory.

[0058] Example 1

[0059] See appendix Figure 1 This embodiment provides a manufacturing process for an electromagnetic compatibility wire harness shielded terminal, which specifically includes the following steps:

[0060] S1. Stepped Layer-by-Layer Stripping of Shielded Cable Ends: A fully automatic circumferential cutter is used to perform step-by-step circumferential stripping of the shielded cable ends. A first predetermined length of 8mm is set, and the outer sheath is circumferentially cut at a position 8mm from the cable end. The circumferential cutting depth is precisely controlled to the outer sheath wall thickness to avoid damaging the internal braided shielding layer. The 8mm long outer sheath section is peeled off axially, exposing the first exposed section of the braided shielding layer. A second predetermined length of 14mm is set, and the braided shielding layer is circumferentially cut at a position 14mm from the cable end. This section of the braided shielding layer is peeled off, exposing the first exposed section of the conductor insulation layer. A third predetermined length of 20mm is set, and the conductor insulation layer is circumferentially cut at a position 20mm from the cable end. The corresponding insulation layer section is peeled off, exposing the first exposed section of the conductor. This completes the stepped layered exposure structure, ensuring that the conductor, conductor insulation layer, and braided shielding layer are distributed in a stepped manner with progressively expanding outwards, without any burrs or structural damage.

[0061] S2, Axial Folding and Covering of Braided Shielding Layer: The first exposed section of the 6mm long braided shielding layer exposed in step S1 is folded at a uniform speed from the stripping root position along the cable axis towards the cable root. During the folding process, the braided structure of the tinned copper braided mesh is kept intact, without broken wires, looseness, or twisting deformation, so that the braided shielding layer forms a double-layer covering structure that tightly covers the surface of the cable outer sheath. The free end of the folded braided shielding layer extends to 3mm outside the circumferential cut position of the outer sheath, ensuring that the folded covering area completely covers the subsequent sleeve crimping range.

[0062] S3. Install the inner conductive sleeve: Select a copper inner conductive sleeve with an interference fit between its inner diameter and the outer diameter of the folded double-layer braided shielding layer. The axial length of the inner conductive sleeve is 12mm. Insert the inner conductive sleeve axially from the cable end, pushing it at a uniform speed until the sleeve completely covers the folded braided shielding layer. One end of the sleeve should extend 2mm beyond the end of the braided shielding layer, and the other end should extend 4mm beyond the root of the braided shielding layer, ensuring that the entire braided shielding layer is completely covered by the inner conductive sleeve without any exposed areas.

[0063] S4. Install and radially tighten the outer layer compression sleeve: Select a stainless steel outer layer compression sleeve with an axial length of 12mm, which is exactly the same length as the inner conductive sleeve. The initial inner diameter is 0.8mm larger than the outer diameter of the inner conductive sleeve. Slide the outer layer compression sleeve onto the cable end, ensuring precise axial alignment so that the inner and outer sleeves are completely aligned axially and without circumferential offset. Place the assembled cable end into the standard cavity of the crimping mold. After closing the mold, apply uniform radial pressure through the hydraulic system. The crimping pressure is set to 8MPa, and the holding time is 5s. This causes the outer layer compression sleeve to undergo uniform plastic deformation, shrinking its inner diameter to fit tightly against the outer diameter of the inner conductive sleeve. The radial pressure is fully transferred to the inner conductive sleeve, creating a fully circumferential, airtight annular contact between the inner wall of the inner conductive sleeve and the outer wall of the double-layer braided shielding layer, without gaps, loose connections, or localized crushing damage.

[0064] S5. Assemble the connector tail accessory: Select a matching connector tail accessory with an annular conductive boss on the inner wall. Insert the clamped cable end into the tail accessory and push it axially at a uniform speed. During the pushing process, ensure that the outer wall of the outer clamping sleeve and the annular conductive boss on the inner wall of the tail accessory are precisely fitted to form a second annular conductive contact surface. Continue to push the cable end so that the first exposed section of the conductor extends 4mm from the front end of the tail accessory, ensuring that the conductor can be smoothly connected to the connector body.

[0065] S6. Connector mating and locking: Precisely align the front end of the connector tail accessory with the tail end of the connector body. Rotate the tail accessory at a constant speed using a torque wrench to ensure that the external thread of the tail accessory front end smoothly engages with the internal thread of the connector body. Continue tightening to the preset torque of 1.2 N·m. At this point, the front end face of the tail accessory and the tail end face of the connector body are completely and tightly fitted without any gaps. After mating, the exposed conductor at the cable end is fully inserted into the connector body and precisely mats with the internal contact pair, ensuring a complete conductive structure.

[0066] S7. Sealing and Reinforcement Treatment: A polyolefin heat shrink tubing is fitted at the joint between the outer wall of the connector tail accessory and the outer sheath of the cable. The initial inner diameter of the heat shrink tubing is adapted to the overall outer diameter after assembly. The assembled wire harness end is placed in a constant temperature heat shrink oven, and the heating temperature is set to 125℃. The heat shrink tubing is heated at a constant temperature for 2 minutes to make the heat shrink tubing shrink evenly and tightly wrap around the joint between the outer wall of the tail accessory and the outer sheath of the cable. After cooling, the inner wall of the heat shrink tubing and the contact surface form a completely sealed structure, isolating external moisture and dust, and achieving end sealing protection.

[0067] Example 2

[0068] This embodiment provides a manufacturing process for an electromagnetic compatibility wire harness shielded terminal. The overall process steps are basically the same as in Embodiment 1, with the difference being the adjustment of process parameters, sleeve specifications, and crimping parameters for each step. The specific key step parameters are as follows:

[0069] S1. Stepped stripping of shielded cable ends: Set a first predetermined length of 10mm, circumferentially cut and strip 10mm of the outer sheath to expose the braided shielding layer; set a second predetermined length of 16mm, circumferentially cut and strip 6mm of the braided shielding layer; set a third predetermined length of 22mm, circumferentially cut and strip 6mm of the conductor insulation layer to expose the conductor exposed section, ensuring that the stepped stripping structure is flat and undamaged.

[0070] S2. Axial folding and wrapping of the braided shielding layer: After folding the braided shielding layer, wrap it in two layers on the surface of the outer sheath, with the free end extending 4mm outside the circumferential cut position of the outer sheath, keeping the braided structure intact and undamaged throughout the process.

[0071] S3. Install inner conductive sleeve: Select phosphor bronze inner conductive sleeve with an axial length of 14mm. The two ends of the sleeve extend 3mm and 5mm beyond the folded braided shielding layer, respectively, to completely cover the shielding layer structure.

[0072] S4. Install the outer layer compression sleeve and radially compress it: The axial length of the outer layer compression sleeve is 14mm, which is the same as the inner layer sleeve. The initial inner diameter is 1.0mm larger than the outer diameter of the inner layer sleeve. The mold closing pressure of the pressing mold is 9MPa, and the holding time is 6s, so that the outer layer sleeve undergoes uniform plastic deformation, and the airtight and tight pressing of the double-layer sleeve and the braided shielding layer is achieved.

[0073] S5. Assemble the connector tail accessory: The first exposed section of the conductor extends 5mm from the front end of the tail accessory to ensure sufficient mating stroke.

[0074] S6. Connector mating and locking: The mating and locking torque is set to 1.4 N·m to ensure tight thread engagement and no loosening gaps.

[0075] S7. Sealing and reinforcement treatment: Heat shrink tubing is heated to 130℃ and kept at a constant temperature for 2.5 minutes to complete the sealing and wrapping.

[0076] Example 3

[0077] This embodiment provides a manufacturing process for an electromagnetic compatibility (EMC) wire harness shielded terminal. The overall process steps are basically the same as in Embodiment 1, but low-temperature adaptation process parameters are used to adapt the wire harness for use in low-temperature conditions. The specific key steps and parameters are as follows:

[0078] S1. Stepped stripping of shielded cable ends: first predetermined length 6mm, second predetermined length 12mm, third predetermined length 18mm, step-by-step stripping to form a stepped structure, with smooth and burr-free stripping cuts.

[0079] S2. Axial folding and wrapping of the braided shielding layer: After the braided shielding layer is folded, the free end extends 2mm beyond the circumferential cut position of the outer sheath, and the double-layer wrapping structure is flat and wrinkle-free.

[0080] S3. Install inner conductive sleeve: inner conductive sleeve made of copper, axial length 10mm, with both ends extending 1mm and 3mm beyond the shielding layer respectively.

[0081] S4. Install the outer compression sleeve and radially compress it: the axial length of the outer sleeve is 10mm, and the initial inner diameter is 0.6mm larger than that of the inner sleeve; the compression pressure is 7MPa, the pressure holding time is 4s, and the low-pressure slow compression is used to avoid stress concentration cracking of the sleeve under low temperature conditions.

[0082] S5. Assemble connector tail accessory: Conductor extension length 3mm, suitable for miniaturized connector mating structure.

[0083] S6. Connector mating and locking: Locking torque 1.0 N·m to avoid excessive torque causing low-temperature thread breakage.

[0084] S7. Sealing and reinforcement treatment: Low-temperature special heat shrink tubing, heating temperature 120℃, constant temperature heating for 1.5min, rapid forming of sealing structure.

[0085] Example 4

[0086] This embodiment provides a manufacturing process for an electromagnetic compatibility (EMC) wire harness shielded terminal. The overall process steps are basically the same as in Embodiment 1, but high-strength vibration-resistant process parameters are used to adapt to vehicle-mounted and airborne vibration conditions. The specific key steps and parameters are as follows:

[0087] S1. Stepped stripping of shielded cable ends: first predetermined length 9mm, second predetermined length 15mm, third predetermined length 21mm, precise graded stripping to ensure structural dimensional stability.

[0088] S2. Axial folding and wrapping of the braided shielding layer: After folding, the free end extends 3.5mm beyond the circumferential cut position of the outer sheath, and the double-layer wrapping is neither loose nor offset.

[0089] S3. Inner conductive sleeve: Silver-plated copper inner conductive sleeve, axial length 13mm, with both ends extending 2.5mm and 4.5mm beyond the shielding layer respectively, to improve conductivity and oxidation resistance.

[0090] S4. Install the outer compression sleeve and radially compress it: The outer sleeve is made of high-strength alloy steel with an axial length of 13mm and an initial inner diameter that is 0.9mm larger than that of the inner sleeve; the compression pressure is 10MPa and the pressure holding time is 7s, which strengthens the compression fastness and improves the vibration resistance.

[0091] S5. Assemble connector tail accessories: Conductor extension length 4.5mm to ensure mating stability.

[0092] S6 Connector mating and locking: Locking torque 1.5 N·m, strengthening the thread locking strength, suitable for high-frequency vibration conditions.

[0093] S7. Sealing and reinforcement treatment: Thickened heat shrink tubing, heating temperature 135℃, constant temperature heating for 3 minutes, to improve the thickness of the sealing layer and its wear and vibration resistance.

[0094] Comparative Example 1

[0095] This comparative example uses a traditional wire harness shielding termination manufacturing process, and is compared with Embodiment 1 of the present invention. The specific steps are as follows:

[0096] T1. Cable end stripping: The shielded cable end is stripped using a one-time flat cutting method, directly removing the outer sheath, braided shielding layer and insulation layer for 18mm length at the end, so that the conductor, shielding layer and insulation layer ends are flush, without a stepped layered structure.

[0097] T2. Shielding layer treatment: The flat and exposed braided shielding layer is folded outwards directly into a single-layer covering structure. Excess shielding layer is trimmed. There is no double-layer covering or precise positioning extension structure.

[0098] T3. Sleeve assembly: A single-layer compression sleeve is installed outside the shielding layer, without an inner conductive sleeve transition structure. The shielding layer and the cable outer sheath are directly pressed together through the single-layer sleeve.

[0099] T4. Press forming: The pressing sleeve is pressed by a single point stamping method. There is no uniform pressure in the circumference, resulting in local deformation and local loose connection of the sleeve.

[0100] T5. Connector assembly: The crimped cable end is directly inserted into the connector tail accessory. There is no precise matching of the annular conductive contact surface. The connection is made by simple contact through the outer wall of the sleeve.

[0101] T6. Mating and locking: Conventional torque locking connector, without precise torque control and without subsequent heat shrink sealing reinforcement process.

[0102] Comparative Example 2

[0103] This comparative example is based on the basic process of the present invention, but omits the double-layer folded structure of the braided shielding layer. The remaining steps are completely consistent with those of Example 1. The specific steps are as follows:

[0104] T1. Using the same step-by-step stripping parameters as in Example 1, the cable end is stripped stepwise.

[0105] T2. Shielding layer treatment: The exposed woven shielding layer is directly turned outward and laid flat, and the excess shielding layer is cut off, leaving only a single-layer shielding covering structure, without forming a double-layer superimposed covering structure.

[0106] T3-T7 are processed sequentially according to the sleeve assembly, pressing and forming, connector assembly, mating and locking, and heat shrink sealing processes of Example 1. The process parameters, equipment, and accessories are consistent with those of Example 1, except that the shielding layer covering structure is different.

[0107] Comparative Example 3

[0108] This comparative example is based on the basic process of the present invention, but omits the heat shrink tubing sealing and reinforcement step. The remaining steps are completely consistent with those of Example 1. The specific steps are as follows:

[0109] T1-T6 completely replicate all processes and parameters of Example 1, including stepped peeling, shielding layer folding, sleeve assembly, radial pressing, connector assembly, and mating locking, to ensure that the front-end processing structure is completely consistent.

[0110] T7. The heat shrink tubing installation and heat sealing steps are eliminated. The joint between the connector tail accessory and the cable outer sheath is an exposed open structure without a sealing and protective layer.

[0111] Experimental testing and data comparison analysis

[0112] To verify the superiority of the processes in each embodiment of the present invention, uniform performance testing was conducted on the finished wire harness shielding terminals prepared in 4 sets of embodiments and 3 sets of comparative examples. The test indicators included contact circuit resistance, electromagnetic shielding effectiveness, airtightness, vibration durability failure rate, and waterproof and dustproof rating. All tests followed the electromagnetic compatibility test standards of GB / T 18386-2021 and GJB 151B-2013 for wire harnesses. Ten sets of tests were conducted on each sample, and the average value was taken as the final test data. The specific test results and analysis are as follows.

[0113] Table 1: Electrical and shielding performance test data for each embodiment and comparative example

[0114]

[0115] Contact loop resistance is a core indicator for evaluating the conductive contact performance of wire harness shielding terminations. Lower resistance values ​​indicate better contact conductivity and lower electromagnetic losses. The contact loop resistances of the four embodiments of this invention are all consistently within the range of 1.86 mΩ to 2.31 mΩ, exhibiting extremely low overall values ​​and minimal fluctuation. Embodiment 4, employing a silver-plated copper inner sleeve and a high-pressure pressing process, exhibits the best conductivity, with a resistance of only 1.86 mΩ. Embodiment 3 uses a low-temperature adaptation process with relatively conservative parameters, resulting in a slightly higher resistance, but still significantly lower than the comparative standard. Comparative Example 1, using a traditional process lacking a stepped structure, double-layer sleeve pressing, and a large contact gap, has a loop resistance as high as 5.68 mΩ, more than 2.5 times the average value of the embodiments. Comparative Example 2, by eliminating the double-layer shielding folding structure, suffers from insufficient single-layer shielding contact area and poor adhesion, resulting in a resistance of 3.95 mΩ and a significant decrease in conductivity. Comparative Example 3 only omits the sealing process, without altering the conductive contact structure; therefore, its resistance value is essentially the same as that of Embodiment 1, proving that the sealing process does not affect conductivity.

[0116] Electromagnetic shielding effectiveness directly determines the electromagnetic interference resistance of the wiring harness. Under 1GHz high-frequency conditions, the higher the value, the better the shielding effect. The shielding effectiveness of all four examples is higher than 67dB, with Example 4 achieving the best at 71.3dB, which can fully meet the high electromagnetic compatibility requirements of automotive, industrial control, and aviation scenarios. Comparative Example 1 shows that the traditional shielding structure is discontinuous and has serious gap leakage, with a shielding effectiveness of only 52.4dB, highlighting the high-frequency electromagnetic leakage problem. Comparative Example 2 shows that the single-layer shielding structure has insufficient shielding layer coverage, reducing the shielding effectiveness to 60.8dB, a decrease of 7.7dB compared to Example 1, fully demonstrating the effect of the double-layer shielding folding structure on improving shielding performance. Comparative Example 3 shows that the shielding structure is complete, only lacking external sealing, and the shielding effectiveness is basically the same as the examples, indicating that the sealing structure does not directly affect the electromagnetic shielding performance.

[0117] The airtightness leakage rate reflects the tightness of the shielding termination structure. The lower the leakage rate, the fewer gaps and openings in the structure, and the better the shielding integrity. The leakage rates of the example group were all below 1 Pa / min, indicating excellent structural airtightness and no electromagnetic leakage gaps. Comparative Examples 1 and 2 showed significantly higher leakage rates due to loose pressing and poor shielding layer adhesion. Comparative Example 3 showed a significantly higher airtightness leakage rate due to the lack of heat-shrink sealing and gaps at the external interface, proving that the heat-shrink sealing process of this invention can effectively seal end gaps and improve the overall structural airtightness. At the same time, the example group achieved seamless conductive contact, while traditional processes and single-layer shielding processes had contact defects, fully verifying the rationality of the stepped peeling, double-layer wrapping, and double-layer sleeve uniform pressing process of this invention.

[0118] Table 2: Environmental durability test data for each embodiment and comparative example

[0119]

[0120] Vibration durability testing employed alternating vibration at frequencies ranging from 10Hz to 1000Hz. After 24 hours of continuous testing, the failure rate of the samples was statistically analyzed. A higher failure rate indicated poorer vibration resistance and resistance to loosening. All four sets of samples from the embodiments of this invention exhibited a 0% failure rate after high-intensity vibration testing, with no issues such as loose contact, sleeve misalignment, shielding layer detachment, or connector loosening, demonstrating extremely strong structural stability. Example 4, with optimized parameters for vibration conditions, showed a resistance change rate of only 2.1% after high and low temperature cycling, exhibiting optimal temperature resistance. Comparative Example 1, with its traditional process structure lacking precise clamping and sealing reinforcement, was prone to contact defects and sleeve displacement after vibration, resulting in a failure rate as high as 18.6%, making it completely unsuitable for vibration conditions. Comparative Example 2, with its single-layer shielding structure, suffered from insufficient contact stability, leading to localized contact failure after vibration, with a failure rate of 7.2%. Comparative Example 3, lacking heat-shrink sealing, was susceptible to vibration-induced micro-gaps at the end connections, resulting in a failure rate of 4.8%, significantly inferior to the embodiment groups in terms of durability.

[0121] The high and low temperature cycling test used alternating hot and cold cycles from -40℃ to 125℃. After 50 cycles, the change rate of circuit resistance was measured. The lower the change rate, the better the temperature resistance and conductivity stability of the structure. The resistance change rate of the example group was less than 3.5%, showing extremely strong temperature adaptability and maintaining stable conductivity and shielding performance under both high and low temperature environments. Comparative Example 1 had a large structural gap and no interference fit, resulting in a significant change in contact state after temperature deformation, with a resistance change rate of 12.8%. The change rates of Comparative Examples 2 and 3 were 8.5% and 4.1% respectively, both higher than those of the present invention. This proves that the double-layer sleeve interference fit and double-layer shielding structure of the present invention can effectively offset the structural gap changes caused by temperature deformation and ensure performance stability under extreme temperatures.

[0122] The waterproof and dustproof rating test results show that, after heat shrink sealing reinforcement, the overall protection level of the embodiment of the present invention reaches IP68, which can achieve complete dustproof and deep water immersion protection, and is suitable for outdoor, vehicle-mounted, and humid harsh working conditions. Comparative Examples 1 and 3 have no effective sealing structure, with a waterproof rating of only IP54 and a dustproof rating of IP5X, which cannot resist the intrusion of dust and moisture; although Comparative Example 2 has an optimized shielding structure, it has no sealing reinforcement, and its protective performance is still far lower than that of the process of the present invention, which fully verifies the key role of the heat shrink sealing process of the present invention in improving the environmental adaptability of the wire harness termination.

[0123] Table 3: Comparison of Different Process Structure Parameters and Technical Advantages

[0124]

[0125] A comparison of the structural systems clearly shows that the process of this invention integrates five core structures: stepped peeling, double-layer shielding, double-layer sleeve graded compression, double-ring surface conductive contact, and heat-shrinkable full sealing, forming a complete integrated shielding termination molding system. The stepped layered peeling structure provides a regular structural foundation for double-layer shielding and precise sleeve assembly, avoiding the structural chaos and contact misalignment problems caused by traditional flush peeling; the double-layer shielding superimposed wrapping structure significantly increases the contact area and structural thickness of the shielding layer, completely solving the defects of insufficient contact, easy loosening, and discontinuous shielding in single-layer shielding; the inner and outer double-layer sleeve structure realizes the graded function of "conductive bonding + tight compression", with the inner sleeve ensuring the airtightness of conductive contact and the outer sleeve providing plastic compression and fastening force, which, compared with the traditional single-layer sleeve, takes into account both conductivity and structural stability.

[0126] The circumferential uniform radial pressing process ensures uniform plastic deformation of the sleeve, eliminating local stress concentration and guaranteeing airtight contact throughout the circumference. This eliminates the problems of unstable resistance and electromagnetic gap leakage caused by point-line contact. The double-ring contact surface design achieves dual conductive conduction between the shielding layer and the sleeve, and between the sleeve and the connector, forming a closed-loop shielded conductive path with excellent shielding continuity. The heat-shrinkable sealing structure at the end seals all interface gaps, achieving multiple protections including structural sealing, dustproofing, waterproofing, and oxidation prevention.

[0127] Each comparative example exhibits core structural defects: Comparative Example 1, using traditional processes, suffers from structural shortcomings throughout the entire process of stripping, wrapping, crimping, and sealing, resulting in the worst performance; Comparative Example 2 lacks a double-layer shielding core structure, leading to insufficient shielding integrity and contact stability; Comparative Example 3 lacks a sealed protective structure, resulting in poor environmental adaptability. This invention, through multi-structure collaborative optimization, completely solves the industry pain points of unstable conduction, poor shielding effect, weak durability, and low environmental adaptability in traditional wire harness shielding terminations. It can be widely applied in fields with stringent requirements for electromagnetic compatibility and structural reliability, such as aviation, aerospace, automotive, industrial control, and new energy.

[0128] Based on the above three sets of test data tables and corresponding analysis, it can be seen that the electromagnetic compatibility harness shielding terminator prepared by this invention, through optimized stepped stripping parameters, double-layer shielding folding and covering structure, double-layer sleeve uniform pressing process, precise torque locking, and heat-shrink sealing reinforcement process, possesses extremely low contact resistance, ultra-high electromagnetic shielding efficiency, excellent airtight structure, zero vibration failure rate, and high-level waterproof and dustproof performance. The four differentiated embodiments can be adapted to conventional working conditions, high-precision working conditions, low-temperature working conditions, and high-frequency vibration working conditions, respectively, demonstrating wide process adaptability and strong parameter adjustability. Compared with traditional processes and single-structure improvement processes, the product prepared by the process of this invention exhibits significantly improved performance, with overwhelming advantages in structural stability, electromagnetic compatibility, and environmental durability, effectively solving the technical defects of existing shielding terminators such as poor contact, electromagnetic leakage, structural loosening, sealing failure, and poor durability.

[0129] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A manufacturing process for an electromagnetic compatibility wire harness shielded terminal, characterized in that, Includes the following steps: The ends of the shielded cable are stripped layer by layer, exposing the conductor, conductor insulation layer and braided shield layer in a stepped manner. The exposed braided shielding layer is folded back axially and covered on the outer sheath surface of the shielded cable; An inner conductive sleeve is fitted over the outside of the folded braided shielding layer, so that the inner wall of the inner conductive sleeve and the outer wall of the folded braided shielding layer form a first annular contact surface. An outer compression sleeve is fitted over the inner conductive sleeve. By applying radial pressure to the outer compression sleeve, the outer compression sleeve presses the inner conductive sleeve and the folded braided shielding layer together against the outer sheath surface of the shielded cable. Insert the compressed shielded cable end into the connector tail accessory, so that the outer wall of the outer compression sleeve and the inner wall of the connector tail accessory form a second annular contact surface; Connect and lock the connector tail accessory to the connector body.

2. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 1, characterized in that, In the step of stripping the shielded cable layer by layer from its ends: Using a circumferential cutter, the outer sheath is circumferentially cut at a first predetermined length from the end of the shielded cable. The circumferentially cut outer sheath section is then peeled off axially to expose the first exposed section of the braided shielding layer. Using a circumferential cutter, the braided shielding layer is circumferentially cut at a second predetermined length from the end of the shielded cable. The circumferentially cut braided shielding layer is then peeled off axially to expose a first exposed section of the conductor insulation layer. The second predetermined length is greater than the first predetermined length. Using a circumferential cutter, the conductor insulation layer is circumferentially cut at a third predetermined length from the end of the shielded cable. The circumferentially cut conductor insulation layer is then peeled off axially to expose the first exposed section of the conductor. The third predetermined length is greater than the second predetermined length.

3. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 2, characterized in that, In the step of folding the exposed braided shielding layer axially backward and covering the outer sheath surface of the shielded cable: The first exposed section of the braided shielding layer is folded axially towards the root of the shielded cable, starting from the stripping position; During the folding process, the braided structure of the braided shielding layer is kept intact, so that the folded braided shielding layer covers the outer sheath surface of the shielded cable in a double-layer structure; The free end of the folded braided shielding layer extends to a third predetermined distance beyond the circumferential cut position of the outer sheath.

4. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 3, characterized in that, In the step of fitting an inner conductive sleeve over the folded braided shielding layer: Select an inner conductive sleeve whose inner diameter matches the outer diameter of the folded braided shielding layer; Insert the inner conductive sleeve from the end of the shielded cable and push it axially until the inner conductive sleeve completely covers the folded braided shielding layer. The axial length of the inner conductive sleeve is greater than the axial length of the folded braided shielding layer, so that the two ends of the inner conductive sleeve exceed the two ends of the folded braided shielding layer by a fourth predetermined distance and a fifth predetermined distance, respectively.

5. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 4, characterized in that, In the step of fitting an outer compression sleeve over the inner conductive sleeve: Select an outer compression sleeve with an inner diameter larger than the outer diameter of the inner conductive sleeve; Insert the outer compression sleeve into the end of the shielded cable and push it axially until the outer compression sleeve and the inner conductive sleeve are aligned axially. The axial length of the outer compression sleeve is equal to the axial length of the inner conductive sleeve.

6. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 5, characterized in that, In the step of applying radial pressure to the outer compression sleeve: Place the end of the shielded cable, which is fitted with an outer compression sleeve, into the cavity of the crimping mold; Drive the pressing die to close, so that the pressing surface of the pressing die applies uniform radial pressure along the circumference of the outer pressing sleeve; Radial pressure causes plastic deformation of the outer clamping sleeve, reducing the inner diameter of the outer clamping sleeve to an interference fit with the outer diameter of the inner conductive sleeve. During the plastic deformation process, the outer compression sleeve transmits radial pressure to the inner conductive sleeve, forming an airtight annular contact between the inner wall of the inner conductive sleeve and the outer wall of the folded braided shielding layer.

7. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 6, characterized in that, In the step of inserting the compressed shielded cable end into the connector tail accessory: Select a connector tail accessory with an annular conductive protrusion on the inner wall; Insert the compressed shielded cable end into the tail end of the connector accessory and push it forward axially; During the pushing process, the outer wall of the outer clamping sleeve and the annular conductive boss on the inner wall of the connector tail accessory form a second annular contact surface; Continue pushing the shielded cable end until the first exposed section of the conductor extends a sixth predetermined distance from the front end of the connector tail accessory.

8. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 7, characterized in that, In the step of mating and locking the connector tail accessory with the connector body: Connect the front end of the connector tail accessory to the tail end of the connector body; Rotate the connector tail accessory so that the external thread at the front end of the connector tail accessory engages with the internal thread at the tail end of the connector body; Continue rotating the connector tail accessory to the predetermined torque value so that the front end face of the connector tail accessory fits against the tail end face of the connector body; After the connector tail accessory is mated and locked with the connector body, the first exposed section of the conductor extends into the connector body and mates with the contact pair inside the connector body.

9. The manufacturing process of an electromagnetic compatibility wire harness shielded terminal according to claim 8, characterized in that, After the step of mating and locking the connector tail accessory with the connector body, the following steps are also included: A heat-shrink tubing is fitted between the outer wall of the connector tail accessory and the outer sheath of the shielded cable; Heat the heat shrink tubing to a predetermined temperature, causing it to shrink and tightly wrap around the joint between the outer wall of the connector tail accessory and the outer sheath of the shielded cable. After the heat shrink tubing shrinks, the inner wall of the heat shrink tubing forms a sealed contact with the outer wall of the connector tail accessory and the surface of the outer sheath of the shielded cable.

10. An electromagnetic compatibility wire harness shielded terminal, characterized in that, It is manufactured using the manufacturing process of an electromagnetic compatibility wire harness shielded terminal as described in any one of claims 1-9.

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