Automobile wire harness production and processing method

Abstract

The invention discloses an automobile wire harness production and processing method, which relates to the technical field of automobile wire harness manufacturing, and comprises the following steps: smelting aluminum, iron, magnesium, copper and rare earth elements according to a specific proportion, refining and removing impurities through a three-stage temperature control process, preparing a strip through thin-strip continuous casting, and combining multi-pass cold rolling and two-stage aging treatment to form a high-strength wire. According to the method, the weight and cost of the wire harness are remarkably reduced, and meanwhile corrosion resistance, mechanical strength and high-frequency signal transmission stability are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile wiring harness manufacturing, and more particularly to a production and processing method of an automobile wiring harness. Background Art

[0002] At present, pure copper or copper alloy materials are commonly used in automobile wiring harnesses, which are heavy (density 8.96g / cm 3 ), insufficient corrosion resistance, and high-frequency signal transmission is susceptible to interference. Existing improvement solutions, such as aluminum conductors, reduce weight but have poor adaptability to the crimping process; and coated copper wires are prone to coating cracking in high-vibration environments.

[0003] Therefore, it is necessary to propose a production and processing method for automobile wiring harnesses to solve the above problems. Summary of the Invention

[0004] The purpose of the present invention is to solve the problems raised in the background technology.

[0005] In order to achieve the above-mentioned purpose, the present invention specifically adopts the following technical solutions:

[0006] A method for producing and processing an automobile wiring harness comprises the following steps:

[0007] (a) Alloy wire preparation: Al 92-95%, Fe 2.5-3.8%, Mg 1.2-1.8%, Cu 0.5-1.0%, RE 0.05-0.15% are mixed by mass, and then the wire is produced by strip casting, cold rolling, and aging treatment.

[0008] (b) Composite coating: First, chemical nickel plating is performed to form a 2 μm inner layer, and then graphene-modified resin is coated to form a 3 μm outer layer.

[0009] Furthermore, in the step (a):

[0010] Melting adopts three-stage temperature control:

[0011] First-level temperature control, temperature controlled at 750℃ for slag removal;

[0012] Secondary temperature control, temperature controlled at 720℃, adding Mg / Cu;

[0013] Three-stage temperature control, temperature controlled at 690℃ with RE degassing;

[0014] The temperature difference of each level is controlled within the range of ±30℃.

[0015] Furthermore, the thin strip continuous casting cooling rate is 1000-1200K / s, and the strip thickness is 2.0±0.2mm.

[0016] Furthermore, the cold rolling and aging process in step (a) is:

[0017] Initial rolling stage: The continuous casting strip is cold rolled four times, and the total deformation is controlled at 83%-87%.

[0018] Intermediate annealing: Flash annealing is performed after each rolling pass, with an annealing temperature of 425℃-435℃ and a holding time of 2.5-3.5min;

[0019] Secondary rolling: rolling the strip to a thickness of 0.58-0.62mm, with a single deformation of 48%-52%;

[0020] Final rolling after annealing: After annealing, the steel is rolled to the target thickness of 0.28-0.32mm, with a cumulative total deformation of 83%-87%;

[0021] Solution treatment: quenching in water at 510℃±5℃, transfer time ≤15s;

[0022] Two-stage aging: first-stage aging at 118℃-122℃ for 7.5-8.5h, second-stage aging at 168℃-172℃ for 1.8-2.2h.

[0023] Furthermore, the chemical plating solution in step (b) comprises the following components: 25±2 g / L nickel sulfate, 30±3 g / L sodium hypophosphite, and 10±1 g / L lactic acid, and the plating is performed at 85±2° C. for 20 min.

[0024] Furthermore, the outer resin coating in step (b) is graphene-modified polysiloxane, with a graphene content of 0.4-0.6wt%, carboxyl modification, a particle size of 1-5μm, and a withstand voltage of ≥5kV after curing at 180°C.

[0025] Furthermore, the continuously cast strip is rolled to a target wire diameter by a four-roll cold rolling mill, and the roll gap pressure fluctuation is ≤±0.05mm.

[0026] Furthermore, online quality monitoring is also provided: an electrochemical impedance spectrometer is installed after the coating process, and an automatic alarm and shutdown will be triggered if the impedance fluctuation exceeds ±5%.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. This invention significantly reduces the weight of the wiring harness by replacing traditional copper materials with high-strength aluminum alloys. The optimized alloy formula and stepped heat treatment process significantly improve the tensile strength and ductility of the wires.

[0029] 2. The nickel-based-graphene composite coating of the present invention synergistically enhances corrosion resistance and extends the service life of the wiring harness. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0031] 1. A method for producing and processing an automobile wiring harness.

[0032] 1. Material formulation implementation, high-voltage battery pack main wiring harness wires.

[0033] (1) Raw material ratio: 99.99% high-purity aluminum ingots according to GB / T 1196-2017 standard are selected as the base material, and 3.2% electrolytic iron is added according to weight percentage, wherein the Fe content is ≥99.8%, 1.5% magnesium ingot is added, wherein the Mg content is ≥99.9%, 0.8% oxygen-free copper, Cu-0F grade, and 0.1% cerium-lanthanum mixed rare earth, Ce:La=7:3.

[0034] (2) Pretreatment of ingredients: Aluminum ingots were cut into 50×50×100 mm blocks and preheated to 200°C to remove the surface oxide film; iron and copper metals were ball-milled into 80-120 mesh powders to reduce element segregation during smelting; rare earth coating agents were mixed in a ratio of KCl:Na2SiF6=6:4, dried at 200°C, and then sealed and stored.

[0035] 2. Step-by-step smelting process and smelting process parameter control.

[0036] (1) Primary deslagging stage: The aluminum substrate was placed in a graphite crucible, heated to 750±5°C, and 99.999% pure argon gas was introduced at a flow rate of 15 L / min. At the same time, hexachloroethane (C2Cl6) at a concentration of 0.5% by weight of the aluminum ingot was added as a refining agent, and deslagging was continued for 20 minutes.

[0037] (2) Element addition stage: Cool down to 720±3℃, add Fe, Mg, and Cu powders in sequence, start the electromagnetic stirring device with a frequency of 50 Hz and a stirring intensity of 230 rpm, and maintain for 30 min to allow the alloy elements to fully diffuse.

[0038] (3) Rare earth treatment stage: continue to cool to 690±2℃, add rare earth coating agent, the addition amount is 0.12% of the total weight of the alloy, stand and degas for 20 minutes, and use vacuum suction method to remove slag on the surface of the melt.

[0039] 3. Thin strip continuous casting and rolling, integrated production of continuous casting and rolling.

[0040] (1) Twin-roll continuous casting parameters: casting roll diameter Φ800 mm, roll gap 2.0 mm; melt pouring temperature 685 ° C, casting roll cooling water flow 30 m3 / h, cooling rate 1100K / s; output strip thickness 2.0±0.2mm, surface roughness Ra≤1.6μm.

[0041] (2) Multi-pass cold rolling process: Primary rolling: the strip is rolled to 1.2 mm with a deformation of 40% by a Φ450×1200 mm four-roll mill; intermediate annealing: flash annealing at 430 °C for 3 min in a protective atmosphere of N2+H2 mixed gas, with H2 accounting for 5%; secondary rolling: rolling to 0.6 mm with a deformation of 50%, and finally rolling to 0.3 mm after annealing, with a total deformation of 85%.

[0042] 4. Deformation heat treatment strengthening, solution-aging process.

[0043] (1) Solution treatment: The cold-rolled wire rod was heated to 510±5℃ at a rate of 10℃ / min, kept at this temperature for 30min, and then quenched in water at a temperature of 20±2℃ to ensure that the p-strengthening phase was completely dissolved.

[0044] (2) Two-level aging:

[0045] First-level aging: 120℃ for 8h, uniformity in the furnace ±3℃;

[0046] Secondary aging: 170℃ for 2h to promote the uniform precipitation of nano-scale Mg5Si6 phase and control the grain size at 7.5-8.2μm.

[0047] 2. Composite coating process

[0048] 1. Inner layer chemical nickel plating, plating solution preparation and plating.

[0049] (1) Plating solution components:

[0050] Nickel sulfate (NiSO4·6H2O): 25.0±0.5g / L;

[0051] Sodium hypophosphite (NaH2PO2·H2O): 30.0±1.0g / L;

[0052] Lactic acid (C3H6O3): 10.0±0.3g / L;

[0053] Thiourea (CH4N2S): 0.001 g / L (stabilizer).

[0054] (2) Pre-processing process:

[0055] Alkali washing: 50g / L NaOH solution, soak at 60℃ for 5min;

[0056] Acid activation: 10% H2SO4 solution, immersion at room temperature for 1 min;

[0057] Sensitization: SnCl2 10 g / L + HCl 40 mL / L, treatment at 40 ° C for 3 min.

[0058] (3) Plating operation: the plating solution temperature is maintained at 85±2℃, the pH value is adjusted to 4.6-4.8 with ammonia water, the wire speed is 1.5m / min, the coating thickness is 2.0±0.2μm, and the resistivity increase is ≤3%.

[0059] 2. Preparation of outer graphene modified coating and resin coating.

[0060] (1) Modified graphene dispersion: Carboxylated graphene with a particle size of 2-3 μm and an oxygen content of 8-10% was selected; 0.5 wt% of graphene was added to a polysiloxane resin with a viscosity of 1200 cP and dispersed on a three-roll mill until the viscosity was ≤300 cP.

[0061] (2) Coating and curing: die extrusion coating is used, and the coating wet film thickness is 5 μm; curing conditions: hot air circulation baking at 180±5℃ for 15 min to form a 3.0±0.3 μm dry film with a pencil hardness ≥2H.

[0062] 3. Continuous production line configuration

[0063] 1. Equipment layout and parameters, production line integrated design.

[0064] (1) Melting-continuous casting section: 5-ton regenerative melting furnace - twin-roll continuous casting machine - hydraulic shearing machine, with a fixed strip length of 2000 mm.

[0065] (2) Rolling heat treatment section: Four-roll reversible cold rolling mill, maximum rolling force 1500kN -- flash annealing furnace, power 350kW -- water quenching tank, volume 8m 3 .

[0066] (3) Coating winding section: chemical nickel plating tank, length 12m, resin coating die head, width 300mm, hot air curing oven, divided into three temperature zones: 80℃ / 120℃ / 180℃, automatic winding machine, tension control ±3N.

[0067] 2. Key process control points: coordinated control of tension and temperature.

[0068] (1) From continuous casting to rolling section: the strip running speed is 12 m / min, the tension is set at 200-250 N to prevent deviation; the rolling oil flow rate is 80 L / min, the spray angle is 45°, and the roller surface is lubricated.

[0069] (2) Coating section: The wire sag in the chemical plating tank is ≤3° to avoid uneven coating thickness; the wind speed in the curing furnace is 0.8-1.2m / s, and the temperature gradient is ±2℃ / m.

[0070] 4. Performance Testing and Quality Verification

[0071] 1. Mechanical properties test, tensile strength and ductility.

[0072] (1) Test standard: According to GB / T 228.1-2021 “Tensile test of metallic materials”, the sampling length is 250 mm and the gauge length is 50 mm.

[0073] (2) Results: Tensile strength: 395-405 MPa, 120% higher than traditional aluminum wires; elongation at break: 16.2-17.8%, meeting the bending requirements of wire harnesses.

[0074] 2.Corrosion resistance verification and composite coating protection effectiveness.

[0075] (1) Salt spray test: A neutral salt spray test was performed for 300 h according to ISO 9227 standard, with the sample tilted at a 45° angle. The results showed that the nickel layer had no substrate corrosion and only less than 5% white rust appeared on the surface; the graphene coating had no blistering or peeling, and the corrosion extension width at the scratch was ≤0.1 mm.

[0076] (2) Electrochemical test: Using a three-electrode system, the reference electrode is a saturated calomel electrode, and the charge transfer resistance Rct is measured:

[0077] Initial value: 1.25×10 5 Ω·cm 2 ;

[0078] After salt spray: 1.12×10 5 Ω·cm 2 , attenuation rate ≤10.4%.

[0079] 3.Electrical performance evaluation, conductivity and signal integrity.

[0080] (1) Conductivity test: using an eddy current conductivity meter with an accuracy of ±0.5% IACS, the result was 59.8-60.5% IACS, with a fluctuation range of ≤1.2%.

[0081] (2) High-frequency impedance: The characteristic impedance is tested in the 1-100MHz frequency range, and the fluctuation value is ≤±4.8%, which meets the CAN bus transmission requirements.

[0082] 5. Application Scenario Examples

[0083] 1. New energy vehicle high-voltage wiring harness, battery pack to motor main wiring harness.

[0084] (1) Wire gauge design: wire cross-sectional area 1.5mm 2 , 19 strands twisted, single wire diameter 0.2mm; insulation layer uses cross-linked polyolefin (XLPO), thickness 0.6mm.

[0085] (2) Installation verification: working voltage 800V DC, temperature rise ≤35K, ambient temperature 80℃; vibration test (GB / T28046.3): 30Hz-2000Hz frequency sweep without broken wires.

[0086] 2. Vehicle sensor wiring harness, radar and camera signal lines.

[0087] (1) Shielding structure: inner layer nickel-plated conductor + middle layer aluminum foil wrap, coverage ≥ 95% + outer layer tinned copper wire braid, coverage 85%; shielding effectiveness ≥ 90dB@1GHz (EN 50147 standard).

[0088] (2) Flexibility test: bending radius 5D, D is the wire diameter, number of cycles ≥ 500,000 times (ISO 6722); insulation resistance ≥ 100MΩ·km, 500V DC test.

[0089] Quantitative analysis of technical benefits

[0090] Material cost savings: Based on an annual production of 500,000 sets of wiring harnesses, replacing copper materials can reduce procurement expenditures by 192 million yuan. The copper price is 60,000 yuan / ton and the aluminum price is 21,000 yuan / ton.

[0091] Reduced energy consumption: The continuous production line saves 18% energy compared to the traditional segmented process, saving 4.5 million kWh of electricity annually, based on a single-line energy consumption of 0.9 kWh / kg.

[0092] Improved reliability: The salt spray corrosion rate is reduced from 0.015mm / yr to 0.003mm / yr, and the wiring harness life is extended from 8-10 years to 15 years.

[0093] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. The scope of patent protection of the present invention shall be based on the claims. Any equivalent structural changes made using the contents of the description of the present invention shall also be included in the scope of protection of the present invention.

Claims

1. A method for producing and processing an automobile wiring harness, characterized in that: The following steps are involved: (a) Alloy wire preparation: Al 92-95%, Fe 2.5-3.8%, Mg 1.2-1.8%, Cu 0.5-1.0%, RE 0.05-0.15% are mixed by mass, and then the wire is produced by strip casting, cold rolling, and aging treatment. (b) Composite coating: First, chemical nickel plating is performed to form a 2 μm inner layer, and then graphene-modified resin is coated to form a 3 μm outer layer.

2. The method for producing and processing an automotive wiring harness according to claim 1, wherein: In step (a), the smelting adopts three-stage temperature control: First-level temperature control, temperature controlled at 750℃ for slag removal; Secondary temperature control, temperature controlled at 720℃, adding Mg / Cu; Three-stage temperature control, temperature controlled at 690℃ with RE degassing; The temperature difference of each level is controlled within the range of ±30℃.

3. The method for producing and processing an automotive wiring harness according to claim 1, wherein: The thin strip continuous casting cooling rate is 10001200K / s, and the strip thickness is 2.0±0.2mm.

4. The method for producing and processing an automotive wiring harness according to claim 1, wherein: The cold rolling and aging process in step (a) is: Initial rolling stage: The continuous casting strip is cold rolled four times, and the total deformation is controlled at 83%-87%. Intermediate annealing: Flash annealing is performed after each rolling pass, with an annealing temperature of 425℃-435℃ and a holding time of 2.5-3.5min; Secondary rolling: rolling the strip to a thickness of 0.58-0.62mm, with a single deformation of 48%-52%; Final rolling after annealing: After annealing, the steel is rolled to the target thickness of 0.28-0.32mm, with a cumulative total deformation of 83%-87%; Solution treatment: quenching in water at 510℃±5℃, transfer time ≤15s; Two-stage aging: first-stage aging at 118℃-122℃ for 7.5-8.5h, second-stage aging at 168℃-172℃ for 1.8-2.2h.

5. The method for producing and processing an automobile wiring harness according to claim 1, characterized in that: The chemical plating solution in step (b) comprises the following components: 25±2 g / L nickel sulfate, 30±3 g / L sodium hypophosphite, and 10±1 g / L lactic acid. Plating is performed at 85±2° C. for 20 min.

6. The method for producing and processing an automotive wiring harness according to claim 1, characterized in that: The outer resin coating in step (b) is graphene-modified polysiloxane, with a graphene content of 0.4-0.6wt%, carboxyl modification, a particle size of 1-5μm, and a withstand voltage of ≥5kV after curing at 180°C.

7. The method for producing and processing an automobile wiring harness according to claim 3, characterized in that: The continuous casting strip is rolled to a target wire diameter by a four-roll cold rolling mill, and the roll gap pressure fluctuation is ±0.05 mm.

8. The method for producing and processing an automobile wiring harness according to claim 1, wherein: Online quality monitoring is also provided: an electrochemical impedance spectrometer is installed after the coating process, and an automatic alarm and shutdown will be issued if the impedance fluctuation exceeds ±5%.