A creep-resistant cable joint assembly for a core-shell structured rare earth-aluminum alloy conductor and a method of making the same

Abstract

This invention discloses an anti-creep cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors and its preparation method, belonging to the field of power cable connection technology. The connector assembly includes a crimping tube, a tapered crimping wing, a connecting part, and an inner anti-slip structure. The crimping tube is made of aluminum alloy material consistent with the core-shell structure rare-earth aluminum alloy conductor material system, composed of the following components: Ce 0.15–0.20%, Er 0.08–0.12%, Yb 0.05–0.08%, Zr 0.15–0.18%, Fe 0.10–0.13%, with the balance being Al. Its microstructure includes core-shell structure nano-precipitates, tensile strength ≥182 MPa, conductivity ≥61.5% IACS, and creep resistance superior to 1350 aluminum. The crimping wing has a tapered height distribution (0.05–0.15 mm / mm) along the longitudinal direction, ensuring uniform distribution of contact stress after crimping. The initial contact resistance after crimping is ≤5μΩ, and the contact resistance change rate after 1000 AC thermal cycles is ≤20%, meeting the requirements of GB / T 9327-2008. This invention, together with the core-shell structure rare earth aluminum alloy cable, forms an integrated patent protection of "cable + connector," applicable to the termination and intermediate connections of medium and high voltage power cables.

Description

Technical Field

[0001] This invention belongs to the field of power cable connection technology, specifically relating to a gradient anti-creep cable joint assembly suitable for core-shell structure rare earth aluminum alloy power cables and its preparation method, which can effectively solve the problems of increased contact resistance, heating, and loosening caused by creep in aluminum alloy cable joints. Background Technology

[0002] With the advancement of replacing copper with aluminum, rare earth aluminum alloy cables are being used more and more widely in the field of power transmission. However, the connection reliability of aluminum alloy cables has always been a core technical challenge restricting their large-scale application.

[0003] The main technical problems with aluminum alloy cable connectors are as follows:

[0004] First, aluminum alloy conductors are prone to creep under temperature cycling, leading to loosening of the joint. The creep tendency of pure aluminum conductors under heat and pressure can cause irreversible deformation of the terminals, resulting in decreased connection performance or even failure. Existing common copper-aluminum transition terminals often use ordinary aluminum materials (such as 1350 grade aluminum), which are susceptible to creep under long-term temperature changes, causing irreversible changes in their structural dimensions. If the crimping process is substandard, increased contact resistance can pose a risk of overheating and fire.

[0005] Secondly, the oxide film on the surface of aluminum alloy conductors significantly affects contact resistance. A dense aluminum oxide (Al2O3) film easily forms on the surface of aluminum alloy conductors. This oxide film has extremely high resistivity. If the pretreatment before crimping is improper or the crimping pressure is insufficient, the oxide film cannot be effectively broken up, which will lead to a significant increase in contact resistance and cause local overheating.

[0006] Third, the structural design of existing aluminum alloy cable connectors lacks specificity. Although there are related patents for aluminum alloy cable connectors in the existing technology (such as CN119401159A), their structural designs are not optimized for the material properties of core-shell structure rare earth aluminum alloy conductors. Most existing terminals are general-purpose designs, with the height and shape of the crimping wings evenly distributed longitudinally, lacking fine-grained control over the stress distribution between the conductor and the terminal.

[0007] Fourth, while the standard system for aluminum alloy cable connectors is becoming increasingly comprehensive, product supply is insufficient. GB / T 9327-2008, "Test Methods and Requirements for Crimped and Mechanical Connection Fittings for Conductors of Power Cables with Rated Voltage of 35kV and Below," stipulates that terminals must pass electrical and mechanical tests. Among these, 1000 AC thermal cycles are a crucial test for verifying the safety performance of conductors and terminals under operating conditions. However, existing aluminum alloy connector solutions capable of reliably passing 1000 thermal cycle tests remain limited.

[0008] Therefore, how to effectively suppress the increase in contact resistance and heat generation caused by creep while achieving reliable connection of aluminum alloy cables, develop an anti-creep cable joint assembly that perfectly matches the characteristics of core-shell structure rare earth aluminum alloy conductor materials, and build a systematic patent protection barrier through the integrated design of "cable + joint" remains a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0009] (I) Purpose of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of existing technologies and provide an anti-creep cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors and its preparation method. This connector assembly uses aluminum alloy material consistent with the core-shell structure rare-earth aluminum alloy conductor material system. Through a gradient-type crimping wing structure design and optimized crimping process, it effectively suppresses creep deformation under temperature cycling, achieving long-term stable contact resistance (≤5μΩ). Furthermore, it forms a systematic technological barrier through integrated patent protection of the "cable + connector".

[0011] (II) Technical Solution

[0012] 1. Connector assembly structure

[0013] A creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors, characterized in that it comprises:

[0014] The crimping tube 1 is sleeved on the end of the rare earth aluminum alloy conductor of the core-shell structure; the crimping wing 2 is set on the outside of the crimping tube; the connecting part 3 (copper-aluminum transition section or pure aluminum connecting end) is set on the front end of the crimping tube; and the anti-slip structure 4 is set on the inner wall of the crimping tube.

[0015] Preferably, the press-fit tube and press-fit wing are made of aluminum alloy material consistent with the rare earth aluminum alloy conductor material system of the core-shell structure, so as to eliminate additional creep caused by the difference in thermal expansion coefficient of different materials.

[0016] Preferably, the crimping wing has a gradually increasing height distribution along the longitudinal direction of the crimping tube: the height of the crimping wing near the conductor end gradually increases, forming a progressive portion that extends along the full length of the crimping wing.

[0017] Preferably, the number of the crimping wings is 2 to 6, and they are evenly distributed along the circumference of the crimping tube.

[0018] Furthermore, the connector assembly meets all of the following technical requirements:

[0019] Contact resistance after crimping: ≤5μΩ (initial value);

[0020] Contact resistance change rate after 1000 AC heating cycles: ≤20%;

[0021] The increase in contact resistance after crimping is ≤ 5% of the initial value before crimping;

[0022] Tensile strength: ≥ 80% of the conductor's rated tensile strength;

[0023] Operating temperature range: -40℃~125℃.

[0024] 2. Press-fit pipe material

[0025] The press-fit tube and press-fit wing are made of core-shell structure rare earth aluminum alloy material, characterized by being composed of the following components by mass percentage:

[0026] Cerium (Ce): 0.15–0.20%

[0027] Erbium (Er): 0.08–0.12%

[0028] Ytterbium (Yb): 0.05–0.08%

[0029] Zirconium (Zr): 0.15–0.18%

[0030] Iron (Fe): 0.10–0.13%

[0031] The balance is aluminum (Al) and unavoidable impurities.

[0032] Furthermore, the microstructure of the press-fit tube material includes a core-shell structured nano-precipitated phase and a nano-scale dispersed phase:

[0033] The core-shell structured nanoprecipitate is an Al3(RE, Zr) composite nanoprecipitate, which contains a rare earth element-rich (Ce, Er, Yb) core and a Zr-rich shell. The sum of the atomic concentrations of rare earth elements in the core accounts for more than 90% of the total number of atoms in the core of the precipitate, and the atomic concentration of Zr in the shell accounts for more than 85% of the total number of atoms in the shell of the precipitate.

[0034] The nanoscale dispersed phase is nanoscale Al that is encapsulated or pinned by the core-shell structured nanoscale precipitates. 13 The Fe4 dispersed phase has an equivalent spherical average diameter of no more than 50 nanometers.

[0035] Furthermore, the tensile strength of the press-fit tube material is ≥182MPa, the conductivity is ≥61.5%IACS, the elongation is ≥22%, and the creep deformation is more than 40% smaller than that of ordinary aluminum materials (such as 1350 aluminum).

[0036] 3. Gradient-type press-fit wing structure

[0037] The gradient press-fit wing structure is one of the core innovations of this invention in achieving anti-creep performance.

[0038] Preferably, in the non-crimping state, each crimping wing has a height (h(L)) that gradually increases toward the end of the conductor to be crimped in the longitudinal direction.

[0039] Preferably, the progressive portion of the tapered crimping wing extends along the full length of each crimping wing, so that the contact stress between the conductor and the crimping tube after crimping transitions evenly from the conductor end to the root, avoiding stress concentration.

[0040] Furthermore, the height variation rate of the gradually changing crimping wing is 0.05 to 0.15 mm / mm, so that the standard deviation of the contact stress distribution on the conductor surface after crimping is ≤ 15% of the average crimping stress.

[0041] 4. Anti-slip structure

[0042] The anti-slip structure is installed on the inner wall of the crimping tube to increase the friction between the crimping tube and the conductor, and to prevent the conductor from axially slipping due to thermal expansion and contraction under temperature cycling.

[0043] Preferably, the anti-slip structure is an annular serration or threaded structure on the inner wall of the press-fit pipe.

[0044] Preferably, the tooth height of the anti-slip structure is 0.1 to 0.3 mm, and the tooth pitch is 0.5 to 2.0 mm.

[0045] 5. Connecting parts

[0046] The connecting part is located at the front end of the crimping tube and is used to connect to the equipment end or other cables.

[0047] Preferably, the connecting part is a copper-aluminum transition section, which is connected by copper-aluminum friction welding or copper-aluminum brazing process. The aluminum end is integrally formed with the pressure pipe, and the copper end is connected to the equipment.

[0048] Preferably, the connecting part is a pure aluminum connecting end with a silver or tin plating finish, and is directly connected to the equipment.

[0049] 6. Preparation method

[0050] A method for preparing a creep-resistant cable connector assembly adapted to a core-shell structure rare-earth aluminum alloy conductor, characterized by comprising two stages: preparation of crimp tube material and molding of the connector assembly.

[0051] (I) Preparation stage of crimping pipe material

[0052] Step 1, casting: Prepare raw materials according to the stated composition ratio. The purity of the pure Al used is ≥99.99%, and the purity of the intermediate alloy is ≥99.5%. Melt under argon protection and cast into ingots.

[0053] Step 2, Differentiated two-stage homogenization treatment: The ingot is subjected to the first stage homogenization treatment by heating to 420-425℃ and holding for 4.5-5.5 hours; then the second stage homogenization treatment is performed by heating to 540-545℃ and holding for 8-10 hours, and then air-cooled after being removed from the furnace.

[0054] Step 3, hot deformation processing: The homogenized ingot is heated to 460-500℃ and hot extruded or hot rolled to form a tube blank;

[0055] Step 4, Solution treatment and aging treatment: The tube blank is solution treated by heating to 560-565℃ and holding for 1.5-2.0 hours, followed by water quenching (cooling rate ≥80℃ / min); then aging treatment is performed by heating to 242-248℃ and holding for 6.5-7.5 hours.

[0056] Step 5, Annealing treatment: Anneal the aged pipe by heating it to 310-330℃ and holding it for 2.0-3.0 hours, then cooling it in the furnace;

[0057] Step 6, Machining: The annealed pipe is machined to form the press-fit pipe body, the inner anti-slip structure, and the gradient press-fit wing profile.

[0058] (II) Connector Assembly Molding Stage

[0059] Step 7, Surface treatment: Clean and remove oxide film from the inner wall of the crimped tube and the surface of the conductor;

[0060] Step 8, Conductor Insertion: Insert the end of the core-shell structured rare-earth aluminum alloy conductor into the crimping tube;

[0061] Step 9, crimping: Use a special crimping die to crimp the crimping wings. The crimping pressure is controlled at 80-150kN. After crimping, the crimping wings are tightly attached to the conductor.

[0062] Step 10, Connection forming (optional): For copper-aluminum transition joints, after crimping, the copper end and the aluminum end are connected by friction welding or brazing.

[0063] Step 11, Performance Testing: Perform connector performance testing according to GB / T 9327-2008, including contact resistance testing, 1000 AC thermal cycle tests, etc.

[0064] Step 12, anti-corrosion treatment: Apply an anti-corrosion coating to the connector assembly or encapsulate it with heat shrink tubing.

[0065] (III) Beneficial Effects

[0066] Compared with the prior art, the present invention has the following significant advantages:

[0067] 1. Consistent material system, eliminating thermal expansion mismatch: The crimping tube and crimping wing of the joint assembly of the present invention are made of aluminum alloy material consistent with the rare earth aluminum alloy conductor material system of the core-shell structure, eliminating the additional creep and stress relaxation caused by the difference in thermal expansion coefficients of different materials (such as ordinary aluminum and core-shell structure aluminum alloy).

[0068] 2. Gradual Height Design for Optimized Stress Distribution: This invention utilizes a gradually increasing height design for the crimping wing along the longitudinal direction to ensure a uniform transition of contact stress between the conductor and the crimping tube after crimping, preventing stress concentration and effectively suppressing creep deformation under temperature cycling. The standard deviation of the contact stress distribution is ≤15% of the average stress.

[0069] 3. Long-term stable contact resistance: Through the triple collaborative design of consistent material system + gradient pressing wings + anti-slip structure, the contact resistance after pressing is ≤5μΩ, and the contact resistance change rate after 1000 AC electric heating cycles is ≤20%, which meets the strict requirements of GB / T 9327-2008.

[0070] 4. Excellent creep resistance: The creep deformation of the core-shell structure rare earth aluminum alloy material is more than 40% smaller than that of ordinary aluminum materials (such as 1350 aluminum). Combined with the stress uniformity design of the gradient press wing, the dimensional stability of the joint under long-term temperature cycling is significantly improved.

[0071] 5. Establishing integrated patent protection for "cable + connector": This invention, together with the patent for core-shell structure rare-earth aluminum alloy cables, forms a systematic technological barrier. If competitors only produce core-shell structure cables but cannot provide compliant connector components based on this invention, they will find it difficult to achieve reliable connections, significantly raising the barrier to market competition.

[0072] 6. Compliance with national standards: The test methods and requirements for the connector assembly of this invention comply with GB / T 9327-2008 "Test methods and requirements for crimp and mechanical connection fittings for conductors of power cables with rated voltage of 35kV and below".

[0073] 7. Broad application prospects: The connector assembly of this invention is suitable for terminal and intermediate connections of core-shell structure rare earth aluminum alloy power cables, and can be widely used in urban power distribution network transformation, new energy power station collection lines, industrial power distribution and other fields. Attached Figure Description

[0074] Figure 1 This is a schematic diagram of the longitudinal section structure of the anti-creep cable joint assembly according to Embodiment 1 of the present invention. In the figure: 1-crimping tube; 2-crimping wing (gradual height distribution, height change rate 0.05~0.15mm / mm); 3-connecting part; 4-anti-slip structure (inner wall serrations); 5-core shell structure rare earth aluminum alloy conductor.

[0075] Figure 2This is a comparison chart of the contact resistance change rate after 1000 thermal cycles between Embodiment 1 of the present invention and a traditional aluminum alloy connector (1350 aluminum material). Detailed Implementation

[0076] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in further detail below with reference to the accompanying drawings and embodiments. However, the following embodiments are only used to explain this invention and do not constitute a limitation on the scope of protection of this invention.

[0077] Test method description:

[0078] The performance tests of the embodiments and comparative examples of this invention were all conducted in accordance with the following standards:

[0079] Tensile strength: Tested according to GB / T 228.1-2021 "Metallic materials, tensile testing - Part 1: Test method at room temperature";

[0080] Conductivity: Tested according to GB / T 351-2019 "Methods for Measurement of Resistivity of Metallic Materials";

[0081] Contact resistance: Tested according to GB / T 9327-2008 "Test methods and requirements for crimp and mechanical connection hardware for conductors of power cables with rated voltage of 35kV and below";

[0082] 1000 AC electric heating cycle test: conducted according to GB / T 9327-2008 (heating current to bring the conductor temperature to 120℃±5℃, natural cooling to room temperature, 1000 cycles), and the change rate of contact resistance before and after the cycle was measured;

[0083] Creep resistance: Tested according to GB / T 2039-2012 "Metallic materials uniaxial tensile creep test method".

[0084] Raw material description:

[0085] The purity of the raw materials used in the embodiments of the present invention is as follows:

[0086] Pure Al: purity ≥ 99.99%;

[0087] Al-10%Ce, Al-5%Er, Al-5%Yb, Al-4%Zr, and Al-10%Fe master alloys: all with a purity ≥99.5%.

[0088] Core-shell structure characterization methods:

[0089] In this embodiment of the invention, the microstructure and elemental distribution of the core-shell structured nanoprecipitates were characterized using transmission electron microscopy (TEM) combined with energy dispersive X-ray spectroscopy (EDS), in accordance with GB / T 47182-2026 "Microbeam analysis and analytical electron microscopy for measuring the shell wall thickness of core-shell particles".

[0090] Example 1 (35kV medium and high voltage cable joint assembly, copper-aluminum transition type)

[0091] 1. Preparation of crimping tube material

[0092] 1.1 Batching: Take pure Al (purity ≥ 99.99%), Al-10% Ce (purity ≥ 99.5%), Al-5% Er (purity ≥ 99.5%), Al-5% Yb (purity ≥ 99.5%), Al-4% Zr (purity ≥ 99.5%), and Al-10% Fe (purity ≥ 99.5%) master alloys and mix them according to the final composition of Ce 0.18%, Er 0.10%, Yb 0.06%, Zr 0.16%, Fe 0.12%, with the balance being Al.

[0093] 1.2 Melting and casting: Melting is carried out at 750℃ under argon protection, and after being stirred evenly, it is cast into ingots.

[0094] 1.3 Differentiated two-stage homogenization: The ingot is placed in a homogenization furnace, first held at 423℃ for 5.0 hours, then heated to 542℃ and held for 9.0 hours, and then removed from the furnace and air-cooled.

[0095] 1.4 Hot Deformation: The homogenized ingot is heated to 480℃ and hot extruded to form a tube blank.

[0096] 1.5 Solution treatment and aging: The tube blank was solution treated at 562℃ for 1.8 hours and then water quenched (cooling rate ≥80℃ / min); then aged at 245℃ for 7.0 hours.

[0097] 1.6 Annealing treatment: The aged pipe is kept at 320℃ for 2.5 hours and then cooled to room temperature in the furnace.

[0098] 1.7 Machining: The annealed pipe is machined to form the crimped pipe body (inner diameter matches the outer diameter of the conductor), the inner wall annular serrated anti-slip structure (tooth height 0.2mm, tooth pitch 1.0mm), and the gradient crimping wing profile (height change rate 0.10mm / mm).

[0099] 2. Connector assembly molding

[0100] 2.1 Material performance verification: The tensile strength of the obtained press-fit tube material was 184 MPa, the conductivity was 61.6% IACS, the elongation was 23.2%, and the creep deformation was about 42% smaller than that of 1350 aluminum.

[0101] 2.2 Surface treatment: The inner wall of the press-fit tube and the surface of the rare earth aluminum alloy conductor of the core-shell structure are cleaned and the oxide film is removed.

[0102] 2.3 Conductor insertion: Insert the end of the core-shell structured rare earth aluminum alloy conductor into the crimping tube.

[0103] 2.4 Crimping: The crimping wings are crimped using a special crimping die at a pressure of 120kN. After crimping, the crimping wings are tightly bonded to the conductor.

[0104] 2.5 Connection Forming: The copper end is connected to the aluminum end by friction welding to form a copper-aluminum transition joint.

[0105] 2.6 Performance Testing:

[0106] Initial contact resistance: 4.2μΩ (≤5μΩ, acceptable);

[0107] Contact resistance change rate after 1000 AC heating cycles: +12% (≤20%, qualified);

[0108] Tensile strength after crimping: 160MPa (≥ 80% of the conductor's rated tensile strength of 184MPa = 147MPa, qualified);

[0109] Contact resistance increment: +3.8% (≤5%, acceptable).

[0110] 2.7 Corrosion protection: The connector assembly is encapsulated with heat shrink tubing.

[0111] Example 2 (10kV medium voltage cable joint assembly, pure aluminum end type)

[0112] 1. Preparation of crimping tube material

[0113] 1.1 Ingredients: The ingredients were prepared according to the final composition of Ce 0.15%, Er 0.12%, Yb 0.05%, Zr 0.17%, Fe 0.11%, with the balance being Al. The purity and source of the raw materials were the same as in Example 1.

[0114] 1.2 Melting and casting: Same as in Example 1.

[0115] 1.3 Differentiated two-stage homogenization: heat at 421℃ for 5.5 hours, then heat at 541℃ for 8.5 hours.

[0116] 1.4 Thermal deformation: Same as in Example 1.

[0117] 1.5 Solution treatment and aging: Solution treatment at 561℃ for 1.5 hours followed by water quenching; aging treatment at 243℃ for 7.2 hours.

[0118] 1.6 Annealing treatment: Hold at 315℃ for 2.8 hours, then cool with the furnace.

[0119] 1.7 Machining: Machining to form the press-fit pipe body, the inner wall anti-slip structure, and the gradient press-fit wing profile (height change rate 0.08mm / mm).

[0120] 2. Connector assembly molding

[0121] 2.1 Material performance verification: The obtained press-fit tube material was tested and found to have a tensile strength of 182 MPa, a conductivity of 61.8% IACS, an elongation of 23.8%, and a creep deformation of about 43% less than that of 1350 aluminum.

[0122] 2.2 Surface treatment: Same as in Example 1.

[0123] 2.3 Conductor insertion: Same as in Example 1.

[0124] 2.4 Crimping: Crimping pressure 100kN.

[0125] 2.5 Connecting part forming: The surface of the pure aluminum end is silver plated.

[0126] 2.6 Performance Testing:

[0127] Initial contact resistance: 3.8μΩ (≤5μΩ, acceptable);

[0128] Contact resistance change rate after 1000 AC heating cycles: +10% (≤20%, qualified);

[0129] Contact resistance increment: +3.2% (≤5%, acceptable).

[0130] Example 3 (Large Cross-Section 35kV Cable Joint Assembly)

[0131] 1. Preparation of crimping tube material

[0132] 1.1 Ingredients: The ingredients were prepared according to the final composition of Ce 0.20%, Er 0.08%, Yb 0.08%, Zr 0.15%, Fe 0.13%, with the balance being Al. The purity and source of the raw materials were the same as in Example 1.

[0133] 1.2 Melting and casting: Same as in Example 1.

[0134] 1.3 Differentiated two-stage homogenization: heat at 424℃ for 4.8 hours, then heat at 544℃ for 9.5 hours.

[0135] 1.4 Thermal deformation: Same as in Example 1.

[0136] 1.5 Solution treatment and aging: Solution treatment at 564℃ for 2.0 hours followed by water quenching; aging treatment at 247℃ for 6.8 hours.

[0137] 1.6 Annealing treatment: Hold at 325℃ for 2.2 hours, then cool with the furnace.

[0138] 1.7 Machining: Machining to form a large-size press-fit tube body (compatible with 185mm). 2 Conductor), inner wall anti-slip structure and gradient crimp wing profile (height change rate 0.12mm / mm).

[0139] 2. Connector assembly molding

[0140] 2.1 Material performance verification: The obtained press-fit tube material was tested and found to have a tensile strength of 185 MPa, a conductivity of 61.5% IACS, an elongation of 22.5%, and a creep deformation of about 41% less than that of 1350 aluminum.

[0141] 2.2 Performance Testing:

[0142] Initial contact resistance: 4.5μΩ (≤5μΩ, acceptable);

[0143] Contact resistance change rate after 1000 AC heating cycles: +15% (≤20%, qualified);

[0144] Contact resistance increment: +4.2% (≤5%, acceptable).

[0145] Comparative Example 1 (Traditional 1350 aluminum connector assembly)

[0146] A standard 1350 aluminum press-fit connector assembly was used as a comparative example. Testing showed that the tensile strength of 1350 aluminum is approximately 120 MPa, and its conductivity is approximately 61.0% IACS. Its creep resistance is significantly lower than that of the embodiment of this invention. The initial contact resistance is approximately 8 μΩ, and the contact resistance change rate after 1000 AC heating cycles is approximately +35%, failing to meet the requirement of ≤20%.

[0147] Comparative Example 2 (Ordinary Aluminum Alloy Connector Assembly - Coreless Shell Structure)

[0148] A standard AA8030 aluminum alloy connector assembly was used as a comparative example. Testing showed that AA8030 aluminum has a tensile strength of approximately 150 MPa, a conductivity of approximately 57% IACS, and lower creep resistance than the embodiment of this invention. The initial contact resistance was approximately 6 μΩ, and after 1000 AC heating cycles, the contact resistance change rate was approximately +25%, close to the standard upper limit.

[0149] Summary of Performance of Examples and Comparative Examples

[0150]

[0151] Conclusion: The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors of the present invention (Examples 1-3) significantly outperforms traditional 1350 aluminum and AA8030 aluminum alloy connector assemblies in terms of initial contact resistance (≤4.5μΩ), contact resistance change rate after 1000 thermal cycles (≤15%), and creep resistance. The gradient press-fit wing structure combined with the core-shell structure material system achieves long-term stability of contact resistance.

[0152] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors, characterized in that, include: A crimping tube is fitted onto the end of a core-shell structure rare-earth aluminum alloy conductor; a crimping wing is provided on the outside of the crimping tube; A connecting part located at the front end of the crimping tube; an anti-slip structure located on the inner wall of the crimping tube; The press-fit tube and press-fit wing are made of core-shell structure rare earth aluminum alloy material, which is composed of the following components by mass percentage: Ce 0.15-0.20%, Er 0.08-0.12%, Yb 0.05-0.08%, Zr 0.15-0.18%, Fe 0.10-0.13%, with the balance being Al and unavoidable impurities.

2. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The microstructure of the press-fit tubing material includes a core-shell structured nano-precipitated phase and a nano-scale dispersed phase. The core-shell structured nanoprecipitate is an Al3(RE,Zr) composite nanoprecipitate, which contains a rare earth element-rich core and a Zr-rich shell. The sum of the atomic concentrations of rare earth elements in the core accounts for more than 90% of the total number of atoms in the core of the precipitate, and the atomic concentration of Zr in the shell accounts for more than 85% of the total number of atoms in the shell of the precipitate. The nanoscale dispersed phase is nanoscale Al that is encapsulated or pinned by the core-shell structured nanoscale precipitates. 13 The Fe4 dispersed phase has an equivalent spherical average diameter of no more than 50 nm.

3. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The crimping wing has a gradually increasing height distribution along the longitudinal direction of the crimping tube: the height of the crimping wing near the conductor end gradually increases, with a height change rate of 0.05 to 0.15 mm / mm.

4. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The number of crimping wings is 2 to 6, and they are evenly distributed along the circumference of the crimping tube.

5. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The anti-slip structure is an annular sawtooth or threaded structure on the inner wall of the press-fit pipe, with a tooth height of 0.1 to 0.3 mm and a tooth pitch of 0.5 to 2.0 mm.

6. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The connecting part is a copper-aluminum transition section or a pure aluminum connecting end, and the copper-aluminum transition section is connected by copper-aluminum friction welding or copper-aluminum brazing process.

7. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The initial contact resistance of the connector assembly after crimping is ≤5μΩ, and the contact resistance change rate after 1000 AC heating cycles is ≤20%.

8. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The pressure-fitting tube material has a tensile strength ≥182MPa, conductivity ≥61.5%IACS, elongation ≥22%, and creep resistance with creep deformation more than 40% smaller than that of 1350 aluminum.

9. The creep-resistant cable connector assembly adapted to core-shell structure rare-earth aluminum alloy conductors according to claim 1, characterized in that, The connector assembly meets the requirements of GB / T 9327-2008 "Test methods and requirements for crimp and mechanical connection fittings for conductors of power cables with rated voltage of 35kV and below".

10. A method for preparing an anti-creep cable joint assembly adapted to a core-shell structure rare-earth aluminum alloy conductor as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Step 1, casting: Prepare raw materials according to the stated composition ratio, melt them under a protective atmosphere, and cast them into ingots; Step 2, Differentiated two-stage homogenization treatment: The ingot is subjected to the first stage homogenization treatment by heating to 420-425℃ and holding for 4.5-5.5 hours; then the second stage homogenization treatment is performed by heating to 540-545℃ and holding for 8-10 hours. Step 3, hot deformation processing: The homogenized ingot is heated to 460-500℃ and hot extruded to form a tube blank; Step 4, Solution treatment and aging treatment: The tube blank is solution treated by heating to 560-565℃ and holding for 1.5-2.0 hours, then water quenched at a cooling rate of ≥80℃ / min; then aging treatment is performed by heating to 242-248℃ and holding for 6.5-7.5 hours. Step 5, Annealing treatment: Anneal the aged pipe by heating it to 310-330℃ and holding it for 2.0-3.0 hours; Step 6, Machining: The annealed pipe is machined to form the crimped pipe body, the inner anti-slip structure, and the gradient crimping wing profile. Step 7, Surface treatment: Clean and remove oxide film from the inner wall of the press-fit pipe; Step 8, crimping: Insert the end of the core-shell structure rare earth aluminum alloy conductor into the crimping tube, and crimp the crimping wings using a special crimping mold; Step 9, Performance testing: Perform connector performance testing according to GB / T 9327-2008.

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