Self-lubricating wear-resistant composite wire rope and preparation method thereof

Abstract

This invention discloses a self-lubricating, wear-resistant composite metal wire rope and its preparation method. The wire rope includes a core and at least one layer of strands twisted around it. The strands are formed by twisting multiple outer steel wires together. The core is made of a porous sintered metal material, with solid lubricant impregnated in its pores. Multiple micro-pits are formed on the surface of the outer steel wires through a composite process of electrodeposition and rolling. Liquid or semi-solid lubricant is stored in the pits, and micro-gaps are provided between adjacent strands and between the strands and the core. The preparation method includes: sintering of the gradient-pore core and vacuum impregnation with solid lubricant → pulse electrodeposition and rolling of the outer steel wire surface → filling with lubricant containing microcapsules, precise twisting and control of micro-gaps → pre-stretching and running-in to form an initial self-lubricating layer and depositing a diamond-like carbon or molybdenum disulfide composite film. This invention achieves three-level synergistic self-lubrication of "solid-liquid-film," eliminating the need for external oiling and comprehensively reducing friction and wear.

Description

Technical Field

[0001] This invention relates to the field of metal rope technology, specifically to a composite metal wire rope with self-lubricating and wear-resistant functions and its preparation method. Background Technology

[0002] Wire ropes, as important flexible load-bearing components, are widely used in elevator hoisting, lifting machinery, bridge stay cables, mining hoisting equipment, and various traction transmission systems. During operation, repeated bending, stretching, and friction are unavoidable between the internal steel wires, between the wires and the rope core, and between the wire rope and the external sheave (or drum). Currently, most mainstream ordinary wire ropes on the market undergo initial lubrication by dipping or spraying grease (oil) before leaving the factory. This relies on the grease forming an oil film on the steel wire surface to reduce the coefficient of friction, minimize fretting wear, and prevent corrosion. However, in actual long-term service, existing wire ropes and lubrication technologies have the following significant drawbacks:

[0003] (1) The lubricating medium is easily lost and the adaptability to working conditions is poor: When ordinary steel wire ropes are subjected to repeated bending, tensile deformation and high-line contact friction with the rope pulley, the grease coated on the surface and between the strands will be quickly squeezed out, lost or decomposed by heat under mechanical extrusion and centrifugal action. Once the grease fails, the steel wire directly enters the "dry friction" state, which leads to increased internal fretting wear, a sharp increase in the single wire breakage rate, and finally fatigue fracture. Experimental and field data show that the life reduction of steel wire rope due to lubrication failure can reach more than 50%.

[0004] (2) Difficult post-maintenance and significant safety blind spots: For special application environments such as high-altitude tower cranes, cable cars, deep-well mine hoists, and enclosed elevator shafts, operators cannot frequently and evenly replenish the entire long-distance wire rope with regular oil. Even with external oil replenishment through manual or automatic dripping devices, the lubricating oil is difficult to penetrate to the contact interface between the strands and the central wire inside the wire rope, resulting in the core load-bearing parts being in a state of lack of oil or dry friction for a long time. This "wet outside, dry inside" phenomenon makes internal damage difficult to detect by routine surface inspection, which can easily lead to sudden rope breakage accidents.

[0005] (3) Structural design separates function and load-bearing capacity: Traditional steel wire ropes are designed with an emphasis on tensile strength and flexibility, and lubrication is only regarded as a post-processing procedure or external consumable. The fundamental contradiction of "fretting wear - lubrication loss - fatigue failure" is not solved from the perspective of material composite and structural synergy.

[0006] Therefore, developing a metal wire rope capable of long-lasting, stable lubrication and wear resistance without relying on external lubrication, thereby significantly extending its fatigue life and reducing maintenance risks and costs, has become a pressing technical challenge in this field. Addressing the technical bottlenecks of existing technologies, such as easy grease loss, inability to replenish lubrication in confined / high-altitude environments, and shortened lifespan due to internal fretting wear, this invention provides a novel self-lubricating wear-resistant composite metal wire rope and its preparation method. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to overcome the defects of existing steel wire ropes, such as easy loss of lubricating grease under repeated bending and friction conditions, inability to replenish oil in high-altitude or confined environments, and shortened life due to internal fretting wear. The present invention provides a composite metal wire rope with long-lasting self-lubricating function and wear resistance, and its preparation method.

[0008] The technical solution of this invention is: a self-lubricating wear-resistant composite metal wire rope, comprising a core and at least one layer of strands twisted outside the core, wherein the strands are formed by twisting multiple outer steel wires together, the core is made of a porous sintered metal material, and its pores are impregnated with a solid lubricant; the surface of the outer steel wires is formed with multiple micro-pits by an electrodeposition and rolling composite process, and the micro-pits store liquid or semi-solid lubricant; micro-gaps are provided between adjacent strands and between the strands and the core, the width of the micro-gaps being 0.03 to 0.08 mm.

[0009] Preferably, in the above-mentioned self-lubricating wear-resistant composite metal wire rope, the porous sintered metal material is sintered bronze, sintered iron-based alloy or sintered stainless steel, with a porosity of 15-35% and an average pore diameter of 5-50 μm.

[0010] Preferably, in the above-mentioned self-lubricating wear-resistant composite metal wire rope, the solid lubricant is one or more of molybdenum disulfide, tungsten disulfide, graphite, and polytetrafluoroethylene.

[0011] Preferably, in the above-mentioned self-lubricating wear-resistant composite metal wire rope, the diameter of the micro-pits is 10-100μm, the depth is 5-30μm, and their area coverage is 15-40% of the surface area of ​​the outer steel wire.

[0012] Preferably, in the above-mentioned self-lubricating wear-resistant composite metal wire rope, the liquid or semi-solid lubricant is lithium-based grease, polyurea-based grease, or perfluoropolyether grease, with a viscosity grade of NLGI0 to 2#.

[0013] Preferably, in the above-mentioned self-lubricating wear-resistant composite metal wire rope, the width of the micro-gap is 0.05 mm, and the allowable width deviation is ±0.01 mm, which can be used to accommodate wear debris and promote heat dissipation.

[0014] Preferably, in the above-mentioned self-lubricating wear-resistant composite metal wire rope, the twisting direction of the strands is right-hand cross-twist or left-hand cross-twist, and the twist pitch is 6 to 8 times the diameter of the strands.

[0015] The present invention also provides a method for making a self-lubricating and wear-resistant composite metal wire rope, comprising the following steps:

[0016] Step (1) Preparation of porous sintered metal rope core: Metal powder and pore-forming agent are layered and stacked in a gradient from inner to outer particle size, and pressed into a rope core blank. The blank is then sintered under a protective atmosphere to obtain a porous sintered metal rope core with a decreasing porosity gradient from the inside to the outside. The large pores inside serve as long-term oil storage chambers, while the micropores outside control the slow release rate of the lubricant. Solid lubricant powder is mixed with 0.5-3% by mass of nano-tungsten disulfide or nano-graphene, and a surfactant is added. The mixture is then ultrasonically dispersed to allow the nanoparticles to be uniformly adsorbed onto the inner wall of the pores. After curing, a strong-adhesion composite lubricating film is formed, which improves the lubrication durability under high temperature and heavy load. The treated mixed powder is then dispersed in a solvent to form a suspension. The solid lubricant is then filled into the pores of the rope core by vacuum impregnation or pressure impregnation, followed by drying and curing.

[0017] Step (II) Surface Micro-Pit Treatment of Outer Steel Wire: The outer steel wire to be treated is placed in an electrodeposition tank. An electrodeposition layer with micron-sized protrusions is formed on the surface of the outer steel wire by electrodeposition. During electrodeposition, a positive pulse current is used with a frequency of 500–2000 Hz and a duty cycle of 10–30%. The electroplating solution used for electrodeposition is a mixed solution of nickel sulfate, nickel chloride, and boric acid, so that the micron-sized protrusions on the surface of the electrodeposition layer are distributed in an orderly array. Then, a rolling tool is used to roll the surface of the outer steel wire, so that the protrusions in the electrodeposition layer are flattened and formed into random patterns. The fabric has micro-pits, and the femtosecond laser is used to create grooves or textures with a depth of 5-15 μm at the bottom and edges of the micro-pits, forming a multi-scale composite oil storage structure. This multi-scale composite oil storage structure can enhance the locking capacity of liquid / semi-solid lubricants and the uniformity of pressure overflow. Liquid or semi-solid lubricants are filled into each micro-pit, and the filled liquid / semi-solid lubricants may contain microcapsules with self-healing function (the wall material is urea-formaldehyde resin, and the core material is lubricating oil or containing extreme pressure additives). When the steel wire is heated by friction, the microcapsules rupture and release the replenishing lubricant, realizing dynamic self-healing lubrication.

[0018] Step (III) Twisting and Micro-gap Control: The multiple outer steel wires processed in Step (II) are twisted into a strand, and the twisting tension and pitch of each strand are controlled. Then, the multiple strands are twisted around the rope core obtained in Step (I). A laser displacement sensor and a capacitive gap detection module are integrated into the twisting equipment to measure the distance between the strands and between the strands and the rope core in real time. The tension (fluctuation range ≤ ±2%) and radial compression of each strand are independently adjusted by a servo motor, and a closed-loop PID algorithm is introduced to dynamically adjust the deformation, so that the distance between adjacent strands and between the strands and the rope core is controlled. Micro-gaps with a width of 0.03–0.08 mm are formed between the wires, with a width deviation of ≤ ±0.005 mm, resulting in the finished metal wire rope. After twisting, the entire metal wire rope is subjected to axial pre-tension with a load of 15–25% of the breaking tensile force, and is run-in at a low speed of 10–30 r / min for 30–60 min. This allows the liquid or semi-solid lubricant in the micro-dimples to seep evenly to the surface of the micro-gaps, while the solid lubricant in the pores of the rope core is partially transferred to the surface of the micro-gaps under friction, together forming an initial self-lubricating layer.

[0019] Step (iv) Deposition of composite film on outer surface: After the twisted and run-in metal wire rope in step (iii) is obtained, a diamond-like carbon or molybdenum disulfide composite film with a thickness of 0.5 to 2 μm is deposited on the outer surface of the wire rope using plasma-enhanced chemical vapor deposition. This film works synergistically with the lubricant in the micro-pits to significantly reduce the friction coefficient between the wire rope and the external wheel groove, while preventing the micro-gap from being blocked by external contaminants.

[0020] Preferably, in the above-mentioned method for self-lubricating wear-resistant composite metal wire rope, in step (i): the pore-forming agent is urea, ammonium bicarbonate or sodium chloride, and its addition amount is 15-35% of the volume of metal powder; the sintering temperature is 800-1100℃, and the sintering time is 1-4h.

[0021] Preferably, in the above-mentioned method for self-lubricating wear-resistant composite metal wire rope, in step (ii): the rolling process uses a carbide roller, the rolling force is 50-200N, and the rolling speed is 0.5-5m / min.

[0022] Preferably, the method for the above-mentioned self-lubricating wear-resistant composite metal wire rope further includes, between steps (ii) and (iii): sequentially performing stepped ultrasonic cleaning, vacuum plasma activation treatment, and vacuum drying treatment on the outer steel wire with micro-pits on its surface. The stepped cleaning includes cleaning with a weakly alkaline degreasing solution containing corrosion inhibitors and cleaning with deionized water and nonionic surfactants. The vacuum plasma activation treatment uses an argon / oxygen mixed gas with a radio frequency power of 100-200W for 2-5 minutes, causing hydrophilic polar groups to be generated on the inner wall of the micro-pits.

[0023] Compared with existing technologies, the technical solution of this invention constructs a three-level synergistic self-lubricating system of "solid-liquid-film" through solid lubricant in the porous sintered rope core, liquid or semi-solid lubricant in the micro-pits on the steel wire surface, and diamond-like carbon / molybdenum disulfide composite film on the outer surface. Furthermore, the original pores inside the rope core serve as long-term oil storage chambers, the external micropores control the slow release rate of the solid lubricant, and the microcapsules in the micro-pits rupture and release supplementary lubricant under frictional temperature rise conditions, achieving dynamic self-repairing lubrication. The entire lubrication system requires no external oil replenishment and is suitable for heavy-duty applications in high-altitude or enclosed environments such as ports, mines, tower cranes, and deep well hoists where routine maintenance is difficult.

[0024] In addition, the micro-gaps formed between the strands and between the strands and the core not only provide channels for lubricant seepage but also accommodate fine abrasive particles generated by fretting wear, preventing internal wear caused by these particles. Simultaneously, these micro-gaps facilitate airflow, promoting the dissipation of frictional heat and reducing internal temperature rise. Furthermore, this design has low modification costs and is easy to promote and apply. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the cross-sectional structure of the composite metal wire rope of the present invention.

[0026] The meanings of the labels in the attached diagram are as follows: 1-rope core, 2-strand rope, 3-outer steel wire, 31-micro-dimple, 4-micro-gap. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below with reference to specific embodiments. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0028] Unless otherwise specified, the raw materials used in the following embodiments or comparative examples are all commercially available industrial-grade products, and the equipment used is conventional equipment in the field of wire rope manufacturing or equipment that has been simply modified according to the requirements of this invention.

[0029] Example 1

[0030] This embodiment 1 provides a self-lubricating wear-resistant composite metal wire rope and its preparation method, the specific steps of which are as follows:

[0031] 1) Preparation of porous sintered metal rope core: Bronze powder with an average particle size of 50 μm was used as the matrix metal powder, and urea powder with a volume fraction of 25 ± 2% was added as a pore-forming agent. A layered stacking method was adopted: first, a mixed powder with a particle size of 80-100 μm was laid at the bottom of the mold (inner layer), then a mixed powder with a particle size of 50-70 μm was laid (middle layer), and finally a mixed powder with a particle size of 30-50 μm was laid (outer layer), with a thickness ratio of 1:1:1 for each layer. The core blank with a diameter of 6.0 mm was pressed under a pressure of 150 MPa. The blank was placed in a tube sintering furnace and sintered under an argon protective atmosphere (flow rate 2 L / min). Sintering process: the temperature was increased to 450℃ at 5℃ / min and held for 30 min to remove the pore-forming agent; then the temperature was increased to 980℃ ± 20℃ at 8℃ / min and held for 2.5 h; the furnace was then cooled to room temperature. A porous sintered bronze rope core was obtained with a porosity gradient distribution from the inside to the outside (approximately 32-35% in the inside, 25-28% in the middle, and 15-18% in the outside). The average pore size was approximately 45 μm in the inner layer and approximately 8 μm in the outer layer. The large pores inside serve as long-term oil storage chambers, while the micropores outside control the slow release rate of solid lubricant.

[0032] Preparation of solid lubricant suspension: Take 100g of molybdenum disulfide powder (average particle size 1.5μm), add 1.5±0.2% (by mass) of nano-tungsten disulfide (particle size 30-50nm), add 0.3g of sodium dodecylbenzenesulfonate surfactant, and disperse in 500mL of anhydrous ethanol. Use an ultrasonic cell disruptor (300W, 20kHz) to ultrasonically disperse for 45min, ensuring uniform adsorption of nanoparticles onto the surface of MoS2 particles.

[0033] The sintered rope core was placed in a vacuum impregnation tank and evacuated to -0.095MPa ± 0.005MPa for 30 minutes. The above-mentioned solid lubricant suspension was then injected, pressurized to 0.5MPa, and maintained for 1 hour. The pressure was released, and the rope core was removed. It was dried in an 80℃ hot air circulating oven for 4 hours, and then cured at 150℃ under a nitrogen atmosphere for 2 hours to ensure that the solid lubricant adhered firmly to the inner wall of the pores.

[0034] 2) Treatment of micro-pits on the surface of outer steel wire 3: The substrate is carbon steel wire with a diameter of 1.0 mm (tensile strength of 1770 MPa grade). First, it is subjected to conventional degreasing, pickling (immersion in 10% dilute sulfuric acid for 30 seconds) and activation treatment.

[0035] Electrodeposition: The electroplating solution consisted of 80 g / L nickel sulfate, 40 g / L nickel chloride, and 35 g / L boric acid, with a pH of 4.0 ± 0.2 and a temperature of 50℃ ± 2℃. A positive pulsed current was used, with a peak current density of 5 A / dm³. 2The frequency was 1000 Hz, the duty cycle was 20%, and the electrodeposition time was 15 min. The obtained electrodeposition layer thickness was 20-30 μm, and the surface formed micron-sized protrusions distributed in an orderly array, with a protrusion height of about 15-25 μm and a spacing of about 30-50 μm.

[0036] Roller burnishing: A cemented carbide roller (YG8, hardness HRA89) is used, with a rolling force of 100N±5N and a rolling speed of 2.0m / min, in a single pass. After roller burnishing, the electrodeposited protrusions are flattened and broken, forming randomly distributed micro-pits with a diameter of 30–70μm, a depth of 10–18μm, and a surface coverage of approximately 30±3%.

[0037] Femtosecond laser secondary processing: Using a femtosecond laser device (wavelength 800nm, pulse width 120fs, power 1.5W), grooves with a depth of 8-12μm and a width of approximately 5μm are processed on the bottom and edges of the micro-pits to form a multi-scale composite oil storage structure. The laser scanning speed is 2mm / s, and the repetition frequency is 1kHz.

[0038] Cleaning and Activation: A stepped ultrasonic cleaning process was performed sequentially: First, ultrasonic cleaning was conducted at 40°C for 10 minutes with a weakly alkaline degreasing solution (pH=9.5) containing 0.5% corrosion inhibitor (benzotriazole); second, ultrasonic cleaning was conducted at room temperature for 5 minutes with deionized water and 0.1% nonionic surfactant (TX-100); third, the cells were rinsed twice with deionized water. Subsequently, vacuum plasma activation treatment was performed: using an argon / oxygen mixed gas (flow ratio 4:1), 150W of radio frequency power, 20Pa of chamber pressure, and a treatment time of 3 minutes, hydrophilic polar groups were generated on the inner wall of the micro-pits 31. Finally, the cells were dried in an 80°C vacuum oven for 30 minutes.

[0039] Lubricant filling: Polyurea-based grease (NLGI1#) is selected. 5 wt% urea-formaldehyde resin is added to the grease to encapsulate lubricant microcapsules (wall thickness 2-3 μm, core material is PAO6 synthetic oil + 3% dialkyl dithiophosphate zinc). Vacuum coating method can be used: The outer steel wire 3 is passed through a sealed cavity containing grease. The cavity is evacuated to -0.08 MPa and held for 10 seconds to allow the grease to fully penetrate the micro-pits. Then, excess grease on the surface is removed by a scraper to ensure that the grease is only present inside the pits.

[0040] 3) Twisting: Six treated outer steel wires are twisted together around a central steel wire (also surface-treated) to form a single strand. The twist direction is right-handed alternating twist, and the twist pitch is 7.0 times the strand diameter (approximately 49mm). The twisting tension is controlled at 15±1% of the single filament breaking strength. The six strands are then twisted around the core for the final twist, with a left-handed alternating twist and a twist pitch of 7.5 times the finished rope diameter (approximately 52mm). The twisting equipment integrates a laser displacement sensor (accuracy ±0.002mm) and a capacitive gap detection module (resolution 0.001mm) to measure the distance between adjacent strands and between the strands and the core in real time. The tension of each strand of rope is independently adjusted by a servo motor (set value 120N, fluctuation range controlled within ≤±2%), and the deformation (radial extrusion adjustment range 0.05~0.15mm) is dynamically adjusted using closed-loop PID control (proportional coefficient Kp=0.8, integral time Ti=0.05s, derivative time Td=0.01s). The final micro-gap width is 0.050±0.003mm.

[0041] Running-in treatment: After twisting, the entire rope is subjected to axial pre-tension with a load of 20±1% of the measured breaking tensile force, and then run-in at a low speed of 20 r / min for 45 min. During this process, the grease in the micro-dimples seeps evenly to the surface of the micro-gap under the action of compression and centrifugation; the solid lubricant in the pores of the rope core is partially transferred to the micro-gap and inter-strand contact surface under the action of fretting friction of the steel wire, together forming an initial self-lubricating layer.

[0042] 4) Depositing a composite film on the outer surface of the finished product: Using plasma-enhanced chemical vapor deposition (PECVD) equipment, with methane and hydrogen as precursors at a flow ratio of 1:4, a deposition temperature of 150℃ (low temperature, to avoid damaging the internal lubricant), an RF power of 150W, and a deposition time of 20min, a diamond-like carbon film with a thickness of 1.0±0.2μm was deposited on the outer surface of the finished wire rope. After deposition, the film hardness is approximately 15GPa. It works synergistically with the lubricant in the micro-pits 31 to reduce the coefficient of friction between the rope and the external wheel grooves and prevents the micro-gap 4 from being blocked by external dust.

[0043] Performance testing: Repeated bending tests were conducted in accordance with GB / T12347-2008 "Test Method for Bending Fatigue of Steel Wire Rope". The diameter of the bending wheel was 20 times (20d) of the nominal diameter of the steel wire rope, the tension was 10% of the minimum breaking tensile force of the steel wire rope, and the bending frequency was 60 times / min.

[0044] a. Coefficient of friction: Using a self-made friction testing machine (rope-wheel friction, linear speed 0.5 m / s, load 200 N), the average sliding friction coefficient between the rope and the cast steel wheel groove in Example 1 was measured to be 0.082 ± 0.009. In comparison, the average friction coefficient of a conventional greased steel wire rope of the same specification (6×19+FC, factory-coated with lithium-based grease) under the same conditions was 0.186 ± 0.015. The calculated reduction in friction coefficient was approximately 55 ± 6% (relative reduction rate fluctuating between 49% and 61%).

[0045] b. Bending fatigue life: Failure criterion is the occurrence of the first broken wire in the wire rope or a 15% decrease in the measured breaking force. The bending fatigue life of Example 1 is (2.7±0.3)×10 5 The lifespan of a traditional steel wire rope (of the same specifications, without self-lubricating structure) is (1.0 ± 0.1) × 10 cycles. 5 The lifetime ratio is 2.7 ± 0.4, which means it is extended by approximately 1.7 to 3.1 times.

[0046] c. Internal lubrication condition assessment: After the fatigue test, the wire rope was disassembled and the surfaces between the strands and the core were observed. In Example 1, uniformly distributed lubricant residue was still visible between the strands and on the core surface, and some grease was still not squeezed out in the micro-pits; the conventional wire rope showed obvious dry friction inside, with visible wear debris accumulation and local rust spots.

[0047] d. Micro-gap chip removal capability: In a dusty environment (with the addition of 200-mesh quartz powder, concentration 5g / m³), 3 After 500 hours of operation, disassembly and inspection revealed that although there were a small amount of wear debris and dust in the micro-gap, it did not cause blockage. The gap between the sections could still be measured at 0.02 to 0.05 mm, indicating good heat dissipation. The surface temperature measured by the infrared thermal imager was 8 to 12°C lower than that of the traditional structure.

[0048] Example 2

[0049] This embodiment 2 provides a self-lubricating wear-resistant composite metal wire rope and its preparation method, which is basically the same as that in embodiment 1, except that:

[0050] Rope core material and process: Iron-based alloy powder (Fe-2Cu-0.5C, particle size 45-75μm) is used. The pore-forming agent is ammonium bicarbonate, with a volume fraction of 30±2%. The sintering temperature is 1050℃±10℃, with a holding time of 3 hours. The porosity is 35-38% in the inner layer and 20-22% in the outer layer. Tungsten disulfide is used as the solid lubricant. A composite of graphene nanoparticles with a mass fraction of 2.0% was prepared, with polyvinylpyrrolidone (PVP) as the surfactant, and ultrasonically dispersed for 60 min.

[0051] Micro-pit parameters: Electrodeposition frequency 500Hz, duty cycle 30%, current density 8A / dm², electrodeposition time 10min, coating thickness 15–20μm. Rolling pressure 150±5N, rolling speed 1.0m / min. Micro-pit diameter 20–80μm, depth 8–15μm, area coverage 25±2%. Femtosecond laser processing groove depth 5–8μm.

[0052] Lubricant: Perfluoropolyether grease (PFPE, NLGI0#) is used, and 0.5% nano molybdenum disulfide solid powder is added to the microcapsule core material.

[0053] Micro-gap: set width 0.035±0.002mm.

[0054] Surface thin film: Molybdenum disulfide composite film (Mo(CO)6 and H2S as sources) was deposited by PECVD with a thickness of 0.6±0.1μm.

[0055] Performance test results: The coefficient of friction is 0.095±0.010, which is 49±7% lower than the coefficient of friction of traditional steel wire rope (0.186±0.015); the bending fatigue life is (2.3±0.3)×10 5 The next cycle consists of 10 traditional steel wire ropes (1.0±0.1) × 10. 5 The strength was 2.3 ± 0.4 times that of the previous one; after 200 hours of continuous operation under high load (breaking tensile force 25%), there was no obvious peeling of the solid lubricant in the rope core, and the grease retention rate in the micro-pits was about 60-70%.

[0056] Comparative Example 1: Traditional Structure

[0057] It uses commercially available 6×19+FC structure steel wire rope with a diameter of 6mm, fiber core, and is impregnated with lithium-based grease before leaving the factory.

[0058] Performance test results: coefficient of friction 0.186±0.015, bending fatigue life (1.0±0.1)×10 5 After disassembly, there was severe dry friction between the internal sections, with a large amount of wear debris. Pitting and fretting wear pits appeared on the surface of some steel wires.

[0059] Comparative Example 2: Only the rope core is self-lubricated, with no micro-pits or thin films.

[0060] The core rope 1 is the same as in Example 1, but the outer steel wire 3 is only coated with conventional grease.

[0061] Performance test results: Initial stage (first 200 hours) friction coefficient 0.11±0.02, lifespan (1.4±0.2)×10 5However, after 500 hours of operation, the release rate of the solid lubricant in the rope core was too fast, resulting in an oil-deficient zone inside, and the coefficient of friction rose to 0.16±0.03 in the later stages. This indicates that the self-lubricating effect of a single rope core is difficult to maintain in the long term.

[0062] Comparative Example 3: Has micro-dimples but lacks core self-lubrication and a thin film.

[0063] The outer steel wire 3 is the same as in Example 1, but the rope core uses a common fiber core.

[0064] Performance test results: Initial friction coefficient was 0.10±0.02, but after 300 hours of operation, the grease in the micro-pits was completely consumed, and with no subsequent replenishment, the friction coefficient gradually increased to 0.17±0.03, and the lifespan was (1.3±0.2)×10. 5 This demonstrates that the limited oil storage in the outer layer alone cannot provide long-term self-lubrication.

[0065] The test results of the above embodiments and comparative examples confirm that the present invention achieves the maintenance-free, long-lasting self-lubricating and wear-resistant properties of the rope body through the synergistic effect of the rope core self-lubrication, oil storage in the micro-dimples on the steel wire surface, chip removal and heat dissipation in the micro-gap, and the outer surface protective film. In addition, the present invention has good process compatibility, and its preparation process can be realized on the basis of traditional steel wire rope production lines: porous sintering can be carried out using existing powder metallurgy sintering furnaces (temperature 800-1100℃), which is separated from the wire drawing and twisting processes of the steel wire rope production line and does not affect the original cycle time; after the steel wire is drawn, electrodeposition and rolling are performed, which can be modified on existing galvanizing or phosphating production lines (e.g., by adding electroplating tanks and rolling devices), and the wire feeding speed can be matched with the subsequent twisting (0.5-5 m / min); only a laser displacement sensor, a capacitive gap detection module, and a servo tension control system need to be added to the twisting equipment, and the existing twisting die does not need to be replaced. The post-deformation amount is achieved by adjusting the position of the pressure die through PID; PECVD can be carried out online or offline, with a deposition rate of about 2-5 m / min, and can be integrated into the final surface treatment process of the finished rope. Moreover, in practical applications, the parameters can be optimized and adjusted according to specific working conditions and cost requirements.

[0066] The technical solution, working process, and implementation effects of the present invention have been described in detail above. It should be noted that the described examples are only typical examples of the present invention. In addition, the present invention may have many other specific implementation methods. All technical solutions formed by equivalent substitution or equivalent transformation fall within the scope of protection claimed by the present invention.

Claims

1. A self-lubricating, wear-resistant composite metal wire rope, characterized in that: The system includes a core (1) and at least one layer of strands (2) twisted around the core. The strands (2) are formed by twisting multiple outer steel wires (3). The core (1) is made of porous sintered metal material, and its pores are impregnated with solid lubricant. The surface of the outer steel wires (3) is formed with multiple micro-pits (31) by a composite process of electrodeposition and rolling. The micro-pits (31) contain liquid or semi-solid lubricant. Micro-gap (4) is provided between two adjacent strands (2) and between the strands (2) and the core (1). The width of the micro-gap (4) is 0.03 to 0.08 mm.

2. The self-lubricating wear-resistant composite metal wire rope according to claim 1, characterized in that: The porous sintered metal material is sintered bronze, sintered iron-based alloy or sintered stainless steel, with a porosity of 15-35% and an average pore size of 5-50 μm.

3. The self-lubricating wear-resistant composite metal wire rope according to claim 1, characterized in that: The solid lubricant is at least one or more of molybdenum disulfide, tungsten disulfide, graphite, and polytetrafluoroethylene.

4. The self-lubricating wear-resistant composite metal wire rope according to claim 1, characterized in that: The diameter of the micro-pits (31) is 10-100 μm and the depth is 5-30 μm, and their area coverage is 15-40% of the surface area of ​​the outer steel wire (3).

5. The self-lubricating wear-resistant composite metal wire rope according to claim 1, characterized in that: The twisting direction of the strand (2) is right-hand cross-twist or left-hand cross-twist, and the twist pitch is 6 to 8 times the diameter of the strand.

6. A method for preparing the self-lubricating wear-resistant composite metal wire rope according to any one of claims 1 to 5, characterized in that, Includes the following steps: Step S1, preparing a porous sintered metal rope core (1): metal powder and pore-forming agent are layered and stacked in a gradient from inner to outer layer with gradually decreasing particle size, pressed into a rope core blank, and sintered under a protective atmosphere to obtain a porous sintered metal rope core (1) with decreasing porosity from the inside to the outside. Solid lubricant powder is mixed with nano-tungsten disulfide or nano-graphene accounting for 0.5 to 3% of the mass fraction of the solid lubricant powder, surfactant is added and ultrasonic dispersion is performed, and then the treated mixed powder is dispersed in a solvent to form a suspension. Solid lubricant is filled into the pores of the rope core (1) by vacuum impregnation or pressure impregnation, and then dried and cured. Step S2, surface micro-pit (31) treatment of outer steel wire: Place the outer steel wire (3) to be treated in the electrodeposition tank, and form an electrodeposition layer with micron-level protrusions on the surface of the outer steel wire (3) by electrodeposition method. During electrodeposition, a positive pulse current is used with a frequency of 500-2000Hz and a duty cycle of 10-30%. Then, a rolling tool is used to roll the surface of the outer steel wire (3) to flatten the protrusions in the electrodeposition layer and form randomly distributed micro-pits (31). A femtosecond laser is used to process grooves or textures with a depth of 5-15μm at the bottom and edge of the micro-pits (31) to form a multi-scale composite oil storage structure. Liquid or semi-solid lubricant is filled into each micro-pit (31). The liquid / semi-solid lubricant contains microcapsules with self-healing function. Step S3, Twisting and Micro-gap Control: The multiple outer steel wires (3) processed in step S2 are twisted into strands (2), and the twisting tension and pitch of each strand (2) are controlled; then, the multiple strands (2) are twisted around the rope core obtained in step S1. A laser displacement sensor and a capacitive gap detection module are integrated in the twisting equipment to measure the distance between the strands and between the strands (2) and the rope core (1) in real time; the tension and radial compression of each strand are independently adjusted by a servo motor, and the deformation is dynamically adjusted by a closed-loop PID algorithm to ensure that the distance between adjacent strands (2) and between the strands (2) and the rope core (1) is controlled. Micro gaps (4) with a width of 0.03 to 0.08 mm are formed between the wires, with a width deviation of ≤ ±0.005 mm, to obtain the finished metal wire rope. After twisting, the metal wire rope is subjected to axial pre-tension, with a load of 15 to 25% of the breaking tensile force, and is run-in at a low speed of 10 to 30 r / min for 30 to 60 min. This allows the liquid or semi-solid lubricant in the micro-pits (31) to seep out evenly to the surface of the micro gaps (4), while the solid lubricant in the pores of the rope core (1) is partially transferred to the surface of the micro gaps (4) under friction, thus forming an initial self-lubricating layer. Step S4: After obtaining the twisted and run-in metal wire rope in step S3, a diamond-like carbon or molybdenum disulfide composite film with a thickness of 0.5 to 2 μm is deposited on the outer surface of the wire rope using plasma-enhanced chemical vapor deposition.

7. The method according to claim 6, characterized in that, In step S1: the pore-forming agent is urea, ammonium bicarbonate or sodium chloride, and its addition amount is 15-35% of the volume of the metal powder; the sintering temperature is 800-1100℃, and the sintering time is 1-4h.

8. The method according to claim 6, characterized in that, In step S2: the rolling process uses a carbide roller, the rolling force is 50-200N, and the rolling speed is 0.5-5m / min.

9. The method according to claim 6, characterized in that, Between step S2 and step S3: the outer steel wire (3) with micro-pits (31) on the surface is subjected to step-by-step ultrasonic cleaning, vacuum plasma activation treatment and vacuum drying treatment in sequence. The step-by-step cleaning includes cleaning with weak alkaline degreasing solution and cleaning with deionized water and non-ionic surfactant. The vacuum plasma activation treatment uses argon / oxygen mixed gas, radio frequency power of 100-200W and time of 2-5min, so that hydrophilic polar groups are generated on the inner wall of the micro-pits (31).

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