Non-conductive self-lubricating bearing conductive integrated molding process

Abstract

This invention discloses an integrated molding process for conductive bearings that are non-conductive and self-lubricating, belonging to the field of sliding bearing manufacturing technology. The invention uses a composite strip with a conductive metal mesh as the metal base and PTFE composite material as the lubricating layer as the substrate. Integrated molding is achieved through a six-station progressive die. First, 2-3 protrusions are stamped on the strip. Then, the stamping pressure drives a 30°-45° wedge mechanism to scrape the lubricating layer from the protrusion surface at a fixed depth. The finished product is obtained through slicing, rolling, extrusion shaping, and stamping flanging. A detachable scraper and pore design optimize the processing flow. This invention achieves automated one-step molding of conductive bearings from strip to finished product, significantly improving production efficiency. The manufactured bearings have low contact resistance and a stable coefficient of friction. After electrophoretic coating, the salt spray test duration exceeds 96 hours, and the product consistency and structural stability are significantly better than traditional processes.

Description

Technical Field

[0001] This invention belongs to the field of sliding bearing manufacturing technology, specifically a conductive integrated molding process for non-conductive self-lubricating bearings. Background Technology

[0002] Sliding bearings are core transmission components in automobiles, industrial equipment, and home appliances. They need to possess both low-friction self-lubricating properties and stable electrical conductivity. Especially in the automotive exterior parts sector, the bearing surface must meet the requirements of electrophoretic coating to achieve corrosion protection, and conductivity is key to ensuring the uniformity of the electrophoretic coating. Traditional manufacturing processes require secondary stamping of bosses and machining (turning and milling) after bearing forming to remove surface lubricating material, exposing the internal metal substrate to achieve conductivity. This process suffers from time-consuming and labor-intensive secondary processing, low production efficiency, and poor product consistency, and can no longer meet the needs of industrial mass production.

[0003] Existing technologies have made improvements to the preparation of conductive self-lubricating bearings. For example, invention patent CN120444333B discloses a conductive self-lubricating bearing based on a metal mesh extension structure and its preparation method. By punching through holes, a high-ductility copper alloy mesh is extended to the non-conductive surface to form a conductive path, eliminating the need for secondary processing. However, this process focuses on the punching structure design of the bearing body and adopts a single-process manufacturing mode, leaving room for improvement in production efficiency. Furthermore, the through-hole structure can easily reduce the bearing's load-bearing capacity. Invention patent CN108891103B discloses a conductive self-lubricating composite plate for bearings and its preparation method. Conductivity is achieved by combining a metal base layer recessed structure with a conductive self-lubricating film. This process focuses on the material formulation and composite process of the substrate, only completing the preparation of the basic bearing substrate. Multiple subsequent processing steps are still required to produce the finished product, resulting in a relatively long overall processing flow.

[0004] While the aforementioned existing technologies have all abandoned traditional secondary processing techniques and achieved one-time fabrication of conductive structures, they have not solved the problem of fully automated, integrated molding of bearings from substrate to finished product. They either focus on processing a single structure or only complete substrate preparation. This invention addresses the shortcomings of existing technologies by designing a six-station progressive die and a wedge-shaped shovel linkage structure. This enables fully automated, one-time molding of metal mesh-based self-lubricating conductive bearings from raw material to finished product. While ensuring conductivity and self-lubrication performance, it significantly improves production efficiency. Furthermore, through the design of a convex-hull fixed-point conductive structure, it balances the conductivity and structural load-bearing capacity of the bearing, making it more suitable for the actual needs of large-scale industrial production compared to existing technologies. Summary of the Invention

[0005] (a) Purpose of the invention The purpose of this invention is to provide an integrated conductive forming process for non-conductive self-lubricating bearings, solving the technical problems of fragmented processing steps, multiple coordination processes, low production efficiency, and poor product consistency in existing conductive self-lubricating bearing manufacturing processes. It also addresses the difficulty in balancing conductive structure design with bearing load-bearing capacity in existing processes. This invention utilizes a six-station progressive die and a wedge-shaped scraper linkage design to achieve automated integrated forming of the bearing from material to finished product. It precisely controls the exposed conductive structure of the metal substrate, ensuring low friction, high conductivity, and compatibility with electrophoretic coating while improving production efficiency and product quality stability, reducing overall manufacturing costs, and providing a feasible technical solution for industrialized mass production.

[0006] (II) Complete Technical Solution The present invention discloses a method for preparing a metal mesh-based self-lubricating conductive bearing. Using a composite strip with tin bronze alloy woven mesh as the metal base and PTFE composite material as the lubricating layer as the substrate, a high-speed progressive forming machine combined with a six-station progressive die achieves fully automated integrated forming. First, at the first station, 2-3 controllable circular protrusions are formed by stamping at 8MPa-15MPa. Then, at the second station, the stamping pressure drives a 30°-45° inclined wedge mechanism, which in turn drives a separable scraper to scrape the top of the protrusions to a fixed depth of 0.1mm-0.3mm, exposing the metal substrate and forming a boss. This station is equipped with vacuum holes for waste material adsorption. After scraping, burrs are removed by a brush roller. Next, at the third station, the strip is cut into individual sheet blanks. At the fourth station, it is rolled into a cylindrical shape at 60℃-80℃. At the fifth station, it is extruded and shaped to ensure dimensional accuracy. At the sixth station, it is stamped and flanged to form the finished product. Finally, the product is obtained after ultrasonic cleaning with anhydrous ethanol and hot air drying. Throughout the entire process, each station of the progressive die operates synchronously, the material belt is driven by a synchronous belt, the processing cycle of a single finished product is ≤8s, and the production efficiency can reach 8000 pieces / h-9000 pieces / h. Furthermore, the detachable scraper design reduces tool maintenance costs, and the pore structure avoids waste residue.

[0007] To achieve the above objectives, this invention discloses a non-conductive self-lubricating bearing integrated conductive molding process. Using a metal-based lubricating layer composite strip as the substrate, integrated continuous molding is achieved through a six-station progressive die, comprising the following steps: S1. Convex stamping: The composite strip is conveyed to the first station of the progressive die, and 2-3 circular convex bulges are formed at the preset position of the strip using a stamping head. The height of the convex bulges is 0.3mm-0.8mm, the diameter is 1.5mm-3.0mm, the center distance between adjacent convex bulges is 5mm-10mm, the stamping pressure is 8MPa-15MPa, and the stamping speed is 50mm / s-80mm / s. S2. Lubricating layer scraping: The stamped strip with the convex bump is conveyed to the second station of the progressive die. The stamping pressure drives the inclined wedge mechanism with an inclination angle of 30°-45°, which drives the scraper to scrape the top of the convex bump to a fixed depth, so that the lubricating layer at the top of the convex bump is removed to form a boss with exposed metal base. The scraping depth is 0.1mm-0.3mm. After scraping, the exposed area of ​​the metal base accounts for more than 95% of the area of ​​the top of the convex bump. The cutting edge angle of the scraper is 20°-30°. S3. Slicing and cutting: The scraped strip is conveyed to the third station of the progressive die, where the strip is sliced ​​into individual sheet blanks. The slicing speed is 40mm / s-60mm / s, and the cutting tolerance is ±0.05mm. S4. Rolling: The sheet blank is conveyed to the fourth station of the progressive die, and the blank is rolled into a hollow cylinder by the rolling die. The diameter of the mandrel of the rolling die is the nominal inner diameter of the bearing, and the rolling pressure is 5MPa-10MPa. S5. Extrusion and shaping: The cylindrical blank is conveyed to the fifth station of the progressive die and extruded and shaped using a shaping die. After shaping, the inner diameter tolerance of the bearing is ±0.02mm and the outer diameter tolerance is ±0.03mm. The shaping pressure is 6MPa-12MPa. S6. Stamping and Flanging: The shaped blank is conveyed to the sixth station of the progressive die, and the stamping and flanging is completed by using a flanging die. The flanging height is 1.0mm-2.0mm, the flanging angle is 90°±1°, and the stamping and flanging pressure is 7MPa-14MPa, to obtain the finished metal mesh-based self-lubricating conductive bearing.

[0008] Preferably, the composite strip is composed of a conductive metal mesh base and a PTFE composite material lubricating layer. The conductive metal mesh is selected from at least one of copper alloy woven mesh, copper alloy punched mesh, aluminum-coated steel punched mesh, or aluminum alloy punched mesh. The diameter of the conductive metal mesh wires is 0.1mm-0.2mm, the mesh size is 0.5mm×0.5mm-1.0mm×1.0mm, and the thickness is 0.2mm-0.4mm. The coating thickness of the PTFE composite material lubricating layer is 0.1mm-0.3mm, and the total thickness of the composite strip is 0.3mm-0.7mm.

[0009] Preferably, the wedge mechanism in step S2 is equipped with a detachable scraper. The scraper and the wedge mechanism are connected by a slot, with a slot clearance of 0.01mm-0.02mm, and the scraper replacement time is ≤5min. This invention removes the lubricating layer from the top of the convex bulge using not only scraping with a scraper but also milling. See the detailed structure for details. Figure 3 The principle is similar to scraping with a spatula, except that the method of removing the lubricating layer at the top of the protrusion has been changed.

[0010] Preferably, the second and third stations of the progressive die are provided with pore structures, the pore diameter is 0.8mm-1.2mm, the number of pores is 2-4 per station, and the vacuum degree inside the pores is -0.06MPa~-0.09MPa, which are used to adsorb the lubricating waste generated by scraping.

[0011] Preferably, after scraping in step S2, the exposed metal substrate of the convex bulge is deburred by a brush roller. The brush roller rotates at a speed of 300 r / min to 500 r / min and the contact pressure with the material strip is 0.5 MPa to 1.0 MPa.

[0012] Preferably, the material conveying between each station of the six-station progressive die adopts synchronous belt drive, with a conveying speed of 30mm / s-50mm / s, and the processing cycle of each station is synchronized, with a single finished product processing cycle of ≤8s.

[0013] Preferably, the copper alloy woven mesh is a tin bronze alloy mesh with a tin content of 5wt%-8wt% and a copper content of 92wt%-95wt%, and the weaving method is plain weave; the PTFE composite material lubricating layer is made of 10wt%-20wt% glass fiber, 3wt%-5wt% molybdenum disulfide and the balance PTFE (the total mass fraction is 100%, for example, 10wt% glass fiber, 5wt% molybdenum disulfide, and 85wt% PTFE).

[0014] Preferably, in the rolling process of step S4, the rolling temperature of the blank is 60℃-80℃, and hot air heating is used with a heating wind speed of 2m / s-4m / s.

[0015] Preferably, after the stamping and flanging in step S6 is completed, the finished bearing is cleaned and dried. The cleaning is carried out using hydrocarbon cleaning for 2-5 minutes, and the drying is carried out using hot air drying at a temperature of 80℃-100℃ for 10-15 minutes.

[0016] (III) Core Innovation Points This invention innovatively designs a six-station progressive die integrated molding process, combining six processes—convex stamping, lubricant layer scraping, slicing, rolling, extrusion shaping, and stamping flanging—into a single progressive die. This achieves continuous and automated processing from composite material to finished bearing, eliminating the fragmented processing methods of existing technologies. Each station achieves synchronized processing cycles via synchronous belt drives, with a single-piece processing cycle of ≤8s, significantly improving production efficiency. Furthermore, the fully automated processing reduces manual intervention, effectively ensuring the consistency of product dimensions and performance.

[0017] This invention innovatively employs a wedge-shaped scraper linkage structure driven by stamping pressure. The downward pressure from the stamping of the convex hull directly drives a 30°-45° inclined wedge mechanism, initiating scraper movement. This reuses the stamping pressure, eliminating the need for an additional power source to drive the cutting mechanism and simplifying the equipment structure. Simultaneously, by precisely controlling the wedge angle, scraper cutting edge angle, and scraping depth, it achieves accurate removal of the lubricating layer from the convex hull surface at a fixed depth and position, ensuring that the exposed metal substrate area accounts for ≥95%. Compared to existing stamping-extended conductive structures, this invention offers higher precision in conductive contact fabrication and more stable conductivity.

[0018] This invention innovatively designs a convex-shaped fixed-point conductive structure. By stamping 2-3 circular convex bulges at preset positions on the material strip and removing the lubricating layer only at the top of the convex bulges, fixed-point conductive contacts are formed. This ensures effective contact between the rotating shaft and the metal substrate to meet the conductivity requirements, while avoiding the need to open through holes or remove large areas of the lubricating layer on the bearing body. It effectively preserves the structural integrity of the bearing, balances conductivity and bearing load-bearing capacity, and resolves the contradiction between conductive structure design and structural strength in existing technologies.

[0019] This invention addresses the practical pain points of industrial production by designing a detachable scraper and vacuum hole structure. The scraper and wedge mechanism are connected by a slot, with a replacement time of ≤5 minutes, significantly reducing tool maintenance costs and equipment downtime. The vacuum holes in the second and third stations can quickly absorb the lubricating waste generated during scraping, preventing waste residue from remaining on the mold or product surface, ensuring the continuity of the processing flow and the surface quality of the product. Compared with existing technologies, this invention is more in line with the needs of large-scale industrial production.

[0020] (iv) Related mechanisms The core mechanism of this invention is mainly reflected in the precise control of force transmission and material removal during machining, as well as the coordinated matching of the conductive structure and the bearing structure. In the wedge scraper linkage structure, the stamping pressure is converted into a horizontal cutting force through the inclined surface of the wedge mechanism. When the wedge angle is set to 30°-45°, the force transmission efficiency is the highest, and the problems of excessive cutting force due to too small an angle and insufficient scraping stroke due to too large an angle can be avoided. Combined with a scraper cutting edge angle of 20°-30°, the lubricating layer is removed by shearing, reducing damage to the metal substrate.

[0021] Regarding the fixed-point conductivity mechanism of the convex hull, by controlling the height, diameter, and spacing of the convex hull, the exposed metal substrate can achieve surface contact with the shaft after bearing assembly. Compared with line contact or point contact, this effectively reduces contact resistance and improves conductivity stability. At the same time, the fixed-point convex hull structure removes the lubricating layer only in local areas, while the lubricating layer in the remaining areas of the bearing inner wall is completely preserved, ensuring the low friction characteristics of the bearing and not damaging the overall structure of the metal mesh base. The bearing's load-bearing capacity and vibration resistance performance are not affected.

[0022] Regarding the continuous processing mechanism of progressive dies, the processing parameters and conveying speed of each station are precisely matched, enabling the material strip to complete continuous processing during the conveying process. This avoids positioning errors in multi-process processing and ensures the dimensional accuracy of the product. The vacuum holes adsorb waste material through negative pressure. The design of the hole diameter and vacuum degree parameters enables the rapid adsorption and collection of waste material, avoiding the accumulation of waste material in the die, which would lead to a decrease in processing accuracy and product defects.

[0023] Beneficial technical effects 1. Reduce costs and increase efficiency.

[0024] This invention utilizes an integrated continuous forming process with a six-station progressive die to automate the processing of bearings from raw material to finished product. The processing cycle for a single finished product is ≤8 seconds, and the production efficiency reaches 8000-9000 pieces / hour. The detachable scraper design reduces tool maintenance costs, and the vacuum hole structure reduces labor costs for waste removal, resulting in significant industrial economic benefits.

[0025] 2. All aspects of the product's performance have been improved.

[0026] The metal mesh-based self-lubricating conductive bearing prepared by this invention has an exposed metal substrate area of ​​≥95% at the bulge, a contact resistance of ≤50mΩ, and stable conductivity. The bearing's inner wall lubrication layer is completely preserved, with a friction coefficient stable at 0.08-0.12, demonstrating excellent self-lubricating performance. Fully automated processing effectively avoids errors from manual operation, resulting in an inner diameter tolerance of ±0.02mm and an outer diameter tolerance of ±0.03mm, significantly improving product dimensional consistency and reducing the defect rate to below 0.5%.

[0027] 3. Stable structure and strong adaptability to process.

[0028] The convex-hull fixed-point conductive structure design of this invention maintains the structural integrity of the bearing while ensuring conductivity. The bearing's load-bearing capacity is improved compared to bearings with through-hole conductive structures, and it exhibits excellent vibration resistance, making it suitable for complex operating conditions such as bumpy rides during vehicle operation. The prepared bearing has a high surface flatness, meeting the requirements of electrophoretic coating processes. After electrophoretic coating, it withstands over 96 hours of salt spray testing, demonstrating excellent corrosion resistance. Furthermore, this invention is directly based on existing composite strip processing, eliminating the need to change raw materials. Enterprises only need to modify the mold to upgrade the process, resulting in low-cost and highly adaptable process modifications. Attached Figure Description

[0029] Figure 1 This is a flowchart of the integrated conductive molding process for the non-conductive self-lubricating bearing of the present invention. Figure 2 This is a schematic diagram of the connection structure between the separable shovel and the wedge mechanism of the present invention.

[0030] Figure 3This is a schematic diagram of the connection structure of the milling cutter, slicer, and boss described in this invention.

[0031] The names of the components shown in the diagram are as follows: Figure 2 In the diagram, 201—slice, 202—wedge, 203—shovel, 204—protrusion. Detailed Implementation

[0032] Before further describing specific embodiments of the present invention, it should be understood that the scope of protection of the present invention is not limited to the specific embodiments described below; it should also be understood that the terminology used in the embodiments of the present invention is for describing specific embodiments and not for limiting the scope of protection of the present invention. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers.

[0033] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this invention, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as commonly understood by those skilled in the art. In addition to the specific methods, apparatus, and materials used in the embodiments, based on the knowledge of those skilled in the art and the description of this invention, any prior art methods, apparatus, and materials similar to or identical to those described in the embodiments of this invention may be used to implement this invention.

[0034] Unless otherwise stated, the test methods, detection methods and preparation methods disclosed in this invention all adopt conventional techniques in this technical field.

[0035] (I) The role and source of reagents and equipment The composite strip used in this invention is composed of a tin bronze alloy woven mesh and a PTFE composite material lubricating layer. The tin bronze alloy mesh serves as a conductive metal substrate and provides structural strength to the bearing. The PTFE composite material lubricating layer provides the bearing with low-friction self-lubricating properties. Anhydrous ethanol is used as a cleaning agent to remove machining debris and oil stains from the surface of the finished bearing, ensuring the cleanliness of the product surface.

[0036] The tin bronze alloy woven mesh used in this invention is commercially available, with specifications of 0.1-0.2 mm wire diameter and 0.5-1.0 mm × 0.5-1.0 mm mesh size; the PTFE composite material lubricating layer raw material is purchased from Shanghai Maclean Biochemical Technology Co., Ltd., and PTFE, glass fiber, and molybdenum disulfide are all industrial grade; anhydrous ethanol is purchased from Sinopharm Chemical Reagent Co., Ltd., and is of analytical grade.

[0037] The high-speed progressive molding machine, six-station progressive die, wedge scraper linkage structure, separable scraper, ultrasonic cleaner, hot air drying oven, brush roller, etc. used in this invention are all commercially available standard models.

[0038] Example 1 The composite strip (total thickness 0.3 mm) is prepared using a high-speed progressive forming machine, with tin bronze alloy woven mesh (metal wire diameter 0.1 mm, mesh size 0.5 mm × 0.5 mm, thickness 0.2 mm) and PTFE composite lubricating layer (PTFE 75 wt%, glass fiber 20 wt%, molybdenum disulfide 5 wt%, coating thickness 0.1 mm) as the base material. S1 convex stamping: Stamping pressure 8MPa, stamping speed 50mm / s, stamping 2 convex bulges, height 0.3mm, diameter 1.5mm, spacing 5mm; S2 lubricating layer scraping: wedge 202 angle 30°, scraper 203 cutting edge angle 20°, scraping depth 0.1mm, air The vacuum degree is -0.06MPa, the brush roller speed is 300r / min, the contact pressure is 0.5MPa, and the lubricating layer on the top of the protrusion is removed by scraping to form the protrusion 204 with exposed metal substrate; S3 Slicing and cutting: the slicing speed of slicing 201 is 40mm / s; S4 Rolling and forming: rolling pressure 5MPa, temperature 60℃, heating air speed 2m / s; S5 Extrusion shaping: shaping pressure 6MPa, inner diameter tolerance ±0.02mm, outer diameter tolerance ±0.03mm; S6 Stamping and flanging: flanging height 1.0mm, flanging angle 90°, pressure 7MPa. Finally, the finished product is obtained by hydrocarbon cleaning for 2min and hot air drying at 80℃ for 10min. The equipment production efficiency is 8200 pieces / h, and the single piece processing cycle is 8s.

[0039] Example 2 The composite strip (total thickness 0.5 mm) is prepared using a high-speed progressive forming machine, with tin bronze alloy woven mesh (metal wire diameter 0.15 mm, mesh size 0.75 mm × 0.75 mm, thickness 0.3 mm) and PTFE composite material lubricating layer (PTFE 81 wt%, glass fiber 15 wt%, molybdenum disulfide 4 wt%, coating thickness 0.2 mm) as the base material. S1 convex stamping: Stamping pressure 12MPa, stamping speed 65mm / s, stamping 3 convex bulges, height 0.5mm, diameter 2.2mm, spacing 7.5mm; S2 lubricating layer scraping: wedge 202 angle 37°, scraper 203 cutting edge angle 25°, scraping (when the stamping head of the first station goes down to stamp the convex bulge, its downward pressure is transmitted through the connecting rod or the mechanical transmission structure of the mold itself, driving the wedge (202) of the second station to move in the horizontal direction, thereby driving the scraper (203) connected to its slot to scrape the top of the stamped convex bulge) depth 0.2mm, air hole true The process involves several steps: S1 - 0.075 MPa, 400 r / min brush roller speed, 0.75 MPa contact pressure, scraping to remove the lubricating layer from the top of the protrusion, forming a bare metal substrate protrusion 204; S3 - slicing: slicing speed 201 50 mm / s; S4 - rolling: rolling pressure 7.5 MPa, temperature 70℃, heating air velocity 3 m / s; S5 - extrusion shaping: shaping pressure 9 MPa, inner diameter tolerance ±0.02 mm, outer diameter tolerance ±0.03 mm; S6 - stamping and flanging: flanging height 1.5 mm, flanging angle 90°, pressure 10.5 MPa. Finally, the finished product is obtained after hydrocarbon cleaning for 3.5 min and hot air drying at 90℃ for 12.5 min. The equipment has a production efficiency of 8650 pieces / h and a single-piece processing cycle of 6 s.

[0040] Example 3 The composite strip (total thickness 0.7 mm) is prepared using a high-speed progressive forming machine, with tin bronze alloy woven mesh (metal wire diameter 0.2 mm, mesh size 1.0 mm × 1.0 mm, thickness 0.4 mm) and PTFE composite lubricating layer (PTFE 85 wt%, glass fiber 10 wt%, molybdenum disulfide 5 wt%, coating thickness 0.3 mm) as the base material. S1 convex stamping: Stamping pressure 15MPa, stamping speed 80mm / s, stamping 2 convex bulges, height 0.8mm, diameter 3.0mm, spacing 10mm; S2 lubricating layer scraping: wedge 202 angle 45°, scraper 203 cutting edge angle 30°, scraping depth (when the stamping head of the first station goes down to stamp the convex bulge, its downward pressure is transmitted through the connecting rod or the mechanical transmission structure of the mold itself, driving the wedge (202) of the second station to move in the horizontal direction, thereby driving the scraper (203) connected to its slot to scrape the top of the stamped convex bulge 0.3mm, air hole vacuum degree -0.09MPa, brush roller speed 500r / min, The contact pressure is 1.0 MPa. Scraping removes the lubricating layer from the top of the raised bulge, forming a bare metal substrate, boss 204. S3: Slicing and cutting: Slice 201 cuts at 60 mm / s. S4: Rolling and forming: Rolling pressure 10 MPa, temperature 80℃, heating air velocity 4 m / s. S5: Extrusion shaping: Shaping pressure 12 MPa, inner diameter tolerance ±0.02 mm, outer diameter tolerance ±0.03 mm. S6: Stamping and flanging: Flanging height 2.0 mm, flanging angle 90°, pressure 14 MPa. Finally, after hydrocarbon cleaning for 5 minutes and hot air drying at 100℃ for 15 minutes, the finished product is obtained. The equipment has a production efficiency of 9000 pieces / hour and a single-piece processing cycle of 4 seconds.

[0041] Comparative Example 1 The traditional secondary processing technique is adopted: first, the composite strip is stamped, rolled, shaped, and flanged to obtain the bearing blank, then a convex bulge is formed by secondary stamping, and finally the lubricating layer on the surface of the convex bulge is removed by milling. The remaining raw materials are the same as in Example 2. The milling speed is 3000 r / min and the feed rate is 50 mm / min. After processing, the finished product is obtained by the same cleaning and drying process.

[0042] Comparative Example 2 The process using publication number CN120444333B is as follows: a composite body is prepared using the same copper alloy mesh and PTFE composite material as in Example 2. Through holes are punched using a punching die to form conductive paths. The punch speed is 20 mm / s and the punching gap is 30%. The finished product is then obtained by rolling and flanging. The remaining processing parameters are the same as in Example 2.

[0043] Comparative Example 3 The process of this invention is adopted, but the wedge mechanism is not set. The lubricating layer is removed directly by a fixed scraper. The other parameters are the same as in Example 2. The scraper is driven by an external cylinder with a cylinder pressure of 0.8 MPa.

[0044] Performance testing (I) Testing Process and Standards The performance of the metal mesh-based self-lubricating conductive bearings prepared in Examples 1-3 and Comparative Examples 1-3 of this invention was tested. Commercially available conventional conductive self-lubricating bearings were selected as blank control samples. Test indicators included conductivity, self-lubrication, corrosion resistance after electrophoretic coating, production efficiency, and product defect rate. The test standards for each indicator are as follows: Contact resistance: According to GB / T3048.4-2025 "Test methods for electrical properties of wires and cables - Part 4: DC resistance test of conductors", the contact resistance of the convex conductive contact was measured using a DC resistance tester. Five test points were tested for each sample, and the average value was taken. Friction coefficient: According to GB / T10006-2021 "Determination of friction coefficient of plastic film and sheet", the friction coefficient between the inner wall of the bearing and the steel shaft was determined by a friction and wear tester. The test load was 50N, the rotation speed was 300r / min, and the test time was 30min. Salt spray test: According to GB / T10125-2021 "Artificial Atmosphere Corrosion Test - Salt Spray Test", the bearing was subjected to a neutral salt spray test after electrophoretic coating. The test temperature was 35℃ and the salt spray concentration was 5wt%. The time when corrosion spots appeared on the bearing surface was recorded. Production efficiency: Calculate the production efficiency per unit time by counting the number of finished products produced after the equipment has been running continuously for 2 hours. Product defect rate: Calculate the defect rate by counting the total number of finished products and the number of defective products (out of tolerance, non-conductivity, surface defects) after the equipment has been running continuously for 8 hours.

[0045] (II) Test Results Table 1. Performance test results of non-conductive self-lubricating bearings in the examples and comparative examples. Analysis of possible causes for the differences in test results in Table 1 above: In this test, the friction coefficients of Examples 1-3 were all ≤0.1, while the friction coefficients of Comparative Examples 1-3 and the blank control group were all >0.1. The differences in each indicator mainly stem from the rationality of the processing technology design, the precision of the conductive structure preparation, and the differences in the control of the integrity of the lubrication layer. The specific mechanism of the differences in each indicator is analyzed as follows: (I) Core Reasons for Differences in Friction Coefficients The friction coefficients of Examples 1-3 are significantly lower than those of the comparative examples and the blank control, and are consistently controlled within 0.1. The core reason for this is that the fixed-point convex conductive structure design and automated precision machining process of this invention achieve a dual guarantee of the integrity and surface flatness of the bearing lubrication layer. This invention removes the lubrication layer only in a very small fixed-point area of ​​the convex ...

[0046] Comparative Example 1 employs traditional two-stage milling, where the bearing blank is formed before the bulge is machined and the lubricating layer is removed. This secondary clamping and positioning easily leads to the tool scratching the lubricating layer on the inner wall of the bearing, disrupting the continuity of the lubricating film. Furthermore, the cutting force of milling easily causes micro-cracks in the lubricating layer, accelerating lubricating layer shedding during friction and increasing the coefficient of friction to 0.142. Comparative Example 2's punched through-hole conductive structure creates through-holes in the bearing body, directly disrupting the overall integrity of the lubricating layer. The lubricating layer at the edge of the through-hole is prone to chipping during punching, and the rotating shaft directly contacts the metal surface at the edge of the through-hole during rotation. The friction coefficient increased to 0.125. In Comparative Example 3, the wedge scraper linkage structure was not used. The fixed scraper driven by the external cylinder was not synchronized with the stamping cycle. During scraping, the lubricating layer around the convex bulge was easily squeezed and warped. The warped lubricating layer formed additional resistance during friction. Moreover, the uneven scraping caused surface unevenness, which would damage the lubricating film. The friction coefficient increased to 0.138. The commercially available bearing in the blank control used the traditional spraying lubricating layer process. The lubricating layer coating was uneven and the bonding force with the metal substrate was weak. The lubricating layer was easily worn during friction, and the friction coefficient was as high as 0.156.

[0047] (ii) Reasons for differences in contact resistance The contact resistance of Examples 1-3 is significantly lower than that of the comparative example and the blank control. The core reason is that the precise scraping process of the wedge-blade linkage structure of this invention achieves complete and intact exposure of the metal substrate, and the surface contact design of the convex hull greatly reduces the contact resistance. This invention achieves complete shearing removal of the lubricating layer on the convex hull surface by controlling the wedge angle (30°-45°), the blade angle (20°-30°), and the scraping depth (0.1mm-0.3mm). The exposed area of ​​the metal substrate accounts for ≥95%, and the convex hull has a circular surface structure, which forms a stable surface contact after assembly with the rotating shaft, making the current conduction path smoother. At the same time, the deburring treatment of the brush roller after scraping (300r / min-500r / min) removes the micro-burrs on the surface of the metal substrate, avoiding poor contact caused by burrs, and further reducing the contact resistance.

[0048] In Comparative Example 1, the secondary milling process is prone to incomplete removal of the lubricating layer. Wear of the milling tool leads to residual lubricating layer debris on the convex surface, forming a conductive barrier. Furthermore, the high surface roughness of the milled metal results in point contact with the rotating shaft, leading to high contact resistance. In Comparative Example 2, the punching extension conductive structure relies on the plastic extension of the metal mesh to form a conductive path. Uneven local stretching is prone to occur during the extension of the metal mesh, resulting in line contact at the conductive points. Moreover, the lubricating layer debris in the through holes is difficult to completely remove, resulting in higher contact resistance than in the example. In Comparative Example 3, the fixed scraper has uneven scraping depth due to the asynchronous power source and stamping cycle. The metal substrate in some convex areas is not fully exposed, and there is no professional deburring treatment. Surface burrs form contact resistance, resulting in high overall contact resistance. The commercially available bearing conductive structure in the blank control is a side-grooved type. The metal substrate at the groove is prone to oxidation, and the low grooving precision results in a small contact area and the highest contact resistance.

[0049] (III) Reasons for the difference in salt spray test duration In Examples 1-3, the salt spray test duration after electrophoretic coating exceeded 96 hours, and the anti-corrosion performance was significantly better than the comparative example and blank control. The core reason is that the high precision of the processing technology ensured the high flatness and dimensional consistency of the bearing surface, allowing the electrophoretic coating to adhere evenly and firmly to the bearing surface. The six-station progressive die of this invention realizes one-time forming from material to finished product. The dimensional accuracy of each process is strictly controlled (inner diameter tolerance ±0.02mm, outer diameter tolerance ±0.03mm). The bearing surface is free of processing marks, bumps, and burrs. During electrophoretic coating, the electrophoretic paint can form a uniform paint film on the surface with a thickness deviation of ≤5μm. Moreover, the paint film has a strong adhesion to the bearing surface, and paint film peeling and blistering are not likely to occur during salt spray testing. At the same time, the exposed metal substrate at the bulge is highly clean after deburring and cleaning, allowing the electrophoretic paint to form a good bond with the metal substrate, preventing corrosive media from penetrating from the conductive contacts.

[0050] The secondary processing of Comparative Example 1 resulted in milling scratches and clamping marks on the bearing surface, leading to poor surface flatness. The electrophoretic paint tended to accumulate unevenly at the scratches, resulting in significant differences in paint film thickness. During the salt spray test, weak areas of the paint film were easily penetrated by corrosive media, with a test duration of 73 hours. The through-hole structure of Comparative Example 2 caused electrophoretic paint to easily run off the hole walls, resulting in insufficient paint film thickness. Furthermore, the edge chipping of the lubricating layer at the through-hole edges led to poor paint film adhesion, allowing corrosive media to easily penetrate from the hole walls, with a test duration of 81 hours. Uneven scraping in Comparative Example 3 resulted in raised edges and debris residue on the bearing surface, preventing the electrophoretic paint from bonding tightly to the raised edges and creating gaps in the paint film, with a test duration of 77 hours. The commercially available bearing in the blank control had low surface flatness and weak adhesion between the lubricating layer and the metal substrate, resulting in poor electrophoretic paint adhesion and easy paint film peeling, with a salt spray test duration of only 48 hours.

[0051] (iv) Reasons for the difference between production efficiency and product defect rate The production efficiency of Examples 1-3 (8000-9000 pieces / h) is significantly higher than that of the comparative examples, and the product defect rate (0.2%-0.4%) is significantly lower. This is primarily due to the fully automated continuous forming process of the six-station progressive die of this invention, which fundamentally solves the efficiency bottlenecks and error problems associated with traditional processes involving multiple steps and equipment. The six-station progressive die integrates punching, lubrication layer scraping, slicing, rolling, shaping, and flanging into a single production line. Each station achieves complete synchronization of processing cycles via synchronous belt drives (conveyor speed 30mm / s-50mm / s), with a single finished product processing cycle ≤8s. No workpiece transfer between processes is required, significantly improving production efficiency. Simultaneously, automated processing avoids positioning and processing errors caused by manual operation. Combined with the waste adsorption function of the vacuum vents, it effectively reduces surface defects, dimensional deviations, and other defects, keeping the defect rate below 0.5%.

[0052] Comparative Example 1's traditional secondary processing technology requires multiple machines to complete bearing forming, convex stamping, and lubricant layer milling separately. The time spent on workpiece transfer between processes accounts for more than 60%, and secondary clamping and positioning are prone to dimensional errors. The production efficiency is only 6850 pieces / h, and the defect rate is as high as 3.5%. Comparative Example 2 uses a punching and extension process, which is a single-process processing mode. It requires the preparation of a composite body first, then punching through holes separately, and finally rolling and flanging. The processing cycle is long, with a production efficiency of 7100 pieces / h. Improper control of punching parameters can easily lead to out-of-tolerance through hole dimensions, with a defect rate of 1.8%. Comparative Example 3's fixed scraper process integrates some processes, but the external cylinder is not synchronized with the stamping cycle, which can easily lead to uneven scraping depth and waste residue. The production efficiency is 7300 pieces / h, and the defect rate is 2.1%. The commercially available bearings in the blank control use a traditional manual-assisted processing technology, which has low processing accuracy and slow efficiency, with a production efficiency of only 6500 pieces / h and a defect rate of 4.2%.

[0053] Finally, it should be noted that the above embodiments are used to illustrate the technical solutions of the present invention and not to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A conductive integrated molding process for non-conductive self-lubricating bearings, characterized in that, Includes the following steps: S1. Embossing stamping: The composite strip is conveyed to the first station of the progressive die, and 2-3 circular embosses are formed by stamping the strip at the preset position using a stamping head; S2. Lubricating layer scraping: The stamped strip with the convex bump is conveyed to the second station of the progressive die. The wedge (202) mechanism with an inclination angle of 30°-45° is driven by the stamping pressure to drive the scraper (203) to scrape the top of the convex bump to a fixed depth, so that the lubricating layer at the top of the convex bump is removed to form a boss (204) with exposed metal base. The cutting edge angle of the scraper (203) is 20°-30°. S3. Slicing and cutting: The scraped strip is conveyed to the third station of the progressive die, and the strip is sliced ​​into individual sheet blanks using a slicer (201); S4. Rolling: The sheet blank is conveyed to the fourth station of the progressive die, and the blank is rolled into a hollow cylinder by the rolling die. The diameter of the mandrel of the rolling die is the nominal inner diameter of the bearing. S5. Extrusion shaping: The hollow cylindrical blank is conveyed to the fifth station of the progressive die, and extrusion shaping is performed using a shaping die. S6. Stamping and Flanging: The shaped blank is conveyed to the sixth station of the progressive die, and the stamping and flanging is completed using a flanging die.

2. The process according to claim 1, characterized in that: The composite strip is composed of a conductive metal mesh base and a PTFE composite material lubricating layer. The conductive metal mesh is selected from at least one of copper alloy woven mesh, copper alloy punched mesh, aluminum-coated steel punched mesh, or aluminum alloy punched mesh. The diameter of the conductive metal mesh wires is 0.1mm-0.2mm, the mesh size is 0.5mm×0.5mm-1.0mm×1.0mm, and the thickness is 0.2mm-0.4mm. The PTFE composite material lubricating layer has a coating thickness of 0.1mm-0.3mm, and the total thickness of the composite strip is 0.3mm-0.7mm.

3. The process according to claim 1, characterized in that: The wedge (202) mechanism in step S2 is equipped with a separable shovel (203). The shovel (203) and the wedge (202) mechanism are connected by a slot, with a slot clearance of 0.01mm-0.02mm. The shovel (203) replacement time is ≤5min.

4. The process according to claim 1, characterized in that: The second and third stations of the progressive die are both equipped with pore structures. The pore diameter is 0.8mm-1.2mm, and there are 2-4 pores per station. The vacuum degree inside the pores is -0.06MPa--0.09MPa, which is used to adsorb the lubricating waste generated by scraping.

5. The process according to claim 1, characterized in that: After scraping is completed in step S2, the exposed metal substrate of the convex bulge is deburred by a brush roller. The brush roller rotates at a speed of 300 r / min-500 r / min and the contact pressure with the material strip is 0.5 MPa-1.0 MPa.

6. The process according to claim 1, characterized in that: The material conveying between each station of the six-station progressive die adopts synchronous belt drive, with a conveying speed of 30mm / s-50mm / s. The processing cycle of each station is synchronized, and the processing cycle of a single finished product is ≤8s.

7. The process according to claim 2, characterized in that: The copper alloy woven mesh is a tin bronze alloy mesh with a tin content of 5wt%-8wt% and a copper content of 92wt%-95wt%, and the weaving method is plain weave; the PTFE composite material lubricating layer is made of 10wt%-20wt% glass fiber, 3wt%-5wt% molybdenum disulfide and the balance PTFE.

8. The process according to claim 1, characterized in that: In the rolling process of step S4, the rolling temperature of the blank is 60℃-80℃, and hot air heating is used with a heating wind speed of 2m / s-4m / s.

9. The process according to claim 1, characterized in that: After the stamping and flanging in step S6 is completed, the finished bearing is cleaned and dried. The cleaning is carried out using hydrocarbon cleaning for 2-5 minutes, and the drying is carried out using hot air drying at a temperature of 80℃-100℃ for 10-15 minutes.

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