A method of making a surface textured clutch plate

Abstract

This invention belongs to the field of clutch manufacturing technology and aims to solve the problem that the friction performance of existing heavy-duty clutches gradually decreases over time, thus affecting their transmission smoothness and shortening their service life. To this end, this invention provides a method for preparing a surface-textured clutch plate. The method includes: preparing a mixed powder comprising metal matrix powder, solid lubricant powder, reinforcing phase powder, and a forming agent, and mixing them uniformly in a predetermined ratio; loading the mixed powder into a mold for cold pressing to obtain a green blank with a predetermined geometric structure; sintering the green blank under a protective atmosphere with stepped heating; processing microtextures on the friction surface of the sintered part using an ultrasonic impact device; and cleaning the surface of the ultrasonically impacted workpiece. This invention can optimize the friction performance of the clutch, enabling it to maintain high friction characteristics for a long time and preventing a rapid reduction in the clutch's service life.

Description

Technical Field

[0001] This invention relates to the field of clutch manufacturing technology, and specifically to a method for preparing a surface-textured clutch disc. Background Technology

[0002] As a key component of mechanical transmission systems, the clutch plays an indispensable role in the starting, shifting, and power interruption processes of heavy-duty vehicles (such as heavy trucks, construction machinery, and mining equipment). These vehicles operate under extreme conditions, often accompanied by high torque, high inertial loads, frequent starts and stops, and intense sliding friction. This places extremely stringent requirements on the overall performance of the clutch disc: it not only needs a high coefficient of friction to ensure effective power transmission, but also requires a stable coefficient of friction, long wear life, strong resistance to thermal degradation, and the ability to effectively manage the wear debris and heat generated during friction.

[0003] Currently, powder metallurgy technology is widely used in the manufacture of clutch plates due to its advantages such as the ability to prepare complex shapes, controllable composition, and the presence of self-lubricating phases. Common improvement methods include optimizing the ratio of iron-based powder with solid lubricants such as graphite and molybdenum disulfide, or strengthening the matrix by adding alloying elements such as copper and tin. However, these methods mainly focus on optimizing the properties of the material itself and have limited ability to actively design and control the friction interface. As the service time increases, wear debris will accumulate at the friction interface, leading to fluctuations in the coefficient of friction, noise and vibration, and even surface scratches and hot spots, ultimately affecting the smoothness of transmission and shortening the clutch life.

[0004] Therefore, there is a need in the field for a new method for preparing clutch plates to solve the above problems. Summary of the Invention

[0005] In order to solve the above-mentioned technical problems, namely the problem that the friction performance of existing heavy-duty clutches gradually decreases over time, thereby affecting their transmission smoothness and shortening their service life.

[0006] This invention provides a method for preparing a surface-textured clutch plate, the method comprising:

[0007] S1: Prepare a mixed powder comprising metal matrix powder, solid lubricant powder, reinforcing phase powder and forming agent, and mix them evenly according to a predetermined ratio;

[0008] S2: The mixed powder is loaded into a mold and cold-pressed to obtain a green body with a preset geometric structure;

[0009] S3: The green body is sintered by step heating under a protective atmosphere;

[0010] S4: Microtextures are fabricated on the friction surface of sintered parts using an ultrasonic impact device;

[0011] S5: Clean the surface of the workpiece after ultrasonic impact treatment.

[0012] In some preferred embodiments, in step S1, the metal matrix powder is reduced iron powder, the solid lubricant powder includes flake graphite powder and molybdenum disulfide powder, the reinforcing phase powder is pre-alloyed bronze powder, and the forming agent is zinc stearate powder, wherein the particle size of all powders is between 200 mesh and 400 mesh.

[0013] In some preferred embodiments, in step S1, the mixed powders are: 82wt%-88wt% reduced iron powder, 6wt%-8wt% flake graphite powder, 2wt%-3.5wt% molybdenum disulfide powder, 4wt%-6wt% pre-alloyed bronze powder, and 0.5wt%-1.0wt% zinc stearate powder by mass percentage.

[0014] In some preferred embodiments, in step S1, the powder is mixed evenly using a double cone or V-type mixer, with the mixer speed being 30 rpm to 50 rpm and the mixing time being greater than or equal to 4 hours.

[0015] In some preferred embodiments, in step S2, the cold pressing pressure is 650 MPa to 850 MPa, and the holding time is 90 seconds to 150 seconds.

[0016] In some preferred embodiments, step S3 specifically includes:

[0017] S31: Place the green blank in the sintering furnace and introduce a reducing protective atmosphere;

[0018] S32: Increase the temperature from room temperature to 550°C to 650°C at a rate of 3°C / min to 8°C / min, and hold at that temperature for 60 minutes to 120 minutes;

[0019] S33: Continue heating at a rate of 5℃ / min to 10℃ / min to 1120℃ to 1180℃, and hold for 120 minutes to 180 minutes;

[0020] S34: Cool down to below 600°C at a rate of 2°C / min to 5°C / min, and then cool to room temperature with the furnace.

[0021] In some preferred embodiments, in step S4, the process parameters of the ultrasonic impact device are in the following ranges: ultrasonic frequency 18kHz to 22kHz, amplitude 25μm to 55μm, impact static pressure 0.1MPa to 0.25MPa, and scanning feed speed 150mm / min to 400mm / min.

[0022] In some preferred embodiments, the microtexture is a micro-pit array, wherein the micro-pit array is a rectangular array, an equilateral triangular array, or a rhomboid array, the longitudinal cross-section of the micro-pit is arc-shaped, the depth of the micro-pit is 40μm to 120μm, and the opening size of the micro-pit is 150μm to 350μm.

[0023] In some preferred embodiments, the microtexture is a grid-like groove, wherein the longitudinal cross-section of the groove is arc-shaped or trapezoidal, the depth of the groove is 50 μm to 100 μm, and the opening width of the groove is 120 μm to 300 μm.

[0024] In some preferred embodiments, in step S5, a compressed air purging device is used to blow the surface of the workpiece after ultrasonic impact treatment; or,

[0025] In step S5, an ultrasonic cleaning machine is used to clean the surface of the workpiece after ultrasonic impact treatment.

[0026] The method for preparing the surface-textured clutch plate of the present invention has the following beneficial effects:

[0027] This invention employs ultrasonic impact treatment to achieve an integrated process of workpiece surface processing and strengthening. While plastically forming a precisely controllable microtexture on the friction surface, the intense plastic deformation induced by high-energy impact simultaneously achieves grain nano-sizing of the surface layer and the introduction of residual compressive stress. The microtexture is no longer an isolated geometric shape, but forms an organic whole with a reinforcing layer that has ultra-high hardness, excellent wear resistance, and fatigue resistance. The microtexture can improve friction performance, while the nanocrystalline reinforcing layer and compressive stress field provide it with robust mechanical support, significantly improving the durability of the texture and the fatigue life of the substrate.

[0028] More specifically, by combining the optimized powder composition design in step S1 with the microtexture constructed in step S4, the tribological performance of the clutch disc under extreme operating conditions is fundamentally improved. The microtexture effectively captures and accommodates wear particles, preventing them from participating in three-body wear, thereby stabilizing the friction coefficient and reducing vibration and noise. Simultaneously, the texture, acting as a micro-oil reservoir or drainage channel, helps retain and distribute the lubricant, improves heat dissipation, and effectively resists thermal degradation. The residual compressive stress introduced on the surface greatly inhibits the generation and propagation of microcracks, collectively resulting in a significant improvement in the wear resistance and overall service life of the clutch disc.

[0029] Meanwhile, steps S1 to S4 form a complete preparation chain. Powder metallurgy ensures the uniformity of the clutch plate matrix composition and the ability to form complex structures in one step. The ultrasonic impact technology, used as a post-processing step, offers high flexibility. By simply changing the impact pin array or adjusting the CNC path, different types, sizes, and distributions of microtextures can be rapidly processed on the friction surface without changing the mold, meeting the customized needs of different application scenarios. The entire process is stable and controllable, facilitating large-scale production. Compared to traditional surface texturing technologies such as laser processing, the ultrasonic impact of this invention is an additive combined with plastic forming process. It does not generate cutting debris or cause material phase transformation, heat-affected zones, or microcracks due to heat input. Instead, it imparts a beneficial strengthening effect to the surface during processing, ensuring the integrity and reliability of the matrix material, optimizing the clutch's friction performance, maintaining high friction characteristics for a long time, and preventing a rapid reduction in clutch lifespan. Attached Figure Description

[0030] The features and advantages of the invention will be more clearly understood by referring to the accompanying drawings, which are schematic and should not be construed as limiting the invention in any way. In the drawings:

[0031] Figure 1 This is a flowchart of the method for preparing the surface-textured clutch plate of the present invention. Detailed Implementation

[0032] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0033] Based on the problem pointed out in the background art that the friction performance of existing heavy-duty clutches gradually decreases over time, thereby affecting their transmission smoothness and shortening their service life, the present invention provides a method for preparing a surface-textured clutch plate, which aims to optimize the friction performance of the clutch, enable it to maintain high friction characteristics for a long time, and avoid the rapid reduction of the clutch's service life.

[0034] like Figure 1 As shown, the method for preparing the surface-textured clutch plate of the present invention includes:

[0035] S1: Prepare a mixed powder comprising metal matrix powder, solid lubricant powder, reinforcing phase powder and forming agent, and mix them evenly according to a predetermined ratio.

[0036] Preferably, in step S1 above, the metal matrix powder is reduced iron powder, the solid lubricant powder includes flake graphite powder and molybdenum disulfide powder, the reinforcing phase powder is pre-alloyed bronze powder, and the forming agent is zinc stearate powder. All powders have a particle size between 200 mesh and 400 mesh, and the mixed powder is, by mass percentage: 82wt%-88wt% reduced iron powder, 6wt%-8wt% flake graphite powder, 2wt%-3.5wt% molybdenum disulfide powder, 4wt%-6wt% pre-alloyed bronze powder, and 0.5wt% zinc stearate powder. 5wt%-1.0wt% of reduced iron powder forms the strong and tough matrix of the material. Graphite powder and molybdenum disulfide powder serve as solid lubricants, and pre-alloyed bronze powder acts as a reinforcing phase. During subsequent sintering, it generates a liquid phase, promoting densification through a liquid-phase sintering mechanism and forming a copper solid solution for strengthening, thus improving strength, thermal conductivity, and wear resistance. Zinc stearate acts as a forming agent, reducing friction between the powder and the mold wall, ensuring uniform compact density and complete demolding. Controlling all powders to between 200 and 400 mesh helps ensure uniform mixing and sintering activity. More preferably, the pre-alloyed bronze powder is Cu-10Sn, with copper accounting for approximately 90%, tin for approximately 10%, and other impurities (Fe, Pb, Zn, P, etc.) totaling no more than 0.5%.

[0037] In some preferred embodiments, in step S1 above, the powder is mixed evenly using a double cone or V-type mixer. The mixer speed is 30 rpm to 50 rpm, and the mixing time is greater than or equal to 4 hours. The double cone / V-type mixer can achieve gentle and thorough mixing, avoiding segregation of powders with large density differences. A mixing time of not less than 4 hours can ensure that the powder has a highly uniform composition, which is convenient for obtaining a sintered body with uniform microstructure and consistent performance in the subsequent process.

[0038] S2: The mixed powder is loaded into a mold and cold-pressed to obtain a green body with a preset geometric structure.

[0039] Preferably, in step S2 above, the cold pressing pressure is 650MPa to 850MPa, and the holding time is 90 seconds to 150 seconds. The high pressure causes the powder particles to plastically deform and mechanically interlock, forming a green blank with a certain strength. The holding time allows the pressure to be fully transmitted and the stress to be relaxed, preventing cracks caused by elastic aftereffects. Through repeated research and experiments by the inventors, it has been found that by setting the above pressure parameters and holding parameters within a certain range, a green blank with high density, high precision and no defects can be obtained.

[0040] S3: The green body is sintered by step heating under a protective atmosphere.

[0041] Preferably, step S3 specifically includes:

[0042] S31: Place the green billet in the sintering furnace and introduce a reducing protective atmosphere. Preferably, the reducing protective atmosphere is a decomposed ammonia protective atmosphere. The nitrogen in the decomposed ammonia atmosphere plays a protective role in diluting, filling and isolating air, while the hydrogen in the decomposed ammonia atmosphere provides a reducing atmosphere.

[0043] S32: Heat from room temperature to 550°C to 650°C at a rate of 3°C / min to 8°C / min and hold for 60 to 120 minutes. The purpose of this stage is degreasing and pre-sintering. Organic forming agents such as zinc stearate have a wide decomposition and evaporation temperature range, requiring a sufficiently long holding time to ensure that they are completely decomposed into gaseous products and smoothly diffused out from the interior of the green body. The inventors have found that if the temperature rises too quickly or the holding time is insufficient in this stage, the forming agent will vaporize violently, causing the green body to bubble, crack, or leave carbon residue, which seriously damages the integrity of the matrix. At the same time, this stage also partially reduces the oxides on the surface of the powder particles by the reducing atmosphere and prepares the body for subsequent high-temperature sintering.

[0044] S33: Continue heating at a rate of 5℃ / min to 10℃ / min to 1120℃ to 1180℃, and hold for 120 minutes to 180 minutes. This stage is crucial for densification and alloying. The inventors discovered that at this temperature, atoms gain sufficient diffusion kinetic energy, and solid sintering necks are formed between iron powder particles through atomic diffusion, causing the material to shrink and densify. More importantly, the Cu-Sn bronze powder melts into a liquid phase at this temperature, rapidly filling the pores between powder particles through capillary force and dissolving some iron atoms, greatly promoting material migration and pore elimination. Subsequently, during cooling, elements such as copper and tin precipitate in solid solution form, playing a solid solution strengthening role.

[0045] S34: Cool down to below 600℃ at a rate of 2℃ / min to 5℃ / min, and then cool to room temperature with the furnace. The purpose of this stage is to obtain an ideal microstructure and reduce internal stress. The inventors found that excessively rapid cooling will generate large thermal stress and microstructure stress, which will lead to workpiece deformation or even cracking. Slow cooling allows austenite to transform into an ideal metallographic structure, such as ferrite and pearlite, according to the iron-carbon phase diagram. At the same time, it allows the liquid phase to solidify uniformly, avoids component segregation, and obtains a uniform microstructure.

[0046] The above-mentioned sintering process ensures the integrity of the matrix, fundamentally avoiding macroscopic defects and microscopic pores caused by residual or violently volatilized forming agents, laying the foundation for high-performance matrices. At the same time, it combines the advantages of solid-state sintering and liquid-state sintering, achieving a density far exceeding that of a single sintering mechanism, thus obtaining a high-strength matrix. Precise cooling rate control ensures the final acquisition of a uniform and stable metallographic structure, giving the material excellent comprehensive mechanical properties, including strength, toughness, and hardness.

[0047] S4: Microtextures are fabricated on the friction surface of sintered parts using an ultrasonic impact device.

[0048] Preferably, in step S4 above, the process parameters of the ultrasonic impact device are: ultrasonic frequency 18kHz to 22kHz, amplitude 25μm to 55μm, impact static pressure 0.1MPa to 0.25MPa, and scanning feed speed 150mm / min to 400mm / min. The inventors have found that this ultrasonic frequency range ensures efficient energy transfer of ultrasound in metallic materials. Too low a frequency leads to insufficient impact force, while too high a frequency results in rapid energy attenuation and makes equipment manufacturing difficult. Setting the amplitude to 25μm to 55μm achieves this. This design avoids both insufficient amplitude to induce effective plastic deformation and excessive amplitude to prevent over-processing or even damage to the surface. Setting the impact static pressure to 0.1MPa to 0.25MPa ensures stable contact between the impact pin and the workpiece surface, guaranteeing that the energy from each vibration is effectively transferred to the workpiece rather than dissipated in the air. The aforementioned scanning feed speed ensures higher scanning coverage while maintaining processing efficiency, resulting in greater cumulative plastic deformation energy in the area, more significant texture depth and strengthening effect, achieving an optimal balance between processing effect and processing efficiency.

[0049] In one possible scenario, the microtexture is an array of micro-pits, which can be rectangular, equilateral triangular, or rhomboid. The longitudinal cross-section of the micro-pits is arc-shaped, with a depth of 40 μm to 120 μm and an opening size of 150 μm to 350 μm. An equilateral triangular array, also known as hexagonal close-packed microtexture, is the most uniform distribution, ensuring uniform texture density and consistent tribological behavior on the friction surface in any direction, thus avoiding anisotropy. Rectangular arrays have a relatively simple processing path. The arc-shaped cross-section achieves a smooth transition with the substrate, minimizing stress concentration caused by abrupt geometric changes at the texture edge. This is crucial for friction pairs operating under alternating loads, effectively suppressing fatigue crack formation. Through repeated research, the inventors discovered that the depth and opening size range of the aforementioned micro-pits can avoid an insufficient chip storage and lubrication capacity due to an excessively small depth-to-diameter ratio, and also avoid an excessively large ratio that weakens the substrate's bearing area and reduces mechanical properties. The aforementioned range achieves the best balance between functionality and structure.

[0050] In another possible scenario, the microtexture is a grid-like groove, wherein the longitudinal cross-section of the groove is arc-shaped or trapezoidal, the groove depth is 50μm to 100μm, and the groove opening width is 120μm to 300μm. The arc-shaped cross-section has low stress concentration; the trapezoidal cross-section is easier to precisely shape by controlling the shape and parameters of the impact pin, and has better drainage effect. The groove can achieve directional drainage and partitioning, and the cross-grid can divide the entire friction surface into countless independent micro-contact blocks, which helps to suppress frictional vibration and noise. The continuity of the groove can also effectively discharge wear debris and heat from the contact center area to the edge.

[0051] S5: Clean the surface of the workpiece after ultrasonic impact treatment.

[0052] Preferably, in step S5, a compressed air blowing device is used to blow the surface of the workpiece after ultrasonic impact treatment; or, in step S5, an ultrasonic cleaning machine is used to clean the surface of the workpiece after ultrasonic impact treatment. Thorough cleaning ensures that the friction pair is in the best contact state from the moment it starts working.

[0053] The technical solution of the present invention will be further illustrated below with reference to several embodiments.

[0054] Example 1

[0055] First, the mixed powders were prepared and mixed as follows: 85.0 kg of reduced iron powder (300 mesh), 7.0 kg of flake graphite powder, 2.5 kg of molybdenum disulfide powder, 5.0 kg of Cu-10Sn pre-alloyed bronze powder, and 0.5 kg of zinc stearate were weighed and added to a double cone mixer. The mixture was continuously mixed at 40 rpm for 4.0 hours to obtain a homogeneous powder. Next, cold pressing was performed. The mixed powder was placed into a special mold, and a unidirectional pressing pressure of 750 MPa was applied to a mechanical press and held for 100 seconds to obtain a green body with a predetermined geometric shape. Following this, a densification treatment was performed. The green blank was placed in a mesh belt sintering furnace with a protective atmosphere of decomposed ammonia. The temperature was first raised to 600°C at a rate of 5°C / min and held for 90 minutes to remove the forming agent. Then, the temperature was raised to 1150°C at a rate of 8°C / min and held for 150 minutes to complete high-temperature sintering. Finally, the temperature was slowly cooled to below 600°C at a controlled cooling rate of 3°C / min, followed by furnace cooling to obtain a dense sintered part. Next, ultrasonic impact surface texturing was performed using an ultrasonic impact device with a frequency of 20 kHz and an amplitude of 35 μm, equipped with a 1.0 mm diameter spherical cemented carbide impact needle. Under a static pressure of 0.15 MPa and a scanning speed of 200 mm / min, an array of equilateral triangular micro-pits was machined on the friction surface of the sintered part. The pits were approximately 60 μm deep and 220 μm in diameter. Finally, the surface of the workpiece was thoroughly cleaned using 0.6 MPa compressed air to obtain the final product.

[0056] Example 2

[0057] First, the mixed powders were prepared and mixed as follows: 83.0 kg of reduced iron powder (300 mesh), 8.0 kg of flake graphite powder, 3.5 kg of molybdenum disulfide powder, 5.2 kg of Cu-10Sn pre-alloyed bronze powder, and 0.8 kg of zinc stearate were weighed and added to a double cone mixer. The mixture was continuously mixed at 40 rpm for 4.0 hours to obtain a homogeneous powder. Next, cold pressing was performed. The mixed powder was placed into a special mold, and a unidirectional pressing pressure of 700 MPa was applied to a mechanical press and held for 110 seconds to obtain a green body with a predetermined geometric shape. Following this, a densification treatment was performed. The green blank was placed in a mesh belt sintering furnace with a protective atmosphere of decomposed ammonia. The temperature was first raised to 600°C at a rate of 5°C / min and held for 90 minutes to remove the forming agent. Then, the temperature was raised to 1150°C at a rate of 8°C / min and held for 150 minutes to complete high-temperature sintering. Finally, the temperature was slowly cooled to below 600°C at a controlled cooling rate of 3°C / min, followed by furnace cooling to obtain a dense sintered part. Next, ultrasonic impact surface texturing was performed using an ultrasonic impact device with a frequency of 20 kHz and an amplitude of 35 μm, equipped with a 1.0 mm diameter spherical cemented carbide impact needle. Under a static pressure of 0.15 MPa and a scanning speed of 200 mm / min, an array of equilateral triangular micro-pits was machined on the friction surface of the sintered part. The pits were approximately 60 μm deep and 220 μm in diameter. Finally, the surface of the workpiece was thoroughly cleaned using 0.6 MPa compressed air to obtain the final product.

[0058] Example 3

[0059] First, the mixed powders were prepared and mixed as follows: 87.0 kg of reduced iron powder (300 mesh), 6.0 kg of flake graphite powder, 2.0 kg of molybdenum disulfide powder, 5.5 kg of Cu-10Sn pre-alloyed bronze powder, and 0.5 kg of zinc stearate were weighed and added to a double cone mixer. The mixture was continuously mixed at 40 rpm for 4.0 hours to obtain a homogeneous powder. Next, cold pressing was performed. The mixed powder was placed into a special mold, and a unidirectional pressing pressure of 800 MPa was applied to a mechanical press and held for 90 seconds to obtain a green body with a predetermined geometric shape. Following this, a densification treatment was performed. The green blank was placed in a mesh belt sintering furnace with a protective atmosphere of decomposed ammonia. The temperature was first raised to 600°C at a rate of 5°C / min and held for 90 minutes to remove the forming agent. Then, the temperature was raised to 1150°C at a rate of 8°C / min and held for 150 minutes to complete high-temperature sintering. Finally, the blank was slowly cooled to below 600°C at a controlled cooling rate of 3°C / min, followed by furnace cooling to obtain a dense sintered part. Next, ultrasonic impact surface texturing was performed using an ultrasonic impact device with a frequency of 20 kHz and an amplitude of 50 μm, equipped with a 1.0 mm diameter spherical cemented carbide impact needle. Under a static pressure of 0.20 MPa and a scanning speed of 150 mm / min, an array of equilateral triangular micro-pits was machined on the friction surface of the sintered part. The pits were approximately 75 μm deep and 220 μm in diameter. Finally, the surface of the workpiece was thoroughly cleaned using 0.6 MPa compressed air to obtain the final product.

[0060] Example 4

[0061] First, the mixed powders were prepared and mixed as follows: 85.0 kg of reduced iron powder (300 mesh), 7.0 kg of flake graphite powder, 2.5 kg of molybdenum disulfide powder, 5.0 kg of Cu-10Sn pre-alloyed bronze powder, and 0.5 kg of zinc stearate were weighed and added to a double cone mixer. The mixture was continuously mixed at 40 rpm for 4.0 hours to obtain a homogeneous powder. Next, cold pressing was performed. The mixed powder was placed into a special mold, and a unidirectional pressing pressure of 750 MPa was applied to a mechanical press and held for 100 seconds to obtain a green body with a predetermined geometric shape. Following this, a densification treatment was performed. The green blank was placed in a mesh belt sintering furnace with a protective atmosphere of decomposed ammonia. First, the temperature was raised to 600 degrees Celsius at a rate of 5 degrees Celsius / minute and held for 90 minutes to remove the forming agent. Then, the temperature was raised to 1150 degrees Celsius at a rate of 8 degrees Celsius / minute and held for 150 minutes to complete high-temperature sintering. Finally, the cooling rate was controlled at 3 degrees Celsius / minute to slowly cool to below 600 degrees Celsius and then cooled with the furnace to obtain a dense sintered part. Then, ultrasonic impact surface texturing was performed. An ultrasonic impact device with a frequency of 20 kHz and an amplitude of 35 micrometers was used, equipped with a flat-headed conical cemented carbide impact needle with an equivalent width of 150 micrometers. Under a static pressure of 0.15 MPa and a scanning speed of 300 mm / minute, a grid-like groove was machined on the friction surface of the sintered part by cross-scanning. The groove depth was about 70 micrometers, the width was about 180 micrometers, and the cross-section was trapezoidal. Finally, the surface of the workpiece is thoroughly cleaned by blowing away compressed air at 0.6 MPa to obtain the final product.

[0062] Example 5

[0063] First, the mixed powders were prepared and mixed as follows: 85.0 kg of reduced iron powder (300 mesh), 7.0 kg of flake graphite powder, 2.5 kg of molybdenum disulfide powder, 5.0 kg of Cu-10Sn pre-alloyed bronze powder, and 0.5 kg of zinc stearate were weighed and added to a double cone mixer. The mixture was continuously mixed at 40 rpm for 4.0 hours to obtain a homogeneous powder. Next, cold pressing was performed. The mixed powder was placed into a special mold, and a unidirectional pressing pressure of 750 MPa was applied to a mechanical press and held for 100 seconds to obtain a green body with a predetermined geometric shape. Following this, a densification process was performed. The green blank was placed in a mesh belt sintering furnace with a protective atmosphere of decomposed ammonia. The temperature was first raised to 600°C at a rate of 5°C / min and held for 90 minutes to remove the forming agent. Then, the temperature was raised to 1150°C at a rate of 8°C / min and held for 150 minutes to complete high-temperature sintering. Finally, the blank was slowly cooled to below 600°C at a controlled cooling rate of 3°C / min, followed by furnace cooling to obtain a dense sintered part. Ultrasonic impact surface texturing was then performed using an ultrasonic impact device with a frequency of 20 kHz and an amplitude of 35 μm, equipped with a 1.0 mm diameter spherical cemented carbide impact needle. Under a static pressure of 0.12 MPa and a scanning speed of 380 mm / min, an array of equilateral triangular micro-pits was machined on the friction surface of the sintered part. The pits were approximately 45 μm deep and 220 μm in diameter. Finally, the surface of the workpiece was thoroughly cleaned using 0.6 MPa compressed air to obtain the final product.

[0064] The following is a performance comparison table of the final products prepared in Examples 1-5:

[0065]

[0066] As can be seen from the table above, the overall performance parameters in Example 1 are more balanced; Example 2, due to the higher content of graphite and molybdenum disulfide, enables the final product to form a continuous and stable solid lubricating film more quickly during friction, thus achieving a lower and more stable coefficient of friction; Example 3, due to the increased content of iron matrix and reinforcing phase and the use of higher ultrasonic impact energy, results in higher material strength, a deeper nanocrystalline layer on the surface, and higher residual compressive stress. This strong compressive stress field can effectively inhibit the propagation of fatigue cracks, thus giving the product optimal wear resistance and fatigue life; Example 4, due to the use of a grid-like groove texture, provides an efficient directional drainage channel at the friction interface, enabling rapid discharge of wear debris and heat, thus exhibiting excellent wear debris management capabilities and interface stability; Example 5, due to the use of a higher scanning feed rate, results in a relatively reduced impact energy absorbed per unit area, leading to a slight decrease in the depth of the textured reinforcement layer and the level of residual compressive stress, which clearly demonstrates a controllable trade-off between processing efficiency and performance depth.

[0067] It should be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0068] The various embodiments in this invention are described in a progressive manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments.

[0069] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of this disclosure is limited to these examples; within the framework of this disclosure, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of the present invention as described above, which are not provided in detail for the sake of brevity.

[0070] Although this disclosure has been described in conjunction with specific embodiments thereof, many substitutions, modifications and variations of these embodiments will be apparent to those skilled in the art from the foregoing description.

[0071] One or more embodiments of the present invention are intended to cover all such substitutions, modifications, and variations that fall within the scope of protection of the present invention. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments of the present invention should be included within the scope of protection of this disclosure.

Claims

1. A method for preparing a surface-textured clutch plate, characterized in that, The preparation method includes: S1: Prepare a mixed powder comprising metal matrix powder, solid lubricant powder, reinforcing phase powder and forming agent, and mix them evenly according to a predetermined ratio; In step S1, the metal matrix powder is reduced iron powder, the solid lubricant powder includes flake graphite powder and molybdenum disulfide powder, the reinforcing phase powder is pre-alloyed bronze powder, and the forming agent is zinc stearate powder. All powders have a particle size between 200 and 400 mesh, and the mixed powder is distributed as follows by mass percentage: 82wt%-88wt% reduced iron powder, 6wt%-8wt% flake graphite powder, 2wt%-3.5wt% molybdenum disulfide powder, 4wt%-6wt% pre-alloyed bronze powder, and 0.5wt%-1.0wt% zinc stearate powder. S2: The mixed powder is loaded into a mold and cold-pressed to obtain a green body with a preset geometric structure; S3: The green body is sintered by step heating under a protective atmosphere; S4: Microtextures are fabricated on the friction surface of sintered parts using an ultrasonic impact device; S5: Clean the surface of the workpiece after ultrasonic impact treatment.

2. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, In step S1, the powder is mixed evenly using a double cone or V-type mixer. The mixer speed is 30 rpm to 50 rpm, and the mixing time is greater than or equal to 4 hours.

3. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, In step S2, the cold pressing pressure is 650 MPa to 850 MPa, and the holding time is 90 seconds to 150 seconds.

4. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, Step S3 specifically includes: S31: Place the green blank in the sintering furnace and introduce a reducing protective atmosphere; S32: Increase the temperature from room temperature to 550°C to 650°C at a rate of 3°C / min to 8°C / min, and hold at that temperature for 60 minutes to 120 minutes; S33: Continue heating at a rate of 5℃ / min to 10℃ / min to 1120℃ to 1180℃, and hold for 120 minutes to 180 minutes; S34: Cool down to below 600°C at a rate of 2°C / min to 5°C / min, and then cool to room temperature with the furnace.

5. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, In step S4, the process parameters of the ultrasonic impact device are as follows: ultrasonic frequency 18kHz to 22kHz, amplitude 25μm to 55μm, impact static pressure 0.1MPa to 0.25MPa, and scanning feed speed 150mm / min to 400mm / min.

6. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, The microtexture is an array of micro-pits, wherein the micro-pit array is a rectangular array, an equilateral triangular array, or a rhomboid array, the longitudinal cross-section of the micro-pits is arc-shaped, the depth of the micro-pits is 40μm to 120μm, and the opening size of the micro-pits is 150μm to 350μm.

7. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, The microtexture is a grid-like groove, wherein the longitudinal cross-section of the groove is arc-shaped or trapezoidal, the depth of the groove is 50μm to 100μm, and the opening width of the groove is 120μm to 300μm.

8. The method for preparing a surface-textured clutch plate according to claim 1, characterized in that, In step S5, a compressed air blowing device is used to blow the surface of the workpiece after ultrasonic impact treatment; or, In step S5, an ultrasonic cleaning machine is used to clean the surface of the workpiece after ultrasonic impact treatment.

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