Heat-deformation-resistant gradient clutch friction plate and manufacturing method

Abstract

The invention discloses a heat-deformation-resistant gradient clutch friction plate and a manufacturing method, the friction plate comprises an annular core plate, friction linings are arranged on the two sides of the core plate, and spline teeth are arranged on the inner ring of the core plate. The manufacturing method comprises the steps of raw material mixing, cold pressing, hot pressing sintering, product processing and detection. Compared with the prior art, the friction plate has the advantages that the radial gradient distribution of the friction plate is realized by adjusting the radial material components of the annular friction plate, so that the friction coefficient of the lining friction material of the friction plate from the inner ring to the outer ring is gradually reduced, and the heat conductivity coefficient is increased; a titanium carbide or carbide pickaxe layer strengthening structure is formed at a key interface in the sintering process, and the interface bonding force is further enhanced, so that the heat distribution of the friction plate in the joint process of a clutch is balanced, the heat difference between an inner ring and an outer ring of the friction plate is reduced, overheat corrosion and buckling deformation caused by surface heat stress concentration of the friction plate are improved, and the service life of the clutch is prolonged. The friction performance and the service life of the friction plate are improved.

Description

Technical Field

[0001] The invention relates to the technical field of gearbox clutch friction plates, and in particular to a gradient clutch friction plate resistant to thermal deformation and a manufacturing method thereof. Background Art

[0002] The clutch is an important part of the vehicle transmission system. It is directly connected to the engine in the automobile transmission system and is used to cut off and transmit power. The friction clutch relies on the friction torque of the shift clutch friction plate and the fixed element to transmit energy and achieve the output of different torques and speeds. With the continuous expansion of the demand for heavy-load and high-speed vehicles and construction machinery, the friction performance and dynamic strength of the clutch have a significant impact on the reliability, stability and service life of the shift. The material and structural design of the clutch friction plate directly determine the transmission performance of the clutch to a certain extent. Therefore, the study of the composition and structure of the clutch friction material is an effective means to improve the working efficiency of the clutch.

[0003] According to the working conditions, the clutch can be divided into dry clutch and wet clutch. However, no matter it is a dry clutch or a wet clutch, its main failure form is hot spot corrosion and warping deformation of the friction plate. This is because the difference in tangential linear velocity and heat dissipation of the annular friction plate during sliding wear causes a serious non-uniform thermal field, which leads to the concentration of thermal stress on the side surface of the friction plate close to the outer ring. At present, the following three methods are used to solve the thermal failure of the friction plate: 1. Use a new friction material formula to improve the overall thermal tolerance of the friction plate; 2. Generate a structure that strengthens the interface bonding between appropriate components to optimize the performance of the friction plate; 3. Improve the structure of the clutch to optimize the temperature rise and heat dissipation of the friction plate surface. However, these methods still cannot fundamentally solve the non-uniform heat distribution on the surface of the friction plate, and the problem of interface bonding between the matrix and the friction material will also affect its overall performance, which will still affect the service life and functionality of the friction plate.

[0004] By analyzing the relationship between the composition and performance of existing friction materials, the present invention proposes a material-structure coupling method to construct the spatial form of the friction plate, realize the gradient distribution of the friction plate surface material, thereby reducing the thermal difference on the friction plate surface and improving the comprehensive performance of the friction plate. This method not only takes into account the performance of the material itself, but also pays attention to the interface bonding between materials and the influence of structural design on thermal distribution, which is expected to more effectively solve the thermal failure problem of the friction plate. Summary of the invention

[0005] The purpose of the present invention is to provide a gradient clutch friction plate resistant to thermal deformation and a manufacturing method thereof, so as to solve the problems raised in the above-mentioned background technology.

[0006] In order to solve the above technical problems, the technical solution provided by the present invention is: a thermal deformation resistant gradient clutch friction plate, comprising an annular core plate, friction linings are arranged on both sides of the core plate, and spline teeth are arranged on the inner ring of the core plate;

[0007] The core plate has a thickness of 2 to 3 mm, an inner diameter of 110 to 130 mm, an outer diameter of 145 to 165 mm, and is made of 65Mn;

[0008] The friction linings on both sides are symmetrically distributed on both sides of the core plate, and the thickness is 0.5-0.7 mm. The inner diameter and outer diameter of the friction lining are consistent with those of the core plate.

[0009] The friction lining is divided into 4 to 8 sections along the radial direction, and the width of each section is 2 to 5 mm;

[0010] The friction lining is made of metal-based powder metallurgy friction material, the material composition type of each section is consistent, and the mass of each component changes gradiently along the radial direction;

[0011] Each section of the friction lining material includes a matrix component, an interface strengthening component, a lubricating component and a friction component;

[0012] The components of the matrix component of the first section of the inner ring contain 30-40 parts by weight of copper, iron, tin and zinc, the components of the interface strengthening component contain 1-3 parts by weight of titanium and pickaxe, the components of the lubricating component contain 4-8 parts by weight of graphite and molybdenum disulfide, and the components of the friction component contain 10-15 parts by weight of ferrochrome, titanium carbide and titanium diboride;

[0013] The friction component of the raw material of the second and subsequent segments of the inner ring is 1 to 2 parts less than that of the previous segment, and the matrix component is 1 to 2 parts more than that of the previous segment.

[0014] As a preferred solution, the weight ratio of the friction component to the lubricating component of the raw material of the second and subsequent segments of the inner ring is 0.1 to 0.2 higher than that of the previous segment.

[0015] As a preferred solution, the addition amount of each element of the matrix component is adjusted to ensure that the difference in density and porosity between adjacent sections of the friction lining is less than 5%.

[0016] A method for manufacturing a thermally deformable gradient clutch friction plate specifically comprises the following steps:

[0017] 1) Raw material mixing: Calculate the area ratio of each section to obtain the total weight ratio of each section of raw materials, and weigh the matrix component, interface strengthening component, lubrication component and friction component of each section according to the designed ratio, and then mix the weighed raw powder of each section in a planetary ball mill or mixer for 8 to 24 hours to obtain the composite raw material of each section;

[0018] 2) Cold pressing: Use a segmented feeder to evenly spread the mixed raw materials on the template surface in sections, then remove the segmented feeder to cold press the friction lining as a whole, with a pressure of 400 MPa, and keep the pressure for 3 minutes to obtain pressed powder tablets;

[0019] 3) Hot pressing sintering: The pressed powder sheet and the core plate are stacked and placed in a sintering furnace for hot pressing. The heating temperature is set to 900-980°C and the pressing pressure is 2-2.5MPa. After hot pressing for 1-2 hours, the friction sheet product is obtained and cooled in the furnace.

[0020] 4) Product processing and testing: The cooled friction plate products are machined to remove surface defects such as flash, polished, cleaned and dried, and the oil groove texture of the friction lining is processed to obtain the finished friction plate. Finally, the finished friction plate is quality tested, and qualified finished friction plates can be installed in the clutch for use.

[0021] The advantages of the present invention compared with the prior art are:

[0022] 1. The friction material of the friction lining is distributed in a radial gradient, so that the friction lining near the outer ring has a higher thermal conductivity and a lower friction coefficient than that of the inner ring. During the sliding and grinding process of the friction plate and the dual plate, the difference between the friction work done by the outer ring with a higher linear speed and the friction work done by the inner ring with a lower linear speed is greatly reduced. In addition, the thermal conductivity increased along the radial gradient is more in line with the thermal field distribution of the friction plate during the sliding and grinding process, which is beneficial to the overall heat dissipation of the friction plate. At the same time, by forming a structure that strengthens the interface bonding between the material components, the bonding force between the materials is further enhanced, making heat conduction more efficient, and more effectively improving the thermal field distribution of the friction surface, fundamentally avoiding the generation of thermal stress concentration, thereby significantly improving the overall thermal tolerance of the friction plate.

[0023] 2. The friction coefficient that decreases along the radial gradient can also improve the uneven wear of the friction surface, thereby increasing the uniform contact between the friction plate and the mating plate and improving the load transmission capacity of the clutch. In addition, the strengthening of the interface bonding structure can better fix the hard particles in the friction component, prevent these particles from falling off during the friction process to form third-body wear, and further improve the wear resistance of the friction plate. The gradient clutch friction plate improves the thermal field distribution on the surface, which helps to reduce the size of the friction plate and ensure the friction performance and service life of the friction plate with a large difference between the inner and outer rings but a smaller overall size. It is of great significance for the mechanical design of a smaller clutch without losing the load transmission capacity.

[0024] The gradient clutch friction plate improves the friction plate's resistance to thermal deformation, increases the friction performance and service life of the friction plate, and is also of great significance for optimizing the overall design of the clutch. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of the gradient clutch friction plate of the present invention.

[0026] Figure 2 It is a radial cross-sectional view of the gradient clutch friction plate of the present invention.

[0027] Figure 3 It is an axial front view of the gradient clutch friction plate of the present invention.

[0028] Figure 4 It is a schematic diagram of the TiC ceramic layer generated at the interface of the gradient clutch friction plate of the present invention.

[0029] Figure 5 It is a temperature distribution cloud diagram during the friction process of the homogeneous material of the present invention.

[0030] Figure 6 It is a temperature distribution cloud diagram of the gradient material during the friction process of the present invention.

[0031] Figure 7 It is a trend diagram of radial temperature variation of gradient and homogeneous material of the present invention.

[0032] As shown in the figure: 1. core plate, 2. friction lining, 3. spline teeth. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0034] In the description of the embodiments of the present invention, it should be noted that if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, or the orientation or position relationship in which the invented product is usually placed when used. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0035] In addition, the terms "horizontal", "vertical", "overhanging" and the like do not mean that the components must be absolutely horizontal or overhanging, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0036] In the description of the embodiments of the present invention, "plurality" means at least 2.

[0037] In the description of the embodiments of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] like Figure 1-3 As shown, a thermal deformation resistant gradient clutch friction plate is composed of a core plate and a friction lining. The core plate is annular, with a thickness t1 of 2-3mm, an inner diameter d1 of 110-130mm, and an outer diameter d2 of 145-165mm. The core plate is made of 65Mn, and spline teeth are provided on the inner ring of the core plate. The friction linings are symmetrically distributed on both sides of the core plate. The thickness t2 of the two layers of friction linings is 0.5-0.7mm, and the inner diameter and outer diameter are consistent with the core plate, which are 110-130mm and 145-165mm respectively. The friction lining is divided into 6 sections along the radial direction, from the inner ring to the outer ring of the friction lining, they are section I, section II, section III, section IV, section V, and section VI, and the width w of each section is 2-5mm.

[0039] The friction lining is a metal-based powder metallurgy friction material, and the material components of each section are consistent, while the mass of each component changes gradiently along the radial direction. Each section of raw materials is divided into a matrix component, an interface strengthening component, a lubricating component and a friction component.

[0040] The materials of Section I are formulated by weight as follows: 30 parts of copper, 3 parts of tin, and 2 parts of zinc in the matrix component, 1 part of titanium and 1 part of pick in the interface strengthening component, 5 parts of graphite and 2 parts of molybdenum disulfide in the lubricating component, and 10 parts of ferrochrome and 3 parts of titanium diboride in the friction component;

[0041] The materials of Section II are formulated by weight as follows: 31 parts of copper, 3 parts of tin, and 2 parts of zinc in the matrix component, 1 part of titanium and 1 part of pick in the interface strengthening component, 5 parts of graphite and 2 parts of molybdenum disulfide in the lubricating component, and 9 parts of ferrochrome and 3 parts of titanium diboride in the friction component;

[0042] The weight formula of materials for stage III is as follows: 32 parts of copper, 3 parts of tin, and 2 parts of zinc in the matrix component, 1 part of titanium and 1 part of pick in the interface strengthening component, 5 parts of graphite and 2 parts of molybdenum disulfide in the lubricating component, 8 parts of ferrochrome and 3 parts of titanium diboride in the friction component;

[0043] The materials of Section IV are formulated by weight as follows: 33 parts of copper, 3 parts of tin, and 2 parts of zinc in the matrix component, 1 part of titanium and 1 part of pick in the interface strengthening component, 5 parts of graphite and 2 parts of molybdenum disulfide in the lubricating component, and 7 parts of ferrochrome and 3 parts of titanium diboride in the friction component;

[0044] The materials of Section V are formulated by weight as follows: 34 parts of copper, 3 parts of tin, and 2 parts of zinc in the matrix component, 1 part of titanium and 1 part of pick in the interface strengthening component, 5 parts of graphite and 2 parts of molybdenum disulfide in the lubricating component, and 6 parts of ferrochrome and 3 parts of titanium diboride in the friction component;

[0045] The weight formula of the materials in Section VI is as follows: 35 parts of copper, 3 parts of tin, and 2 parts of zinc in the matrix component, 1 part of titanium and 1 part of pick in the interface strengthening component, 5 parts of graphite and 2 parts of molybdenum disulfide in the lubricating component, and 5 parts of ferrochrome and 3 parts of titanium diboride in the friction component.

[0046] The specific preparation process of the present invention is as follows:

[0047] Step 1: Mixing the raw materials

[0048] Calculate the area ratio of each section to get the total weight ratio of each section of raw materials. In this example, the total mass ratio of each section is: Section I: Section II: Section III: Section IV:

[0049] Section V: Section VI = 1: 1.05: 1.09: 1.14: 1.19: 1.24. The matrix component, interface strengthening component, lubrication component and friction component of each section are weighed according to the designed proportion, and then the weighed raw powder of each section is mixed in a planetary ball mill or a mixer for 8-24 hours to obtain the composite raw material of each section.

[0050] Step 2: Cold Pressing

[0051] The mixed raw materials were evenly spread on the template surface in sections using a segmented feeder, and then the segmented feeder was removed to cold-press the friction lining as a whole. The pressing pressure was 400 MPa, and the pressed powder sheets were obtained after maintaining the pressure for 3 minutes.

[0052] Step 3: Hot Pressing and Sintering

[0053] The pressed powder sheet and the core plate are stacked and placed in a sintering furnace for hot pressing. The heating temperature is set to 900-980°C and the pressing pressure is 2-2.5MPa. After hot pressing for 1-2 hours, the friction sheet product is obtained and cooled with the furnace.

[0054] Step 4: Product processing and testing

[0055] The cooled friction plate products are machined to remove defects such as flash on the surface, polished, cleaned and dried, and the oil groove texture of the friction lining is processed to obtain the finished friction plate. Finally, the finished friction plate is quality inspected, and qualified finished friction plate products can be installed in the clutch for use.

[0056] like Figure 4 As shown in the figure, by introducing interface strengthening components such as Ti, it is found that a TiC ceramic layer can be generated in situ on the interface by reacting with graphite. The in situ endogenous TiC ceramic layer is distributed between the copper matrix and the graphite phase, which can significantly enhance the interface bonding between the graphite and copper matrix, improve stress transfer and reduce crack propagation at the interface. At the same time, the TiC ceramic layer can give full play to its excellent lubricity and resistance to plastic deformation, reduce the fluctuation of wear rate and friction coefficient, improve the friction stability and resistance to thermal deformation of the material, and thus extend the service life of the material.

[0057] The present invention achieves radial gradient distribution by adjusting the radial material composition of the annular friction plate, so that the friction coefficient of the friction material of the friction plate lining gradually decreases and the thermal conductivity increases from the inner ring to the outer ring, and by reasonably adding elements, a titanium carbide or titanium carbide layer reinforcement structure is formed at the key interface during the sintering process, further enhancing the interface bonding force, thereby balancing the heat distribution of the friction plate during the clutch engagement process, reducing the thermal difference between the inner ring and the outer ring of the friction plate, improving the hot spot corrosion and warping deformation caused by the concentration of thermal stress on the surface, and improving the friction performance and service life of the friction plate.

[0058] The comparison between the gradient material of the present invention and the traditional homogeneous material during the friction process is as follows: Figure 5 , Figure 6 , Figure 7 shown.

[0059] During the transmission engagement process of the homogeneous friction plate, the linear speed of the inner ring and the outer ring differs by nearly 25% due to the size difference between them, which leads to a significant difference in the friction heat generation between the inner ring and the outer ring. The resulting thermal gradient will induce thermal warping of the friction plate and electrocorrosion of the outer ring, thus shortening its service life. The use of a gradient friction plate can control its radial friction coefficient, so that the friction coefficient shows a decreasing trend from the inside to the outside, aiming to achieve the uniformity of the overall temperature during the friction plate engagement process, avoid the overheating corrosion of the outer ring, make the inner ring and the outer ring have the same transmission efficiency, and enhance the transmission combination efficiency of the friction plate. In order to preliminarily prove the benefits of the gradient friction plate, the friction heat generation process of the homogeneous friction plate and the gradient friction plate was constructed by finite element analysis, as shown in the figure. The results show that the temperature difference between the inner ring and the outer ring in the gradient friction plate is only about one-tenth of that of the homogeneous friction plate, proving that the gradient material greatly reduces the difference between the friction work done by the outer ring with a higher linear speed and the friction work done by the inner ring with a lower linear speed during the friction heat generation process, which is beneficial to improve the resistance to thermal deformation and overall stability of the friction plate.

[0060] The present invention and its implementation methods are described above. This description is not restrictive. The friction plate structure and material formulation in the embodiment are only part of the embodiments of the present invention and are only used to explain the specific implementation process of the present invention. All other embodiments obtained based on the concept of gradient distribution of friction materials of the present invention are within the protection scope of the present invention.

Claims

1. A thermally deformable gradient clutch friction plate, characterized in that: It comprises an annular core plate, both sides of the core plate are provided with friction linings, and the inner ring of the core plate is provided with spline teeth; The core plate has a thickness of 2 to 3 mm, an inner diameter of 110 to 130 mm, an outer diameter of 145 to 165 mm, and is made of 65Mn; The friction linings on both sides are symmetrically distributed on both sides of the core plate, and the thickness is 0.5-0.7 mm. The inner diameter and outer diameter of the friction lining are consistent with those of the core plate. The friction lining is divided into 4 to 8 sections along the radial direction, and the width of each section is 2 to 5 mm; The friction lining is made of metal-based powder metallurgy friction material, the material composition type of each section is consistent, and the mass of each component changes gradiently along the radial direction; Each section of the friction lining material includes a matrix component, an interface strengthening component, a lubricating component and a friction component; The components of the matrix component of the first section of the inner ring contain 30-40 parts by weight of copper, iron, tin and zinc, the components of the interface strengthening component contain 1-3 parts by weight of titanium and pickaxe, the components of the lubricating component contain 4-8 parts by weight of graphite and molybdenum disulfide, and the components of the friction component contain 10-15 parts by weight of ferrochrome, titanium carbide and titanium diboride; The friction component of the raw material of the second and subsequent segments of the inner ring is 1 to 2 parts less than that of the previous segment, and the matrix component is 1 to 2 parts more than that of the previous segment.

2. The thermal deformation resistant gradient clutch friction plate according to claim 1, characterized in that: The weight ratio of the friction component to the lubricating component of the second and subsequent segments of the inner ring raw material is 0.1 to 0.2 higher than that of the previous segment.

3. The thermal deformation resistant gradient clutch friction plate according to claim 1, characterized in that: The addition amount of each element of the matrix component is adjusted to ensure that the difference in density and porosity between adjacent sections of the friction lining is less than 5%.

4. A method for manufacturing a gradient clutch friction plate resistant to thermal deformation, characterized in that: The specific steps include: 1) Raw material mixing: Calculate the area ratio of each section to obtain the total weight ratio of each section of raw materials, and weigh the matrix component, interface strengthening component, lubrication component and friction component of each section according to the designed ratio, and then mix the weighed raw powder of each section in a planetary ball mill or mixer for 8 to 24 hours to obtain the composite raw material of each section; 2) Cold pressing: Use a segmented feeder to evenly spread the mixed raw materials on the template surface in sections, then remove the segmented feeder to cold press the friction lining as a whole, with a pressure of 400 MPa, and keep the pressure for 3 minutes to obtain pressed powder tablets; 3) Hot pressing sintering: The pressed powder sheet and the core plate are stacked and placed in a sintering furnace for hot pressing. The heating temperature is set to 900-980°C and the pressing pressure is 2-2.5MPa. After hot pressing for 1-2 hours, the friction sheet product is obtained and cooled in the furnace. 4) Product processing and testing: The cooled friction plate products are machined to remove surface defects such as flash, polished, cleaned and dried, and the oil groove texture of the friction lining is processed to obtain the finished friction plate. Finally, the finished friction plate is quality tested, and qualified finished friction plates can be installed in the clutch for use.

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