A split brake shoe for a large-area rail vehicle and a design method

Abstract

This invention discloses a separate brake shoe and its design method for large-area rail vehicles. The brake shoe includes a friction element integrally formed at the bottom end of the back of the brake shoe. The friction element has a length of mm, and a groove is provided in the middle of the lower end of the friction element. The groove is U-shaped or V-shaped. Wear marking grooves are provided at the four corners of the friction element, and the position of the wear marking grooves near the back of the friction element is adjusted according to the visibility of the bogie structure. This invention provides a separate brake shoe and its design method for large-area rail vehicles. Through the structural design of the friction element, the groove design in the middle of the lower end of the friction element helps with heat dissipation and debris removal during braking, preventing heat accumulation and debris buildup from affecting braking performance. The wear marking grooves are designed as notches and integrally formed during hot pressing, which saves manufacturing costs and facilitates quick assessment of wear status during on-site maintenance, improving maintenance convenience.

Description

Technical Field

[0001] This invention relates to the field of rail transit technology, and in particular to a separate brake shoe for large-area rail vehicles and its design method. Background Technology

[0002] In the field of rail transportation, brake shoes, as a core component of the train braking system, directly affect the safety and stability of train operation. Traditional brake shoes are mostly of a single, integral structure, which has gradually revealed numerous problems over long-term use. Firstly, the wear of integral brake shoes is uneven across different areas; severe localized wear necessitates replacement of the entire shoe, resulting in significant material waste and increased operating costs. Secondly, their heat dissipation performance is limited. During high-speed or frequent braking, the heat generated by friction between the brake shoe and the wheel is difficult to dissipate quickly, causing a sharp rise in brake shoe temperature. This reduces the coefficient of friction, affects braking performance, and may even lead to thermal cracking and deformation, shortening the brake shoe's lifespan and posing a serious threat to train safety. Furthermore, the installation and disassembly of traditional brake shoes are complex, consuming significant manpower and time, hindering rapid train inspection and maintenance. With the continuous development of rail transportation, higher performance requirements are being placed on brake shoes, making the development of a new brake shoe structure with a large contact area and long lifespan an urgent need. This provides a new technical solution to address the aforementioned technical problems. Summary of the Invention

[0003] Based on this, it is necessary to provide a separate brake shoe and design method for large-area rail vehicles to address the above-mentioned technical problems. Through the structural design of the friction body, the groove design in the middle of the lower end of the friction body helps to dissipate heat and remove debris during braking, preventing heat accumulation and debris buildup from affecting braking performance. The wear indicator groove is designed in the form of a notch and is integrally formed during hot pressing, which not only saves manufacturing costs but also facilitates quick judgment of wear status during on-site maintenance, thus improving the convenience of operation and maintenance.

[0004] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0005] A type of split brake shoe for large-area rail vehicles, which is applied to the brake shoes of rail vehicles.

[0006] The aforementioned separate brake shoe for large-area rail vehicles and its design method, wherein the total length of the separate brake shoe for large-area rail vehicles is 2 × (200~250) mm, the radius of the arc of the separate brake shoe for large-area rail vehicles matches the wheel, and the diameter of the wheel includes at least 915 mm, including:

[0007] The bottom end of the back of the bearing is integrally formed with a friction body. The friction body is 200~250mm in length. A groove is provided in the middle of the lower end of the friction body. The groove is U-shaped or V-shaped. Wear marking grooves are provided at the four corners of the friction body. The position of the wear marking grooves near the back of the friction body is adjusted according to the visibility of the bogie structure.

[0008] The friction surface of the friction body has intersecting vertical and horizontal grooves to accelerate the break-in process during use.

[0009] Furthermore, the back of the tile is bonded to the friction body by hot pressing, and the back of the tile is provided with material gripping holes near both ends.

[0010] Furthermore, a cut is provided at the middle position of the lower end of the tile back, and the cut is determined according to the usage situation to determine whether it is necessary to make a complete cut.

[0011] Furthermore, the friction body is made of a high-friction synthetic polymer material, the backing material includes at least high-strength steel, and the thickness of the backing is not less than 4mm.

[0012] A design method for a split brake shoe for large-area rail vehicles includes at least the following steps:

[0013] S1: Reference inheritance, using the existing 352mm brake shoe nose, liner, and mounting hole position as the reference, keeping the interface parameters unchanged;

[0014] S2: Establish and analyze the length gradient simulation model. Establish at least four three-dimensional models of brake shoes with different lengths. Each model has a groove in the friction body. Combined with a wheel model with a diameter of 915mm, static simulation calculations are performed on each model under two brake shoe thrusts of 5kN and 25kN, with and without braking torque, to obtain the radial deformation of the brake shoe back, the radial deformation of the friction body, the brake shoe back stress, the maximum value of the contact pressure, the minimum value of the end contact pressure, and the contact pressure range parameters of each model.

[0015] S3: Multi-objective optimization and scheme selection. The optimal brake shoe length scheme is selected from the analysis results of step S2, based on the comprehensive criteria of the effective friction contact length ratio being greater than or equal to 70%, the back stress of the brake shoe being minimized, and the contact pressure difference being less than or equal to 0.45MPa.

[0016] S4: Process verification of the preferred solution: The preferred length solution selected in step S3 is produced in small batches and verified by bench or line tests to verify its average wear, whether hot spots occur and whether cracks appear on the back of the tile in actual use, so as to finally confirm the feasibility of the design solution.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a separate brake shoe and design method for large-area rail vehicles. Through the structural design of the friction body, the groove design in the middle of the lower end of the friction body helps to dissipate heat and remove debris during braking, preventing heat accumulation and debris buildup from affecting braking performance. The wear marking groove is designed in the form of a notch and is integrally formed during hot pressing, which saves manufacturing costs and facilitates quick judgment of wear status during on-site maintenance, thus improving the convenience of operation and maintenance. Attached Figure Description

[0019] To more clearly illustrate the solutions in this invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 A schematic diagram of the overall structure of the large-area separable brake shoe and design method for rail vehicles provided by the present invention;

[0021] Figure 2 A schematic diagram of the connection structure between the friction body and the back of the brake shoe for large-area rail vehicles and the design method provided by the present invention.

[0022] Figure 3 A schematic diagram of the vertical and horizontal grooves of the large-area rail vehicle split brake shoe and design method provided by the present invention;

[0023] Figure 4 The present invention provides deformation and stress curves of separate brake shoes of different lengths;

[0024] Figure 5 The friction body provided by this invention shows the trend of contact pressure variation along the length.

[0025] The markings in the diagram are explained as follows:

[0026] 1. Friction body; 2. Back of the bearing; 3. Groove; 4. Wear marking groove; 5. Horizontal groove; 6. Grip hole; 7. Cut; 8. Vertical groove. Detailed Implementation

[0027] To enable those skilled in the art to better understand the present invention, 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 merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0028] Example 1:

[0029] Please refer to Figure 1 - Figure 3 A design method for a split brake shoe for large-area rail vehicles, wherein the total length of the split brake shoe for large-area rail vehicles is 2 × (200~250) mm, the radius of the arc of the split brake shoe for large-area rail vehicles matches the wheel, and the diameter of the wheel is at least 915 mm, including:

[0030] The bottom end of the brake shoe 2 is integrally formed with a friction body 1, which is 200~250mm in length. This design ensures that the brake shoe and the wheel have sufficient contact area to achieve a reliable braking effect, and also facilitates operation and replacement during installation and maintenance.

[0031] A groove 3 is provided in the middle of the lower end of the friction body 1. The groove 3 is U-shaped or V-shaped, and its design has multiple functions. First, it helps to reduce the overall weight of the brake shoes, thereby reducing the energy consumption of the rail vehicle and improving operating efficiency. Second, during braking, the groove 3 can effectively dissipate heat and remove debris. During braking, the friction body 1 generates a large amount of heat due to intense friction with the wheel. The groove 3 can increase the airflow area, accelerate heat dissipation, and prevent the brake shoes from deteriorating or even being damaged due to heat accumulation. At the same time, the debris generated by friction can also be discharged in time through the groove 3, avoiding debris accumulation that affects braking performance and ensuring the stability and reliability of the braking process.

[0032] Wear marking grooves 4 are provided at each of the four corners of the friction body 1. The location of the wear marking grooves 4 near the back of the friction body 1 is adjusted according to the visibility of the bogie structure. Traditional brake shoes usually use marking lines to indicate the wear status, but this method has problems such as easy wear and unclear markings. In this embodiment, the marking is designed as a notch-shaped wear marking groove 4, which is integrally formed during hot pressing. This design not only saves manufacturing costs and eliminates the need for additional marking lines, but also allows maintenance personnel to quickly determine the wear status of the brake shoes by visually observing the wear of the wear marking grooves 4 during actual operation and maintenance, greatly improving the convenience of operation and maintenance and reducing maintenance time and workload.

[0033] The friction surface of the friction body 1 is provided with intersecting vertical grooves 8 and horizontal grooves 5 to accelerate the break-in process of the friction body 1 during use.

[0034] Furthermore, the backing plate 2 and the friction body 1 are bonded together by hot pressing. The backing plate 2 is provided with material gripping holes 6 near both ends. Before the friction body 1 is hot-pressed, these material gripping holes 6 can increase the adhesion between the friction body and the backing plate, making it more difficult for the friction body to separate from the backing plate, thus ensuring the molding quality and performance stability of the friction body 1.

[0035] Furthermore, a notch 7 is provided at the middle of the lower end of the brake shoe back 2. The notch 7 determines whether a complete cut is needed, depending on the usage. During the actual operation of the rail vehicle, the brake shoe may be modified according to different usage requirements. The design of the notch 7 can reduce the actual cutting width at the corresponding position of the brake shoe back 2. When cutting and modification are required, the operator can complete the cutting work more conveniently and quickly, improving the modification efficiency and reducing the modification difficulty and cost.

[0036] Specifically, the friction element 1 is made of a high-friction synthetic polymer material, giving it a high coefficient of friction, good wear resistance, and heat resistance. This provides stable and reliable friction during braking, effectively achieving the braking function. The brake shoe backing 2 is made of at least high-strength steel, possessing high strength, good toughness, and fatigue resistance, capable of withstanding the enormous tensile and impact forces generated during braking. Furthermore, the brake shoe backing 2 can be made of fiber material instead of steel, which reduces the weight of the brake shoe and the overall vehicle weight, increases the effective load capacity, and reduces the workload of maintenance personnel. Simultaneously, the thickness of the brake shoe backing 2 is not less than 4mm to ensure sufficient strength and rigidity, providing stable support for the friction element 1 and guaranteeing the overall structural stability and braking performance of the brake shoe.

[0037] Through the above structural design, the large-area rail vehicle's separate brake shoe and design method have advantages such as compact structure, firm connection, and stable braking performance. When the rail vehicle brakes, the friction body 1 generates friction with the wheel surface, converting the vehicle's kinetic energy into heat energy to achieve the braking purpose. The firm connection between the shoe back 2 and the friction body 1 ensures the effective transmission of braking force, ensuring the reliability and safety of the brake shoe, and can meet the braking requirements of rail vehicles under different operating conditions.

[0038] Example 2:

[0039] This embodiment, based on the above embodiments, specifically proposes a design method for a split brake shoe for large-area rail vehicles, which includes at least the following steps:

[0040] S1: Reference inheritance, using the existing 352mm brake shoe nose, liner, and mounting hole position as the reference, keeping the interface parameters unchanged;

[0041] S2: Establish and analyze the length gradient simulation model. Establish at least four three-dimensional models of brake shoes with different lengths. In each model, the friction body 1 is provided with a groove 3. Combined with a wheel model with a diameter of 915mm, static simulation calculations are performed on each model under two brake shoe thrusts of 5kN and 25kN, respectively, to obtain the radial deformation of the shoe back 2, the radial deformation of the friction body 1, the stress of the shoe back 2, the maximum value of the contact pressure, the minimum value of the end contact pressure, and the contact pressure range parameters of each model.

[0042] S3: Multi-objective optimization and scheme selection. The optimal brake shoe length scheme is selected from the analysis results of step S2, based on the comprehensive criteria of the effective friction contact length ratio being greater than or equal to 70%, the stress on the back of the brake shoe being minimized, and the contact pressure difference being less than or equal to 0.45MPa.

[0043] S4: Process verification of the preferred solution: The preferred length solution selected in step S3 is produced in small batches and verified by bench or line tests to verify its average wear in actual use, whether hot spots occur, and whether cracks appear on the back of the tile 2, so as to finally confirm the feasibility of the design solution.

[0044] Specifically, the dimensions of the split brake shoe structure are:

[0045] In this application, the length of the friction body 1 is preferably 230 mm, within the range of 200-250 mm. The combination of two 230 mm long brake shoes is also based on thorough analysis.

[0046] First, simulation results support this. Under braking torque conditions, the effective contact length ratio of the 2×230mm split brake shoe is better than that of the 2×235mm and 2×250mm schemes, demonstrating balanced and outstanding overall performance.

[0047] Secondly, the contact area has been significantly improved. The total friction surface area of ​​the two brake shoes reaches 368cm², which is 53.33% larger than the existing LH2 brake shoes. Moreover, the ratio of its arc length to the circumference of a 915mm diameter wheel reaches 16.18%, which can fully exert the braking performance and meet the design intention of large contact area.

[0048] Third, structural reliability is fully guaranteed. We have adopted the mature lug structure and liner welding structure of the LH1 type brake shoe to ensure stability during installation and use, avoid risks caused by structural innovation, and achieve a balance between innovative breakthroughs and reliability.

[0049] In the design of the wear line markings for the split brake shoes, we optimized the markings to be in the form of notches and integrally formed during hot pressing. This not only saves manufacturing costs but also facilitates quick judgment of the wear status during on-site maintenance, improving the convenience of operation and maintenance.

[0050] Material and thickness selection for roof tiles:

[0051] Regarding the material for the brake shoe backing, the traditional Q235B material was abandoned—because this material has a low safety factor and poses a risk of breakage during field application. Instead, QStE420TM hot-rolled high-strength steel, recommended by the TJ / CL592-2022 standard, was adopted. This steel has a yield strength ≥420MPa, a tensile strength of 480-620MPa, and significantly better fatigue resistance than Q235B, providing a solid guarantee for the long-term, high-load operation of the brake shoe.

[0052] In terms of thickness design, based on simulation optimization results, the thickness of the backing tile 2 is 4mm, which ensures structural strength while achieving lightweight design.

[0053] Specifically, the torque-free simulation analysis aims to optimize the brake shoe structure, increase the contact area between the brake shoe friction element and the wheel, and reduce the braking energy per unit area of ​​the friction element. By systematically analyzing the static characteristics of single and split brake shoes of different lengths on the wheel, the deformation and stress patterns of the brake shoe back and friction element under different brake shoe pressures are explored, providing a theoretical basis for optimizing brake shoe length and friction element performance.

[0054] The torque simulation analysis aims to systematically analyze the static characteristics of single brake shoes and split brake shoes of different lengths on wheels by applying torque to the surface of the brake shoe friction body, and to explore the effect of torque on the deformation, force law and contact pressure distribution of the brake shoe back and friction body.

[0055] No braking torque: This application uses the Solidworks 2020 and Ansys 2022 simulation platform to compare the force on the wheel of single brake shoes of different lengths.

[0056] There is braking torque:

[0057] Separable brake shoe length 2×230mm, wheel diameter Ø915mm

[0058] When the brake shoe length is 2×230mm, the maximum radial deformation of the shoe back is 0.0743mm, the maximum radial deformation of the friction element is 0.0660mm, the maximum stress on the shoe back is 22.008MPa, the maximum contact pressure of the friction element is 0.9907MPa, and the minimum contact pressure at the end of the friction element is 0.1946MPa. The simulation contour map is shown below. Figures 4-5 As shown.

[0059] Pressure distribution between brake shoe and wheel tread:

[0060] Table 1-2 and Figure 4This presents simulation results and graphs of deformation, stress, and contact pressure of separate brake shoes of different lengths under a brake shoe pressure of 5 kN. As the brake shoe length increases from 2×230 mm to 2×250 mm, the radial deformation of the shoe back decreases from 0.0743 mm to 0.0716 mm, the radial deformation of the friction body decreases from 0.0660 mm to 0.0638 mm, the stress on the shoe back first increases from 22.008 MPa to 23.817 MPa and then decreases to 19.880 MPa, and the maximum contact pressure of the friction body decreases from 0.9907 MPa to 0.9490 MPa. The contact pressure difference is smallest when the brake shoe length is 2×235 mm.

[0061] Table 1-2 Static simulation results of separate brake shoes of different lengths under brake shoe pressure K=5kN

[0062]

[0063] Tables 1-3 show the trend and proportion of contact pressure along the length of the brake shoe friction element, respectively. The trend indicates that as the brake shoe length increases, the proportion of paths with contact pressure > 0.1 MPa gradually decreases, from 62.67% to 58.43%, reaching its maximum when the brake shoe length is 2 × 230 mm. Under the influence of frictional torque, the overall contact pressure on the right side of the friction element is greater than that on the left side.

[0064] Table 1-3 Distribution of Path Contact Pressure Percentage

[0065] project unit 352mm 2×230mm 2×235mm 2×250mm Total path length mm 311.74 371.02 381.17 411.72 >0.1MPa path length mm 226.50 232.51 234.01 240.58 percentage % 72.66 62.67 61.39 58.43

[0066] The results shown in Tables 1-2 and 1-3 indicate that the effective contact length of the 2×230mm brake shoe is slightly longer than that of the 2×235mm brake shoe, but the range of contact pressure is greater than that of other brake shoes. Comparing the maximum stress on the back of the brake shoe, the maximum stress on the back of the 2×230mm brake shoe is 22.008 MPa, which is 7.59% lower than that of the 2×235mm brake shoe. Compared with the existing brake shoe's maximum stress of 56.827 MPa, the maximum stress reduction of the 2×230mm brake shoe is 61.27%.

[0067] Table 1-4 Distribution of Path Contact Pressure Percentage

[0068] project unit 352mm 2×220mm 2×230mm 2×235mm 2×250mm Total path length mm 155.87 175.38 185.51 190.58 205.86 >0.1MPa path length mm 155.87 175.38 185.51 190.58 205.86 percentage % 100.00 100.00 100.00 100.00 100.00

[0069] The results shown in Tables 1-2 and 1-3 indicate that the effective contact length of the 2×230mm brake shoe is comparable to that of brake shoes of other lengths, but the range of contact pressure is higher than that of the 2×235mm and 2×250mm brake shoes. Comparing the maximum stress on the back of the brake shoe, the maximum stress on the back of the 2×230mm brake shoe is 77.034 MPa, which is 5.04% higher than that of the 2×235mm brake shoe. Compared with the existing brake shoe's maximum stress of 118.89 MPa, the maximum stress reduction of the 2×230mm brake shoe is 35.21%.

[0070] The pressure distribution between the brake shoe and the wheel tread, with a wheel diameter of Ø915mm (both brake shoe and wheel), is shown in Table 1-5, which depicts the deformation and stress curves of separate brake shoes of different lengths under a brake shoe pressure of 25kN. As the brake shoe length increases from 220mm to 250mm, the radial deformation of the shoe back decreases from 0.1257mm to 0.1122mm, the radial deformation of the friction body decreases from 0.1188mm to 0.1060mm, the stress on the shoe back increases from 75.547MPa to 77.034MPa and decreases to 69.645MPa, and the contact pressure of the friction body decreases from 2.2578MPa to 1.9143MPa.

[0071] Table 1-5 Static simulation results of separate brake shoes of different lengths under brake shoe pressure K=25kN.

[0072]

[0073] Table 1-6 Distribution of Path Contact Pressure Percentage

[0074] project unit 352mm 2×230mm 2×235mm 2×250mm Total path length mm 311.74 371.02 381.17 411.72 >0.1MPa path length mm 297.13 371.02 381.17 411.72 percentage % 95.31 100.00 100.00 100.00

[0075] The results shown in Tables 1-5 and 1-6 indicate that the effective contact length of the 2×230mm brake shoe is the same as that of brake shoes of other lengths, but the range of contact pressure is higher than that of the 2×235mm and 2×250mm brake shoes. Comparing the maximum stress on the back of the brake shoe, the maximum stress on the back of the 2×230mm brake shoe is 54.69 MPa, which is 6.06% lower than that of the 2×235mm brake shoe, but far lower than the yield strength of 235 MPa. Compared with the existing brake shoe's maximum stress of 116.23 MPa, the maximum stress reduction of the 2×230mm brake shoe is 52.95%.

[0076] Simulation analysis conclusions:

[0077] Without braking torque, the back stress of the 2×235mm separate brake shoe is lower than that of the 2×220mm and 2×230mm brake shoes, and the contact pressure difference is the smallest, with a more uniform contact pressure distribution. However, the effective contact length is slightly shorter than that of the 2×230mm brake shoe. With braking torque, the effective contact length of the 2×230mm separate brake shoe is better than that of the 2×235mm and 2×250mm brake shoes, and the back stress is lower than that of the 2×235mm brake shoe. Therefore, the length of the separate brake shoe should be 2×230mm.

[0078] Under the influence of frictional torque, the overall contact pressure on the right side of the friction body is greater than that on the left side.

Claims

1. A split brake shoe for large-area rail vehicles, wherein the total length of the split brake shoe is 2 × (200~250) mm, the radius of the arc of the split brake shoe matches the wheel, and the diameter of the wheel is at least 915 mm, characterized in that, include: The bottom end of the back of the corrugated frame (2) is integrally formed with a friction body (1). The friction body (1) is 200~250mm long. A groove (3) is provided in the middle of the lower end of the friction body (1). The groove (3) is U-shaped or V-shaped. Wear marking grooves (4) are provided at the four corners of the friction body (1). The wear marking grooves (4) are located near the back of the friction body (1) and are adjusted according to the visibility of the bogie structure. The friction surface of the friction body (1) is provided with intersecting vertical grooves (8) and horizontal grooves (5) to accelerate the break-in of the friction body (1) during use.

2. The split brake shoe for large-area rail vehicles according to claim 1, characterized in that, The back of the tile (2) and the friction body (1) are bonded together by hot pressing. The back of the tile (2) is provided with material gripping holes (6) near both ends.

3. The split brake shoe for large-area rail vehicles according to claim 1, characterized in that, A cut (7) is provided at the middle position of the lower end of the tile back (2). The cut (7) is determined according to the usage situation to determine whether it needs to be completely cut.

4. The separate brake shoe and design method for large-area rail vehicles according to claim 1, characterized in that, The friction body (1) is made of a high-friction synthetic polymer material, and the backing material (2) includes at least high-strength steel, with a thickness of not less than 4 mm.

5. A design method for a split brake shoe for a large-area rail vehicle, used to design a single brake shoe for a large-area rail vehicle as described in any one of claims 1-4, characterized in that: At least the following steps are included: S1: Reference inheritance, using the existing 352mm brake shoe nose, liner, and mounting hole position as the reference, keeping the interface parameters unchanged; S2: Establish a length gradient simulation model and conduct analysis. Establish at least four different lengths of brake shoe three-dimensional models. The friction body (1) in each model is provided with a groove (3). Combined with a wheel model with a diameter of 915mm, static simulation calculations are performed on each model under two brake shoe thrusts of 5kN and 25kN, respectively, to obtain the radial deformation of the back of the brake shoe (2), the radial deformation of the friction body (1), the stress of the back of the brake shoe (2), the maximum value of the contact pressure, the minimum value of the end contact pressure, and the contact pressure range parameters of each model. S3: Multi-objective optimization and scheme selection. The optimal brake shoe length scheme is selected from the analysis results of step S2, based on the comprehensive criteria of the effective friction contact length ratio being greater than or equal to 70%, the minimization of the back stress (2) of the brake shoe, and the contact pressure difference being less than or equal to 0.45MPa. S4: Process verification of the preferred scheme: The preferred length scheme selected in step S3 is tested in small batches, and its average wear in actual use, whether hot spots are generated, and whether cracks appear on the back of the tile (2) are verified through bench or line tests, so as to finally confirm the feasibility of the design scheme.

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