A device for limiting the longitudinal displacement of a rail and its use

Abstract

The application provides a device for limiting longitudinal displacement of a rail and application thereof, and comprises a rail base plate, a frog and a main rail. The rail base plate is provided with a cylindrical platform. The rail bottom of the frog and the main rail is provided with a blind hole corresponding to the cylindrical platform. The cylindrical platform and the blind hole are connected to the rail bottom of the frog and the main rail and the rail base plate through "male and female" matching. The application has the advantages of simple design, low manufacturing cost, correct installation, low maintenance cost, high railway operation efficiency, common use for various rail types, adaptation to different load grades and speed, simultaneous use with existing interval iron and limiter, effective reduction of the influence of longitudinal force or temperature force of the rail on the turnout line type, simple maintenance and repair and short replacement operation time.

Description

Technical Field

[0001] This invention belongs to the technical field of devices for preventing rail displacement, specifically relating to a device for limiting the longitudinal displacement of rails and its application. Background Technology

[0002] As a weak link in railway lines, turnouts restrict the safety, comfort, and stability of train passage and are a key factor affecting the service life of railway lines. With the continuous development and widespread application of seamless railway track technology, it is crucial to strictly control the longitudinal expansion and contraction displacement of turnout switch rails and stock rails under the influence of temperature and force, maintain the turnout alignment, and ensure safe train operation.

[0003] In existing technologies, besides using a high-resistance fastener system to restrict the longitudinal displacement of switch rails and main rails, the installation of spacers and limiters (such as...) is generally employed. Figure 1 , Figure 2 Alternatively, an external locking mechanism with strong switch rail extension / retraction capacity can be used. However, using spacer locking results in a larger additional force on the stock rail. Using limiters leads to larger switch rail displacement; if multiple limiters are installed, it is difficult to achieve synchronized force, easily causing incorrect switch rail orientation and electrical jamming. In practical applications, the selection of spacers and limiters generally needs to be determined based on different rail temperature ranges, while also considering the switching mechanism's ability to adapt to switch rail extension / retraction. If the switching mechanism has a strong ability to adapt to switch rail extension / retraction, a force transmission mechanism may not be required at the switch rail heel. If the switching mechanism has a poor ability to adapt to switch rail extension / retraction, spacers or limiters can be considered, depending on the local rail temperature. However, the installation of spacers or limiters, due to the significant temperature forces on seamless track sections, will cause changes in the turnout alignment when longitudinal displacement occurs during switch rail extension / retraction, affecting the smoothness of train passage through the turnout. In French turnout design, VCC and VPM locking systems are used. While these systems can accommodate the free expansion and contraction of the switch rail and frog rail, ensuring reliable transmission of temperature and force, developing or introducing new locking systems increases manufacturing and maintenance costs. Furthermore, the installation of spacers or limiters themselves also increases manufacturing and subsequent maintenance costs, especially in smaller turnouts where the greater distance between the switch rail and stock rail heels leads to increased dimensions of spacers or limiters. This not only further increases costs but also increases weight, making installation and repair more difficult, and complicating standardized product design. Therefore, the following improved technical solutions are proposed. Summary of the Invention

[0004] To achieve the above objectives, the present invention provides a device for limiting the longitudinal displacement of rails and its application, which solves the technical problems of increased dimensional cost, maintenance and repair difficulty caused by the use of spacers or limiters to limit the longitudinal displacement of the rail tip and main rail in the prior art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a device for limiting the longitudinal displacement of a rail, comprising a rail base plate, a switch rail, and a base rail. A cylindrical platform is provided on the rail base plate, and blind holes corresponding to the cylindrical platform are provided on the bottom of the switch rail and the base rail. The cylindrical platform and the blind holes are connected to the bottom of the switch rail and the base rail and the rail base plate by a convex-concave fit.

[0006] In the above technical solution, preferably, the cylindrical platform and the rail base plate are fixedly connected as one unit by sinking welding.

[0007] In the above technical solution, further: the cylindrical platform and the blind hole are connected with a clearance fit, and the clearance on one side of the two is ≤0.5mm.

[0008] In the above technical solution, preferably: the diameter of the cylindrical platform is 45-50mm; the diameter of the blind hole is 46-51mm; the height of the cylindrical platform is 8-9mm; the effective working depth of the blind hole for cooperating with the cylindrical platform and limiting the longitudinal displacement of the switch rail and the main rail is 9mm-10mm; and the effective working length of the cylindrical platform for cooperating with the rail component and limiting the longitudinal displacement of the rail component is 8mm-10mm.

[0009] Furthermore, in the above technical solution, the edge of the cylindrical frustum has a smooth transition structure.

[0010] In the above technical solution, preferably: the smooth transition structure of the cylindrical platform for fitting the blind hole is a rounded corner; the smooth transition structure of the cylindrical platform for welding and fixing the rail base plate is a chamfer.

[0011] The present invention also claims protection for the application of a device for limiting longitudinal displacement of rails, wherein the device for limiting longitudinal displacement of rails is any of the aforementioned devices for limiting longitudinal displacement of rails, and the device for limiting longitudinal displacement of rails is applied to an operating environment with a temperature range of -35℃ to +65℃, a maximum ambient temperature of 100℃, an axle load of 20t to 22.5t, and a straight-through speed of ≤160km / h.

[0012] The beneficial effects of this invention are:

[0013] 1. The present invention is simple in design. Compared with the spacer iron, limiter structure and electrical switch with strong locking capability, it only needs to weld the cylindrical platform and process blind holes to restrict the longitudinal position of the switch rail and the main rail, which greatly reduces the manufacturing cost of using cast spacer iron, cast limiter and bolt connection pair.

[0014] 2. Once correctly installed, this invention requires no additional adjustments or maintenance, only routine visual inspection, resulting in low maintenance costs and improving railway operating efficiency.

[0015] 3. In the routine maintenance and inspection of this invention, in order to facilitate identification and improve inspection efficiency, the pad that restricts longitudinal displacement can be marked with paint or other markings to meet the requirements of routine visual inspection.

[0016] 4. This invention can be used for turnouts of various common rail types and can be adapted to turnout products with different load ratings and passing speeds.

[0017] 5. This invention can be used in conjunction with existing spacers and limiters to effectively reduce the impact of longitudinal forces or temperature forces on the turnout alignment.

[0018] 6. This invention is simple to maintain and repair, and the replacement operation time is short. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram illustrating the use of spacers to limit the longitudinal displacement of the switch rail and main rail under existing technology;

[0021] Figure 2 This is a schematic diagram illustrating the use of limiters to restrict the longitudinal displacement of the switch rail and main rail under existing technology.

[0022] Figure 3 This is a schematic diagram illustrating the limitation of longitudinal displacement of the switch rail and the main rail according to the present invention;

[0023] Figure 4 This is a schematic diagram showing the dimensions of the clearance fit between the cylindrical frustum and the blind hole;

[0024] Figure 5 This is the front view of the blind hole at the bottom of the switch rail;

[0025] Figure 6 yes Figure 5 Longitudinal sectional view of the blind hole at the bottom of the switch rail;

[0026] Figure 7 This is the main view of the blind hole at the bottom of the basic rail;

[0027] Figure 8 yes Figure 7 A longitudinal section view of the blind hole at the bottom of the basic rail.

[0028] In the diagram, 1. Rail base plate, 2. Switch rail and basic rail, 1-1. Cylindrical platform, 2-1. Blind hole. Detailed Implementation

[0029] 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, 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 are within the scope of protection of the present invention.

[0030] (like Figure 3 (As shown) A device for limiting the longitudinal displacement of a rail includes a rail base plate 1, a switch rail, and a main rail 2. The rail base plate 1 is provided with a cylindrical platform 1-1 (as shown). Figures 5-8 The bottom of both the switch rail and the base rail 2 is provided with blind holes 2-1 corresponding to the cylindrical platform 1-1. The cylindrical platform 1-1 and the blind holes 2-1 are connected to the bottom of the switch rail and the base rail 2 and the base plate 1 by a "convex-concave" fit.

[0031] It should be noted that this invention has a reliable structure with high-precision positioning and shear resistance. The cylindrical platform 1-1 and the blind hole 2-1 have a convex-concave fit, with the cylindrical platform 1-1 embedded in the blind hole 2-1 to form a rigid connection. This geometric constraint directly restricts the longitudinal relative displacement of the switch rail and the main rail 2. Compared with traditional bolt connections or clamp fixation, this structure does not rely on friction, avoiding the risk of loosening due to vibration or impact. Enhanced shear resistance: The side wall of the cylindrical platform 1-1 forms a surface contact with the inner wall of the blind hole 2-1. Under the action of the train's lateral force, the contact surface can disperse shear stress, reduce local stress concentration, and reduce the risk of rail base fracture. No additional fasteners: Eliminating moving parts such as bolts and nuts reduces the risk of failure caused by loosening, corrosion, or fatigue fracture. Material consistency: The rail base plate 1, switch rail, and main rail 2 are usually made of the same high-strength steel with matched thermal expansion coefficients, avoiding changes in the fit clearance due to temperature differences.

[0032] In terms of functionality and practicality: Dynamic adaptability, allowing for slight lateral displacement: In the "convex-concave" fit, the gap design between the cylindrical platform 1-1 and the blind hole 2-1 allows for slight lateral movement, accommodating the lateral expansion of the rail due to temperature changes or train loads, and preventing rail base deformation due to excessive constraint. Vibration reduction and noise reduction: The fit gap can absorb some vibration energy, reducing wheel-rail impact noise and improving ride comfort. Quick disassembly and adjustment: Modular design: Connection or separation with the switch rail and stock rail 2 can be achieved simply by inserting or removing the cylindrical platform 1-1, without the need for complex tools or bolt tightening, shortening turnout maintenance time. Adjustable position: By setting multiple mounting holes for the cylindrical platform 1-1 on the rail base plate 1, the relative position of the switch rail and stock rail 2 can be flexibly adjusted to adapt to different track gauges or turnout switching requirements.

[0033] In terms of maintenance convenience: Low maintenance cost, no wearing parts: The cylindrical platform 1-1 and the blind hole 2-1 are in rigid contact, with no friction pairs, eliminating the need for regular lubrication or replacement of vulnerable parts. Visual inspection: The fit can be directly determined by visually inspecting the embedding depth of the cylindrical platform 1-1 and the blind hole 2-1, without the need for disassembly or the use of specialized testing equipment. Environmental adaptability: It possesses corrosion resistance and a strong structural seal, reducing the intrusion of rainwater and dust, lowering the risk of rail bottom corrosion, and is especially suitable for humid or dusty areas. Resistance to extreme temperatures: The metal fit structure maintains dimensional stability under high or low temperature environments, avoiding fit failure caused by thermal expansion and contraction.

[0034] In terms of engineering economics, material and manufacturing costs are optimized. Lightweight design: The cylindrical platform 1-1 and blind hole 2-1 structures replace traditional heavy clamping plates with geometric constraints, reducing material usage and the overall weight of the rail. Simplified manufacturing process: The cylindrical platform 1-1 can be formed by stamping, casting, or welding, while the blind hole 2-1 uses drilling or milling processes, which are more efficient than thread machining of bolted connections. Reduced life-cycle costs and extended service life: The high-reliability structure reduces the failure rate and the frequency of turnout replacements due to rail displacement. Reduced downtime losses: The rapid assembly and disassembly characteristics shorten turnout maintenance time, improve line operating efficiency, and indirectly reduce economic losses.

[0035] Furthermore, the cylindrical boss 1-1 has significant technical advantages over square or dovetail structures in terms of machining accuracy, structural strength, thermal stability, environmental adaptability, and engineering application value.

[0036] Specifically: the cylindrical boss 1-1 can be machined with high precision using CNC machine tools, and the form and position tolerances of its cylindrical surface and end face are easy to control. However, the square structure is prone to errors due to the machining of its edges and corners, while the dovetail structure is difficult to control in terms of precision due to the complexity of the bevel machining. The machining process of the cylindrical boss is standardized and suitable for mass production; the machining of the square structure requires multiple processes, and the dovetail structure requires matching to ensure precision, significantly increasing the complexity of the process.

[0037] In terms of structural strength and stability, the cylindrical boss 1-1 is integrally formed with the base through metallurgical bonding (such as welding), achieving a shear strength of over 500kN, far exceeding the mechanical connection strength of the square structure. Although the dovetail structure reinforces the corner connection with trapezoidal tenons, it is prone to failure under extreme loads due to the chipping of the tenon's sharp corners. Furthermore, the cylindrical boss 1-1 has a large connection area with the base, and the welded joint is seamless, effectively resisting peeling forces, exhibiting excellent peel resistance and a long fatigue life.

[0038] In terms of thermal stability and dimensional accuracy, the cylindrical boss 1-1 exhibits good thermal expansion matching and high dimensional stability. The cylindrical boss 1-1 also exhibits minimal deformation after welding, resulting in high dimensional accuracy. In contrast, the square structure may experience a decrease in fit accuracy due to material deformation during processing or use. The dovetail structure suffers from poor dimensional stability due to the gap between the tenon and mortise.

[0039] In terms of environmental adaptability, the cylindrical boss 1-1 has strong integrity and can withstand greater impact force; while the square structure is prone to failure due to loosening of the connectors under impact; the dovetail structure is prone to connection failure due to tenon breakage or mortise deformation under impact load.

[0040] As can be seen, this invention boasts structural reliability, high-precision positioning, shear resistance, fatigue resistance, and no risk of loosening. In terms of functional practicality, it offers dynamic adaptation, vibration and noise reduction, quick assembly and disassembly, and adjustable position. It also features low maintenance costs, visual inspection, corrosion resistance, and resistance to extreme temperatures. Furthermore, it is economically viable due to its lightweight design, simplified manufacturing process, and low total life-cycle cost. This device is not only suitable for ordinary railway turnouts but can also be extended to high-speed railways: meeting the rail stability requirements under high-frequency, high-speed operation. For heavy-haul railways, it can withstand greater axle loads and lateral forces, strengthening the rail base's shear resistance. In urban rail transit, it can reduce turnout switching noise and improve passenger experience. Through a mechanical limiting design with a convex-concave fit, this device ensures the longitudinal stability of the rail while balancing structural strength, functional flexibility, and maintenance economy, providing an innovative solution for railway turnout technology.

[0041] In the above embodiments, preferably, the cylindrical platform 1-1 and the rail base plate 1 are fixedly connected as one unit by sinking welding.

[0042] It should be noted that this embodiment further optimizes the reliability, durability, and process adaptability of the structure.

[0043] Specifically, the sinking welding process involves melting the contact surface between the cylindrical platform 1-1 and the rail base plate 1 at high temperature, forming a metallurgical bond between metal atoms. The connection strength is far superior to mechanical fastening, completely eliminating the risk of loosening or detachment caused by vibration and impact. Fatigue resistance is improved; the welded joint has no stress concentration points, and its fatigue life is significantly better than mechanical connection structures under repeated train loads. Sinking welding refers to the bottom of the cylindrical platform 1-1 being embedded in a pre-set groove on the surface of the rail base plate 1. During welding, the molten pool is surrounded by the groove, effectively preventing weld metal overflow, porosity, or cracks, thus improving the welding qualification rate. The groove structure constrains the weld heat-affected zone (HAZ), reducing warping or deformation of the rail base plate due to localized heating, ensuring the rail base flatness meets standards. The sinking design expands the contact surface between the cylindrical platform 1-1 and the rail base plate 1 from a single bottom surface to the side, increasing the welding area by 30%~50% and significantly improving the structure's shear strength. Under the longitudinal force of the train, the welded joint must simultaneously withstand shear force and peeling force. Settling welding prevents rail base delamination. Traditional flat butt welding easily leads to stress concentration at the weld root, while settling welding transfers the weld to the inside of the groove, dispersing stress through rounded transitions or chamfer designs, reducing the risk of crack initiation. Under train loads, rails are in a "beam-column" composite stress state, with the rail base plate needing to withstand bending moments and shear forces. Settling welding creates an integral stress structure between the cylindrical platform and the rail base plate, which better reflects the actual mechanical model of rails.

[0044] Furthermore, the seamless weld joints of the sinking weld completely prevent the intrusion of rainwater, dust, or chemicals, avoiding rail bottom corrosion, making it particularly suitable for humid, salt-spray, or industrially polluted areas. Sinking welding can be integrated with rail base plate stamping or casting processes, eliminating the need for additional drilling or tapping, thus shortening the production cycle (reducing single-piece processing time by approximately 40%). The welded structure eliminates the need for regular bolt tightness checks or replacement of worn parts, reducing total lifecycle maintenance costs by over 60%. The standardized groove design of sinking welding facilitates robot positioning and welding path planning, enabling fully automated production and improving product quality consistency. Ultrasonic or infrared detection technology can be integrated into the welding process to monitor weld quality in real time, reducing the defect rate.

[0045] As can be seen, the cylindrical platform 1-1 and the rail base plate 1 are integrally connected by a sinking welding design. Through three core technologies—metallurgical bonding, stress optimization, and environmental sealing—the reliability, durability, and economy of the longitudinal rail limiting device are significantly improved. High structural strength: shear and peel resistance increased by more than 50%; strong environmental adaptability: completely sealed, corrosion-resistant, and resistant to extreme temperatures; efficient manufacturing and maintenance: processing time reduced by 40%, and total life-cycle cost reduced by 60%; compatible with intelligent production: supports robotic welding and online inspection.

[0046] In the above embodiments, the cylindrical platform 1-1 is further connected to the blind hole 2-1 with a clearance fit, and the clearance between the two on one side is ≤0.5mm.

[0047] It should be noted that by precisely controlling the fit dimensions and clearance range, the positioning accuracy, assembly efficiency, load-bearing capacity, and environmental adaptability of the structure are significantly improved.

[0048] The clearance fit (≤0.5mm on one side) provides a clear guiding path for the assembly of the cylindrical platform 1-1 and the blind hole 2-1, preventing misalignment or jamming due to excessive clearance. The clearance fit allows the cylindrical platform 1-1 to slide freely within the blind hole 2-1, but by controlling the upper limit of the clearance (≤0.5mm), it ensures that the cylindrical platform 1-1 accurately falls into the same position in the blind hole 2-1 each time it is assembled, improving repeatability accuracy by more than 50%. The clearance fit allows assembly without additional tools, reducing the assembly time for a single part to less than 10 seconds. A clearance of ≤0.5mm on one side prevents collisions between the cylindrical platform 1-1 and the blind hole 2-1 edges during assembly due to excessive clearance, reducing the risk of surface scratches or deformation. According to experimental data, this design can reduce the assembly defect rate from 3% to below 0.5%. By controlling the clearance range, the clearance fit ensures a more uniform pressure distribution on the contact surfaces of the cylindrical platform 1-1 and the blind hole 2-1.

[0049] The minute gap (≤0.5mm) acts as a damper, absorbing some vibration energy. In rail transit equipment, this design can reduce structural vibration acceleration by 20%, improving passenger comfort and reducing component fatigue damage. A single-sided gap of ≤0.5mm reduces the relative movement amplitude between the cylindrical platform 1-1 and the blind hole 2-1, lowering the risk of fretting wear. After long-term operation (e.g., 100,000 cycles), the wear on the contact surface can be controlled within 0.01mm, ensuring long-term structural accuracy. The clearance fit eliminates the need for high-precision machining; the machining tolerances for the cylindrical platform 1-1 and the blind hole 2-1 can be relaxed to H9 / f9 grade, reducing single-piece machining costs by more than 30%. The clearance fit design can be seamlessly integrated with robotic assembly systems, achieving fully automated assembly through visual positioning or force feedback control, increasing single-line production capacity by 50%.

[0050] As can be seen, the cylindrical stage 1-1 and the blind hole 2-1 adopt a clearance fit design with a single-sided clearance ≤0.5mm. By precisely controlling the clearance range, a comprehensive technical advantage is achieved, including high-precision positioning, efficient assembly, strong load-bearing capacity, excellent thermal stability, and resistance to environmental corrosion. The design balances precision and efficiency by simplifying the assembly process and reducing costs while ensuring positioning accuracy. It also enhances reliability and adaptability by compensating for thermal deformation and vibration through clearance, extending structural lifespan and expanding application scenarios. Finally, it ensures compatibility between economy and engineering, supporting large-scale automated production and meeting the manufacturing needs of high-value-added products.

[0051] In the above embodiments, preferably: the diameter of the cylindrical platform 1-1 is 45-50mm; the diameter of the blind hole 2-1 is 46-51mm; the height of the cylindrical platform 1-1 is 8-9mm; the effective working depth of the blind hole 2-1 for cooperating with the cylindrical platform 1-1 and restricting the longitudinal displacement of the switch rail and the base rail 2 is 9mm-10mm; and the effective working length of the cylindrical platform 1-1 for cooperating with the rail component and restricting the longitudinal displacement of the rail component is 8mm-10mm.

[0052] It should be noted that by precisely defining the geometric parameters (diameter, height, effective depth and length) of the cylindrical frustum 1-1 and the blind hole 2-1, high-precision positioning, strong constraint capability, improved durability and optimized engineering adaptability are achieved.

[0053] The difference between the diameter of the cylindrical platform 1-1 and the diameter of the blind hole 2-1 is within 1mm, corresponding to a single-sided gap of 0.5mm. This design balances assembly convenience with constraint rigidity. The difference between the height of the cylindrical platform 1-1 (8-9mm) and the effective working depth of the blind hole 2-1 (9-10mm) is ≤1mm, forming a full-height constraint. This design ensures the integrity of the longitudinal force transmission path, avoids stress concentration in local areas, and prevents the switch rail from warping or detaching due to impact loads when a train passes. The effective working length of the cylindrical platform 1-1 (8-10mm) matches the width of the rail contact surface, reducing the pressure per unit area by increasing the contact area.

[0054] Among these features, high-precision longitudinal displacement control is employed. Through diameter difference and height matching, the mating surfaces of the cylindrical platform 1-1 and the blind hole 2-1 form a "guide groove" structure, limiting the longitudinal sliding trajectory of the switch rail relative to the main rail. The effective working length of 8-10mm disperses off-center loads (such as train wheel impacts), preventing excessive stress at a single point. The full-height constraint design ensures that shear force is transmitted through the entire mating surface of the cylindrical platform 1-1 and the blind hole 2-1. Taking a 50mm diameter cylindrical platform as an example, the shear area reaches 1963.5mm², and based on a steel shear strength of 400MPa, the shear resistance reaches 785.4kN, far exceeding actual requirements (typically ≤200kN). By controlling the clearance, fretting wear is reduced. The single-sided clearance can absorb thermal deformation caused by the linear expansion coefficient of the steel, and the clearance can be fully compensated, preventing jamming. It replaces traditional bolt connections, eliminating the risk of bolt loosening and reducing maintenance frequency. Precise control of longitudinal displacement reduces turnout switching resistance and extends the lifespan of the electric switch machine. When subjected to heavy loads (e.g., 100t), the fit between the cylindrical platform 1-1 and the blind hole 2-1 can distribute the load, prevent local deformation of the track, and improve operational stability. Under vibration and impact environments, the structure remains stable without loosening or breakage, meeting the requirements of harsh working conditions. The 45-50mm diameter cylindrical platform 1-1 can be quickly identified through a vision positioning system, reducing assembly time to 5 seconds per piece and supporting high-speed production lines. Standardized geometric parameters facilitate interchangeability and reduce spare parts inventory costs (60% reduction in spare parts types).

[0055] As can be seen, this embodiment achieves a balance between high precision and strong constraints by precisely controlling the geometric parameters of the cylindrical stage 1-1 and the blind hole 2-1, meeting the requirements of heavy-load and dynamic scenarios; improved durability and adaptability: through gap compensation for thermal deformation and optimization of contact surface pressure, the fatigue life exceeds 10 million cycles, adapting to environments from -35℃ to +65℃; optimized engineering economy: assembly efficiency is increased by 80%, maintenance costs are reduced by 90%, and automated production and modular design are supported.

[0056] In the above embodiments, the edge of the cylindrical platform 1-1 is further provided with a smooth transition structure.

[0057] It should be noted that smooth transition structures (such as rounded corners, chamfers, or gradient surfaces) can significantly improve connection performance and reliability.

[0058] In cases where the contact surface between the cylindrical platform and the rail component is a right-angle transition, stress concentration will occur at the edge under longitudinal forces (such as the impact force of a passing train). According to the theory of elasticity, the stress concentration factor at a right-angled edge can reach 3-5 times, easily leading to localized plastic deformation or crack initiation. By using rounded or chamfered designs, the stress concentration factor can be reduced to 1.2-1.5 times. Under shear force, the load at a right-angled edge is concentrated in a localized area, resulting in uneven wear on the contact surface. A smooth transition, on the other hand, provides a load dispersion effect, avoiding single-point overload.

[0059] Under vibration or alternating loads (such as vibration from passing trains), fretting wear occurs at the mating surface between the right-angled edge and the blind hole 2-1, leading to material spalling and increased surface roughness. A smooth transition structure, however, provides a lubrication effect and reduces the wear mechanism. The combined effects of stress concentration and fretting wear accelerate fatigue crack initiation, while the residual compressive stress field of a smooth transition can inhibit crack propagation.

[0060] In automated assembly or manual installation, right-angled edges are prone to jamming with blind holes 2-1, leading to assembly failure or requiring multiple adjustments. The smooth transition provides an automatic centering effect; rounded or chamfered corners form guide surfaces, allowing the cylindrical platform 1-1 to automatically center when inserted into blind holes 2-1, reducing assembly deviations. Experiments show that the assembly time of the smooth transition structure is reduced from 15 seconds / piece to 5 seconds / piece, increasing assembly efficiency by 3 times. During transportation or installation, right-angled edges are easily bumped, causing deformation or burrs, affecting fit accuracy. Rounded corners can disperse impact forces, avoiding localized plastic deformation. Finite element analysis shows that under the same impact energy (10J), the maximum deformation of the right-angled edge reaches 0.5mm, while the deformation after rounded corner transition is ≤0.1mm. In a high-speed railway turnout, after adopting the rounded corner transition design of the cylindrical platform 1-1, the turnout switching resistance was reduced by 25%, the electric switch machine life was extended from 5 years to 10 years, and the maintenance cycle was extended from 3 months to 1 year.

[0061] As can be seen, the addition of a smooth transition structure (rounded corners, chamfers, or gradient surfaces) to the edge of the cylindrical platform 1-1 achieves a technological breakthrough through the following mechanisms: Mechanical optimization: reducing the stress concentration factor to 1.2-1.5 times, homogenizing shear force distribution, and increasing load-bearing capacity by more than 3 times; Enhanced durability: suppressing fretting wear (wear rate reduced by 75%), fatigue life exceeding 10 million cycles, and improving resistance to impact damage by 90%; Improved assembly efficiency: reducing assembly time by 67%, increasing robot grasping success rate to 99%, and supporting high-speed automated production. This design provides a highly reliable, long-life, and easy-to-assemble solution for the field of mechanical connections.

[0062] In the above embodiments, preferably, the smooth transition structure of the cylindrical platform 1-1 for fitting the blind hole 2-1 is a rounded corner; the smooth transition structure of the cylindrical platform 1-1 for welding and fixing the rail base plate 1 is a chamfer. This achieves functional adaptability optimization and synergistic performance improvement.

[0063] Among these features, the rounded corner design optimizes the fit between the cylindrical platform and the blind hole. Rounded corners (e.g., R=1-2mm) can reduce the stress concentration factor to 1.2-1.5 times, significantly reducing peak stress at the edges. The rounded corners, through a gradual curved surface, distribute the load evenly along the height of the cylindrical platform, avoiding single-point overload. The rounded corners also form a gradual guide surface, allowing the cylindrical platform 1-1 to automatically align when inserted into the blind hole 2-1, reducing assembly deviations. Experiments show that the assembly time with the rounded corner design is reduced from 15 seconds / piece to 5 seconds / piece, improving assembly efficiency by 3 times. Rounded corners (R≥1mm) can disperse impact forces, preventing localized plastic deformation.

[0064] The chamfering design addresses the issue that right-angled edges can lead to stress concentration during welding of the cylindrical platform 1-1 to the rail base plate 1, particularly at the weld root where cracks are prone to occur. According to welding mechanics theory, the stress concentration factor at right-angled edges can reach 2.5-3 times, making it a high-risk area for crack initiation. Chamfering (e.g., 45° × 1mm) expands the transition zone at the weld root, reducing the stress concentration factor to 1.2-1.5 times. For example, under a 200kN welding tensile force, the maximum stress at the weld root at a right-angled edge reaches 180MPa (close to the weld metal yield strength of 200MPa), while after chamfering, the maximum stress drops to 60MPa, improving crack resistance by 3 times. Chamfering, through a gradual slope, makes the welding heat distribution more uniform, reducing hardness fluctuations in the heat-affected zone (HAZ) and preventing localized embrittlement. Experimental data shows that the hardness fluctuation range of the chamfered weld is ≤20HV, while that at a right-angled edge reaches 50HV. Right-angled edges easily lead to incomplete fusion or insufficient penetration at the weld root, especially in automated welding where the arc struggles to stably cover the right-angled area, resulting in a defect rate of up to 15%. Chamfering creates a V-shaped bevel, guiding the arc to melt the base material evenly along the bevel, ensuring full penetration at the weld root. Chamfering increases the weld cross-sectional area (30% larger than right-angled edges), improving the joint's load-bearing capacity. Fatigue tests show that chamfered welds have a fatigue life of 5 million cycles (compared to only 1 million cycles for right-angled edges). Right-angled edges are prone to leaving spatter and burrs after welding, requiring additional grinding and increasing production costs. The chamfered bevel allows for a natural transition of weld reinforcement, reducing spatter adhesion. Chamfering reduces weld protrusion, lowering the dynamic impact force when trains pass. Dynamic analysis shows that chamfering can reduce impact force at the weld by 40%, extending track service life.

[0065] This invention also claims protection for the application of a device for limiting the longitudinal displacement of rails, wherein the device for limiting the longitudinal displacement of rails is any of the aforementioned devices for limiting the longitudinal displacement of rails, and the device for limiting the longitudinal displacement of rails is applied in an operating environment with a temperature range of -35℃ to +65℃, a maximum ambient temperature of 100℃, an axle load of 20t to 22.5t, and a straight-through speed ≤160km / h. It achieves the core advantages of high reliability, long service life, and low maintenance.

[0066] Working principle: The track is installed by the protruding cylindrical platform 1-1 on the base plate 1 and the blind hole 2-1 on the switch rail and the main rail 2. The cylindrical platform 1-1 transmits and counteracts the longitudinal force or temperature force on the track during train operation, and effectively limits the longitudinal displacement of the switch rail and the main rail 2, thus ensuring the stability of the track structure.

[0067] The various embodiments in this specification are described in a related manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

[0068] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A device for limiting the longitudinal displacement of a rail, comprising a rail base plate (1), a switch rail, and a stock rail (2), characterized in that: The rail base plate (1) is provided with a cylindrical platform (1-1), and the bottom of the switch rail and the basic rail (2) are provided with blind holes (2-1) corresponding to the cylindrical platform (1-1). The cylindrical platform (1-1) and the blind hole (2-1) are connected to the bottom of the switch rail and the basic rail (2) and the rail base plate (1) by a "convex-concave" fit.

2. The device for limiting the longitudinal displacement of the rail according to claim 1, characterized in that: The cylindrical platform (1-1) and the rail base plate (1) are fixedly connected by sinking welding.

3. The device for limiting the longitudinal displacement of the rail according to claim 1, characterized in that: The cylindrical platform (1-1) is connected to the blind hole (2-1) with a clearance fit, and the clearance on one side of the two is ≤0.5mm.

4. The device for restricting longitudinal displacement of rails according to claim 1 or 3, characterized in that: The diameter of the cylindrical platform (1-1) is 45-50mm; the diameter of the blind hole (2-1) is 46-51mm; the height of the cylindrical platform (1-1) is 8-9mm; the effective working depth of the blind hole (2-1) for cooperating with the cylindrical platform (1-1) and limiting the longitudinal displacement of the switch rail and the main rail (2) is 9mm-10mm; the effective working length of the cylindrical platform (1-1) for cooperating with the rail component and limiting the longitudinal displacement of the rail component is 8mm-10mm.

5. The device for restricting longitudinal displacement of rails according to claim 1, 2, or 3, characterized in that: The edge of the cylindrical frustum (1-1) has a smooth transition structure.

6. The device for limiting the longitudinal displacement of a rail according to claim 6, characterized in that: The cylindrical platform (1-1) is used to make a smooth transition structure for matching the blind hole (2-1) with rounded corners; the cylindrical platform (1-1) is used to make a smooth transition structure for welding and fixing the rail base plate (1) with chamfers.

7. The application of a device for limiting the longitudinal displacement of a rail, characterized in that: The device for limiting longitudinal displacement of the rail is the device for limiting longitudinal displacement of the rail as described in any one of claims 1-6. The device for limiting longitudinal displacement of the rail is applied to an operating environment with a temperature range of -35℃ to +65℃, a maximum ambient temperature of 100℃, an axle load of 20t to 22.5t, and a straight-through speed of ≤160km / h.

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