Railway Pad

Abstract

To provide a rail pad that can more effectively maintain and demonstrate the sliding performance of rails. [Solution] The track pad 3 interposed between the tie plate 20 and the bottom surface of the rail 1 comprises a base plate portion 30 molded from a rubber material, a thin surface plate portion 31 fixed to the top surface of the base plate portion 30 and molded from a synthetic resin with a lower coefficient of friction than the top surface of the base plate portion 30, and a processed surface 32 formed at the contact point between the surface plate portion 31 and the bottom surface of the rail 1, with multiple protrusions 33 having apexes 33a on their top surfaces that are contact surfaces with the bottom surface of the rail 1, and the protrusions 33 are formed in a shape such that the horizontal cross-sectional area S increases as one moves vertically downward from the apexes 33a.

Description

[Technical Field]

[0001] The present invention relates to a technology for rail pads, and more particularly to a rail pad that is interposed between the top surface of a sleeper or a tie plate and the bottom surface of a rail. [Background technology]

[0002] Conventionally, railway tracks have had thin, elastic pads called track pads installed between the top of the sleepers or tie plates installed on the top of the sleepers or track slabs and the bottom of the rail. These track pads function as a buffer between the sleepers or tie plates and the rail, mitigating the load transmitted to the track components below the rail, such as the sleepers and track slabs, as the train moves, thereby protecting them and reducing vibrations and the associated noise generated on the track.

[0003] A well-known structure for this type of track pad is one in which a steel plate or synthetic resin plate is fixed to the top surface of a rubber material. Compared to track pads made of rubber alone, these track pads have the advantage of having less friction with the rail and are less likely to be dragged by the rail when the rail moves forward due to expansion and contraction caused by temperature fluctuations or forces received when accelerating or decelerating the train. Therefore, they are mainly used as track pads for high-speed railways that use long rails.

[0004] For example, a known conventional rail pad configuration is a rail pad with a synthetic resin plate, which has a base plate and a surface plate molded from a synthetic resin with a lower coefficient of friction than the upper surface of the base plate, as disclosed in Patent Documents 1 and 2. Compared to rail pads with steel plates, such rail pads with synthetic resin plates are lighter and have excellent sliding performance without a decrease in frictional resistance due to rust, so they can effectively prevent the rail pad from being dragged by the expansion, contraction, or flexion of the rail.

[0005] However, the above-mentioned conventional track pad configuration has the problem that it is unable to stably maintain and demonstrate the sliding performance of the rail due to the influence of wear particles generated by wear of the surface layer plate portion, which become caught between the surface layer plate portion and the bottom surface of the rail, etc. In this regard, according to the configuration disclosed in Patent Document 2, it is true that the formation of a machined surface with a fine uneven pattern on the top surface of the surface layer plate makes it possible to remove wear particles from the top surface of the surface layer plate portion and the bottom surface of the rail, but there has been a demand for a track pad configuration that can more effectively maintain and demonstrate the sliding performance of the rail by improving the contact area of ​​the surface layer plate with the bottom surface of the rail and the shape of the machined surface (convex portion), etc. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2019-199744 [Patent Document 2] Japanese Patent Publication No. 2022-158728 Summary of the Invention [Problem to be solved by the invention]

[0007] Therefore, an object of the present invention is to provide a rail pad that can more effectively maintain and demonstrate the sliding performance of the rail. [Means for solving the problem]

[0008] The problem to be solved by the present invention is as described above, and the means for solving this problem will now be described.

[0009] That is, in claim 1, a track pad interposed between the upper surface of a sleeper or a tie plate and the bottom surface of a rail comprises a base plate portion molded from a rubber material, a thin surface plate portion fixed to the upper surface of the base plate portion and molded from a synthetic resin having a lower coefficient of friction than the upper surface of the base plate portion, and a processed surface having a plurality of convex portions formed at the contact points between the surface plate portion and the bottom surface of the rail, with apexes formed on the upper surfaces as the contact surfaces with the bottom surface of the rail, and the convex portions are formed in a shape such that the horizontal cross-sectional area increases as it goes vertically downward from the apexes.

[0010] In claim 2, the convex portion is formed in the shape of a rectangular block in plan view, with inclined surfaces continuing from the top portion formed on the four peripheral edges.

[0011] In claim 3, the convex portion is formed so that the height of the four corner portions is lower than the peripheral edge portion.

[0012] In claim 4, the processed surface is formed so that the surface area of ​​the tops of the projections accounts for 20% to 60% of the total surface area of ​​the surface plate portion.

[0013] In claim 5, the processed surface has a plurality of grooves extending from one edge of the convex portion to the opposing edge, and arranged in a grid pattern in a plan view. [Effects of the Invention]

[0014] The effect of the present invention is that the sliding performance of the rail can be more effectively maintained and exhibited. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a front view showing a state in which a railway pad according to an embodiment of the present invention is inserted into a tie plate. [Figure 2] FIG. [Figure 3] FIG. 2 is a plan view of the rail pad. [Figure 4]FIG. 2 is a front view of the rail pad. [Figure 5] FIG. [Figure 6] FIG. 10 is an enlarged partial front cross-sectional view of the surface plate portion and the processed surface. [Figure 7] FIG. 2 is an enlarged plan view of a convex portion of a processed surface. [Figure 8] 8(a) is a cross-sectional view taken along the line AA in FIG. 7, and FIG. 8(b) is a cross-sectional view taken along the line BB in FIG. [Figure 9] 8A is a cross-sectional view taken along the line AA in FIG. 7 after wear, and FIG. 8B is a cross-sectional view taken along the line BB in FIG. [Figure 10] 10 is an enlarged photograph of a convex portion of a processed surface of a railway pad according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0016] Next, an embodiment of the invention will be described.

[0017] As shown in Figure 1, the track pad 3 of this embodiment is used by being interposed between the bottom surface of a rail 1 that is installed along the length of the track on a railway track and a tie plate 20 that constitutes a fastening device 2. The tie plate 20 is composed of a rectangular base 21 and a pair of shoulders 22, 22 that are integrally disposed on the upper surface of the base 21 and protrude substantially vertically upward, and is fixed onto the track slab with bolts 23 so that the width direction of the base 21 is aligned with the length direction of the track.

[0018] The shoulders 22 extend along the width direction of the base 21 (the front-to-rear direction on the paper in FIG. 1) and are provided parallel to each other at a specified distance. A rectangular bag-shaped variable pad 24, hardened by resin injection, is disposed on the upper surface of the base 21 between the shoulders 22. The rail pad 3 (described later) is placed on the upper surface of the variable pad 24, and the bottom surface of the rail 1 abuts against the upper surface of the rail pad 3 (surface plate portion 31) to fix the rail 1 in the placed state.

[0019] Leaf springs 25 are attached to shoulders 22 on both sides of the rail 1 placed on the base 21, with one end 25a overlapping the other end 25b. Mounting holes (not shown) are drilled in the leaf springs 25 where the one end 25a and the other end 25b overlap, and bolts 26 protruding upward from the shoulders 22 are inserted through the mounting holes and fastened by nuts 27. In this state, the bottom of the rail 1 is pressed from above at one end 25a toward the track pad 3, thereby positioning and fixing the rail 1 to the fastening device 2.

[0020] 2 to 4, the railway pad 3 of this embodiment comprises a base plate portion 30 molded from a rubber material, a thin surface plate portion 31 fixed to the upper surface of the base plate portion 30 and molded from a synthetic resin with a lower coefficient of friction than the upper surface of the base plate portion 30, and a machined surface 32 formed on the surface of the surface plate portion 31 that abuts against the bottom surface of the rail. The railway pad 3 of this embodiment is formed to a standardized shape that matches the tie plate 20, and the upper surface of the base plate portion 30 and the lower surface of the surface plate portion 31 are fixed together via a horizontal joint surface.

[0021] The substrate portion 30 is configured as a rubber plate of a predetermined thickness (6 mm to 12 mm) molded from a rubber material, and in this embodiment, as an example, it is configured to have a main body portion 30a that is rectangular in plan view and has predetermined set dimensions (for example, 140 mm x 180 mm to 200 mm in plan view) that is placed on the upper surface of the above-mentioned variable pad 24, and a protrusion portion 30b that has predetermined set dimensions (for example, 200 mm x 50 mm in plan view) that protrudes sideways from the longitudinal end of the main body portion 30a, so that the overall configuration is approximately H-shaped in plan view.

[0022] The main body 30a has a plurality of protrusions 30c formed on its underside, which extend linearly along the longitudinal direction of the rail 1 (the length direction of the track), and the protrusions 30c are configured to press against the upper surface of the variable pad 24, maintaining the pressure-contact state between the variable pad 24 and the track pad 3.

[0023] The overhanging portion 30b is formed so as to protrude from the base 21 and be able to engage with the shoulder 22 when the railway pad 3 is installed on the tie plate 20, and by sandwiching both ends of the shoulder 22 between the overhanging portions 30b on both sides, the railway pad 3 installed on the tie plate 20 is restricted from moving along the longitudinal direction of the rail 1.

[0024] Examples of raw rubbers used for the rubber material include known rubber types such as natural rubber (NR), isoprene rubber (IR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), chloroprene rubber (CR), ethylene-propylene rubber (EPM), ethylene-propylene-diene rubber (EPDM), and silicone rubber (Q).These raw rubbers are also compounded with various commonly used compounding agents such as fillers, vulcanizing agents, vulcanization accelerators, reinforcing agents, softeners, plasticizers, foaming agents, gelling agents, processing aids, and antioxidants.

[0025] The surface plate portion 31 is configured as a synthetic resin plate of a predetermined thickness (1 mm to 2 mm) molded from a predetermined synthetic resin, and is formed in a rectangular shape in plan view with predetermined set dimensions (for example, 140 mm × 280 mm to 300 mm in plan view) that covers the entire area of ​​the main body portion 30a and a portion of the overhang portion 30b in the longitudinal direction (length direction of the track) of the base plate portion 30. By arranging the surface plate portion 31 in this manner, the upper surface of the surface plate portion 31 abuts against the bottom surface of the rail 1 without the base plate portion 30 coming into contact with the rail 1.

[0026] The top surface of the surface plate portion 31 comes into contact with the bottom surface of the rail 1, and is therefore molded from a synthetic resin that has a higher surface hardness and a lower coefficient of friction than the top surface of the base plate portion 30. As the synthetic resin, a polyamide resin or polyester resin, which is a type of engineering plastic that has excellent mechanical strength and enhanced heat resistance, is used.

[0027] Polyamide resins as synthetic resins are excellent in impact resistance, friction and abrasion resistance, oil resistance, etc., and preferred examples include nylon 6 and nylon 6,6. Polyamide resins have a lower coefficient of friction (for example, 0.16 static friction coefficient and 0.14 dynamic friction coefficient for nylon 6) than steel plate (for example, 0.13 static friction coefficient and 0.20 dynamic friction coefficient for SUS430), making it easier for the rail 1 placed on the railway pad 3 to slide, and their specific gravity (for example, 1.14 for nylon 6) is lower than steel plate (for example, 7.75 for SUS430), allowing for the weight of the railway pad 3 to be reduced.

[0028] Polyester resins as synthetic resins have excellent mechanical properties, heat resistance, oil resistance, friction and wear resistance, moldability, etc., as well as low water absorption and dimensional stability, and polybutylene terephthalate (PBT) resin is a preferred example. Polyester resins have a low coefficient of friction against steel, allowing them to exhibit excellent sliding performance with the rail 1 placed on the track pad 3, and their specific gravity (e.g., 1.31 for polybutylene terephthalate resin) is lower than that of steel plate (e.g., 7.75 for SUS430), allowing for the weight of the track pad 3 to be reduced.

[0029] In particular, the track pad 3 of this embodiment is preferably configured as a track pad with a synthetic resin plate made of polyester-based resin. This configuration provides better dimensional stability against moisture absorption and water absorption than track pads with a synthetic resin plate made of polyamide-based resin, and prevents expansion and deformation of the surface layer plate portion 31 of the track pad 3. Therefore, the base plate portion 30 and the surface layer plate portion 31 do not easily peel off even when subjected to vibrations caused by the rail moving forward or trains passing during use.

[0030] Examples of polybutylene terephthalate resins that can be used include polybutylene terephthalate homopolymers obtained by homopolymerizing a dicarboxylic acid component (such as terephthalic acid) and a diol component (such as 1,4-butanediol), and polybutylene terephthalate copolymers obtained by copolymerizing terephthalic acid and 1,4-butanediol with a dicarboxylic acid component (such as dodecanedioic acid) and a diol component (such as polytetramethylene glycol or tetramethylene oxide glycol). These polybutylene terephthalate resins may be used alone or in combination of two or more.

[0031] Examples of polyester resins other than polybutylene terephthalate resin include polyethylene terephthalate (PET) resin, polynaphthalene terephthalate (PEN) resin, poly(1,4-cyclohexanedimethylene terephthalate) (PCT) resin, etc. These polyester resins may be added to the polybutylene terephthalate resin described above, or may be used alone or in combination of two or more.

[0032] 5 to 9, the processing surface 32 is formed at the contact point between the surface plate portion 31 and the bottom surface of the rail 1, and is configured with a fine convex pattern having a plurality of convex portions 33 with a flush horizontal surface. In this embodiment, the processing surface 32 has a plurality of convex portions 33 of uniform size formed over the entire surface of the surface plate portion 31.

[0033] The convex portions 33 are surrounded by a plurality of grooves 34 extending from one edge of the surface plate portion 31 to the opposing edge, forming a block-like convex pattern that is rectangular in plan view. The upper surfaces of the convex portions 33 are formed as smooth surfaces that are approximately square in plan view, and form the upper surface of the surface plate portion 31 as the processed surface 32.

[0034] The convex portion 33 has a horizontally shaped top portion 33a formed on its upper surface, which is the contact surface with the bottom surface of the rail 1, and the tops 33a of the multiple convex portions 33 are arranged flush with each other on the machining surface 32 so that they are positioned on the same plane, so that the machining surface 32 (surface plate portion 31) abuts horizontally against the bottom surface of the rail 1.

[0035] The convex portion 33 is formed in a shape such that the horizontal cross-sectional area S increases from the apex 33a toward the vertically downward direction of the surface plate portion 31. In this embodiment, the four peripheral edges 33b are formed with convexly curved inclined surfaces that gently curve from the apex 33a and continue, forming a generally trapezoidal shape in cross section (see FIG. 8, etc.). That is, the convex portion 33 is formed such that the area of ​​the apex 33a on the upper surface is smaller than the horizontal cross-sectional area S of the convex portion 33 and the area of ​​the generally square bottom surface in plan view. In particular, the convex portion 33 in this embodiment is formed such that, among the four peripheral edges 33b, four corner portions 33c are formed with inclined surfaces that gently curve from the apex 33a and continue, and the height of the four corner portions 33c is lower than the peripheral edges 33b (see FIG. 8(b), etc.).

[0036] The railway pad 3 of this embodiment is formed so that the height H of the protrusions 33 (the height from the bottom surface of the groove 34 to the apex 33a of the protrusion 33) gradually decreases due to surface wear of the surface plate portion 31 caused by friction with the bottom surface of the rail 1, and the surface area of ​​the apex 33a increases as the height H of the protrusions 33 decreases (see FIGS. 8 and 9). In this way, the surface area of ​​the apex 33a of the protrusions 33 increases as the surface wear of the protrusions 33 increases, and as the railway pad 3 is used, the contact area of ​​the surface plate portion 31 with the bottom surface of the rail 1, i.e., the contact area of ​​the apex 33a of the protrusions 33, can be increased.

[0037] The grooves 34 are provided with a plurality of vertical grooves 34a drilled along the length of the track and a plurality of horizontal grooves 34b drilled along the width of the track, intersecting the vertical grooves 34a, and are formed so that the protrusions 33 are arranged in a lattice pattern (matrix pattern) in a plan view in the grooves 34 (the vertical grooves 34a and the horizontal grooves 34b). The vertical grooves 34a extend to both end faces of the track in the length direction and are formed in parallel in the width direction at a predetermined interval. On the other hand, the horizontal grooves 34b extend to both end faces of the track in the width direction and are formed in parallel in the length direction at a predetermined interval.

[0038] The height H of the convex portions 33, the length L of one side of the convex portions 33, and the groove width W of the groove portions 34 of the machined surface 32 are appropriately selected according to the set dimensions of the surface plate portion 31. In the track pad 3 of this embodiment, the height H of the convex portions 33 is preferably formed to be at least 0.15 mm in consideration of surface wear of the surface plate portion 31, the length L of one side of the convex portions 33 (length L1 in the longitudinal direction of the track, length L2 in the lateral direction of the track) is formed in the range of 1.5 mm to 5.0 mm, and the groove width W of the groove portions 33 (groove width W1 of the vertical groove portions 33a, groove width W2 of the lateral groove portions 33b) is formed in the range of 0.2 mm to 1.0 mm.

[0039] Furthermore, to effectively ensure the sliding performance of the rail 1 on the track pad 3, the processed surface 32 is formed so that the surface area of ​​the apexes 33a of the convex portions 33 accounts for 20% to 60% of the total surface area of ​​the surface plate portion 31, preferably 20% to 40%. In this case, the surface area ratio of the apexes 33a of the convex portions 33 is regardless of the state of surface wear of the convex portions 33 that occurs with use of the track pad 3, including not only an unused state but also a worn state. If the surface area ratio of the apexes 33a is less than 20a%, the contact area of ​​the surface plate portion 31 with the bottom surface of the rail 1 is small, resulting in too low a resistance to the progression of the track pad 3. If the surface area ratio of the apexes 33a is more than 60%, the frictional resistance of the surface plate portion 31 is too high, preventing the sliding performance of the rail 1 from being effectively achieved.

[0040] The railway pad 3 can be manufactured by any known method, including vulcanization bonding of the unvulcanized base plate 30 and the surface plate 31, or bonding of the surface plate 31 to a vulcanization-molded base plate 30. For example, when using the vulcanization bonding method, a predetermined vulcanization adhesive is uniformly applied to the underside of the surface plate 31 in advance. Heat and pressure are then applied to a mold containing the unvulcanized base plate 30 and the surface plate 31. The vulcanization temperature (approximately 150°C to 200°C) and time (approximately 5 to 30 minutes) are controlled to adjust the vulcanization rate, thereby vulcanizing and molding the unvulcanized base plate 30. According to the vulcanization bonding method, the surface plate 31 is bonded to the base plate 30 during rubber vulcanization, resulting in a railway pad 3 in which the upper surface of the base plate 30 and the lower surface of the surface plate 31 are integrally bonded via a bonding interface.

[0041] The unvulcanized substrate portion 30 is prepared by mixing a predetermined raw rubber as the main component with various other compounding agents in predetermined amounts to prepare a rubber material, which is then thoroughly mixed using an internal mixer, open roll, or the like.

[0042] The surface plate portion 31 is formed by molding a predetermined synthetic resin using a known method (such as injection molding). The processed surface 32 of the surface plate portion 31 can be formed simultaneously with the injection molding or blow molding of the surface plate portion 31. In this case, a mold is used in which minute irregularities corresponding to the processing pattern of the convex portions 33 (and groove portions 34) of the processed surface 32 are formed in advance on the cavity surface by etching, sandblasting, or the like. [Example]

[0043] Examples of the present invention and comparative examples will be described below, but the present invention is not limited to the examples shown below.

[0044] <Preparation of sample body> For this example, a track pad with a synthetic resin plate was prepared (Example 1, base plate thickness: 10 mm, surface plate material: PBT plate (polyester resin), surface plate thickness: 1 mm, convex portion height H: 0.3 mm, convex portion side length L: 2.7 mm x 2.7 mm, groove width W: 0.3 mm). Additionally, a track pad with a steel plate (Comparative Example 1, base plate thickness: 10 mm, surface plate material: steel (SUS430)) and a track pad with a synthetic resin plate (Comparative Example 2, base plate thickness: 10 mm, PBT plate (polyester resin), surface plate thickness: 1 mm, no surface) were also prepared as comparative examples.

[0045] For the track pad with synthetic resin plate in Example 1, an unvulcanized base plate (static spring constant 58.8 MN / m) was prepared in accordance with the conventional JIS-E1117 "Buffer Track Pad." A vulcanizing adhesive (Chemlock 233X, manufactured by Lord Japan Inc.) was applied to a surface plate molded from polybutylene terephthalate (PBT) resin (Novaduran 5010R5, manufactured by Mitsubishi Engineering Plastics Corporation) and dried. The surface plate and base plate were then vulcanized in a mold at a vulcanization temperature of 160°C for 15 minutes to obtain a specimen.

[0046] As shown in Figure 10, the shape of the machined surface of the surface plate portion of the track pad with synthetic resin plate of Example 1 was confirmed from a surface photograph of the machined surface, and it was confirmed that the upper surface of the surface plate portion has a machined surface with a convex portion where the apex is formed as the contact surface with the bottom surface of the rail, and that the convex portion is formed in the shape of a rectangular block in plan view with continuous inclined surfaces from the apex formed on the four peripheral edges so that the horizontal cross-sectional area increases as it goes vertically downward from the apex, and that the height of the four corners is lower than the periphery.

[0047] <Sweeping resistance test and swept sliding test> In this example, in order to evaluate the sliding performance of the rail of the railway pad, a creep resistance test and a creep sliding test were carried out as follows.

[0048] In the buckling resistance test, a test rail mounted on a fastening device was loaded in the rail's longitudinal direction, and the buckling resistance, which is the load exerted when the test rail slid, was measured. The test method involved first attaching the above-mentioned test specimens (railway pads, Example 1 and Comparative Examples 1-2) to a fastening device (direct-connected 8-type 60, general-purpose), and fastening the test rail (with a clamping force of 59 N m) with the test rail placed on top of the rail pad to fix the test rail in position. A load was then applied to the test rail in the rail's longitudinal direction, and the buckling resistance (kN) was measured (n=3) based on the load and the rail's longitudinal displacement (distance: 10 mm).

[0049] In addition, in order to compare the change in the propagation resistance of the sample body due to surface wear of the convex parts of the surface plate, the propagation resistance test was performed not only on unused sample bodies, but also on sample bodies in which the convex parts of the surface plate had been surface worn after the propagation sliding test described below.

[0050] In the convergent sliding test, a test rail mounted on a fastening device was loaded in the rail longitudinal direction and slid horizontally at a predetermined frequency to wear down the machined surface (convex portion) of the track pad surface. The test method was similar to the convergent sliding resistance test described above: First, the test specimens (rail pads, Example 1 and Comparative Examples 1-2) were attached to a fastening device (direct-connected 8-type 60, general-purpose), and the test rail was placed on the top surface of the rail pad and fastened (clamping force: 59 N m) to fix the test rail in position. A load was then applied to the test rail in the rail longitudinal direction, and the test rail was slid horizontally over a sliding distance of 40 mm, 10,000 times, and at a frequency of 0.1 Hz to wear down the machined surface (convex portion) of the track pad surface (n=3).

[0051] [Table 1]

[0052] The results shown in Table 1 indicate that the track pad with synthetic resin plates of this example, in an unused state, exhibits a similar level of anti-friction force to the start pad with steel plates (Comparative Example 1), and that it exhibits superior rail sliding performance due to the smaller contact area of ​​the surface plate with the rail bottom compared to the track pad with synthetic resin plates without a processed surface (Comparative Example 2). Furthermore, after the anti-friction sliding test, when the convex portions of the surface plate were worn, the proportion of the surface area of ​​the tops of the convex portions to the total surface area of ​​the surface plate changed from 29% (unused state) to 55% (worn state). The corresponding change in anti-friction force (103%) was smaller than in Comparative Examples 1 (108%) and 2 (89%), confirming that the rail sliding performance was effectively maintained stably.

[0053] As described above, the railway pad 3 of this embodiment is interposed between the tie plate 20 and the bottom surface of the rail 1 and comprises a base plate portion 30 molded from a rubber material, a thin surface plate portion 31 fixed to the top surface of the base plate portion 30 and molded from a synthetic resin having a lower coefficient of friction than the top surface of the base plate portion 30, and a processed surface 32 formed where the surface plate portion 31 abuts against the bottom surface of the rail 1, with a plurality of protrusions 33 having apexes 33a on their top surfaces that form contact surfaces with the bottom surface of the rail 1. The protrusions 33 are formed in a shape such that the horizontal cross-sectional area S increases as they extend vertically downward from the apexes 33a, thereby more effectively maintaining and exhibiting the sliding performance of the rail 1.

[0054] That is, the track pad 3 of this embodiment, with its surface layer plate portion 31 molded from synthetic resin, is lighter than conventional track pads with steel plates, and has excellent sliding performance without a decrease in the resistance to curvature due to rust. Furthermore, the base plate portion 30 and the surface layer plate portion 31 do not easily separate even when subjected to rail curvature or vibrations caused by passing trains. Furthermore, the convex portions 33 formed on the processed surface 32 of the surface layer plate portion 31 allow wear particles generated by wear of the surface layer plate portion 31 to escape from the system via the top surface of the surface layer plate portion 31 and the bottom surface of the rail 1. Furthermore, the shape of the convex portions 33, which increases the horizontal cross-sectional area S, reduces the contact area with the bottom surface of the rail 1, thereby reducing the generation of wear particles. This suppresses changes in the resistance to curvature due to wear particles getting caught between the surface layer plate portion 31 and the bottom surface of the rail 1, and ensures stable sliding performance of the rail 1.

[0055] In particular, the rail pad 3 of this embodiment is formed in the shape of a rectangular block in plan view, with the convex portion 33 having inclined surfaces that continue from the apex 33b at the four peripheral edges 33b, thereby reducing resistance and catching on the bottom surface of the rail 1 and improving wear resistance (extending the service life), reducing the effect of wear powder and suppressing significant changes in the resistance to propagation, and enabling the sliding performance of the rail 1 to be maintained more stably.

[0056] Furthermore, in the convex portion 33, the height H of the four corner portions 33c is formed to be lower than the peripheral portion 33b, which improves the wear resistance (extends the lifespan) particularly in areas where resistance or snagging is likely to occur between the bottom surface of the rail 1, and makes it possible to maintain the sliding performance of the rail 1 more stably.

[0057] Furthermore, on the machined surface 32, the convex portions 33 are arranged in a grid pattern in a plan view with multiple grooves 34 extending from one edge to the opposing edge, so that wear powder from the surface plate portion 31 can be effectively released outside the system, improving the sliding performance of the rail 1.

[0058] The configuration of the rail pad 3 is not limited to the above-described embodiment, and various modifications are possible without departing from the scope of the present invention.

[0059] That is, in the above-described embodiment of the track pad 3, the groove portions 34 are formed on the machining surface 32 in a grid-like machining pattern when viewed from above. However, the machining pattern of the machining surface 32 is not limited to this, and it is also possible to adopt a machining pattern in which the groove portions 34 are formed only as a plurality of vertical groove portions 34a drilled along the length of the track, or a machining pattern in which the spacing between adjacent vertical groove portions 34a and horizontal groove portions 34c is varied.

[0060] Furthermore, in the above-described embodiment of the track pad 3, the base plate portion 30 is configured to have a substantially H-shaped configuration in plan view, with a main body portion 30a and a protruding portion 30b of predetermined set dimensions. However, the shape of the base plate portion 30 is not limited to this, and may be configured, for example, to have a rectangular shape in plan view without the protruding portion 30b, or a shape in which the protruding portion 30b protrudes outward from a portion of both longitudinal ends and is bent downward.

[0061] Furthermore, in the above-described embodiment of the track pad 3, the surface plate portion 31 is configured such that the synthetic resin plate integrally molded therewith is formed in a shape that covers part of the upper surface of the base plate portion 30, but the configuration of the surface plate portion 31 is not limited to this, and for example, the surface plate portion 31 may be formed by combining multiple synthetic resin plates, or may be formed in a shape that covers the entire surface of the base plate portion 30 (main body portion 30a and protrusion portion 30b). [Explanation of symbols]

[0062] 1 rail 2 Fastening device 3 Rail Pad 20 Thai Plate 21 Base 22 Shoulder 23 volts 24 Variable Pad 25 Leaf spring 25a one end 25b other end 26 volts 27 Nut 30 Circuit Board 30a Main body 30b Overhang 30c protrusion 31 Surface plate part 32 Machining surface 33 Convex part 33a Top 33b Periphery 33c Corner section 34 Groove

Claims

1. A track pad is installed between the top surface of the sleeper or the tie plate and the bottom surface of the rail. a base portion molded from a rubber material; a thin surface plate portion fixed to the upper surface of the base plate portion and made of synthetic resin having a lower coefficient of friction than the upper surface of the base plate portion; a processing surface having a plurality of convex portions formed at the contact points of the surface plate portion with the rail bottom surface, the convex portions having apexes on the upper surfaces thereof that are contact surfaces with the rail bottom surface; and The convex portion is formed in a shape such that the cross-sectional area in the horizontal direction increases as the convex portion extends vertically downward from the top portion. A railway pad characterized by:

2. 2. The rail pad according to claim 1, wherein the protrusion is formed in the shape of a rectangular block in plan view, with inclined surfaces continuing from the top of the protrusion formed on the four peripheral edges.

3. 3. The rail track pad according to claim 2, wherein the convex portion is formed so that the height of the four corners is lower than the height of the peripheral edge portion.

4. 3. The railway pad according to claim 1, wherein the processed surface is formed so that the surface area of ​​the tops of the convex portions accounts for 20% to 60% of the total surface area of ​​the surface plate portion.

5. 3. The rail pad according to claim 1, wherein the processed surface has a plurality of grooves extending from one edge of the protrusion to the opposing edge, the grooves being arranged in a grid pattern in a plan view.

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