Fastening springs used in rail fastening structures

Abstract

To provide a fastening spring made of a non-metal material, excellent in electrical insulation and corrosion resistance.SOLUTION: A fastening spring is for use in fastening rails to a tie plate made of a non-metal material. The fastening spring is made of a non-metal material and has an open hole through which a bolt inserted through the tie plate can be inserted. The fastening spring is convex upward along a width direction.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fastening spring used in a rail fastening structure for fastening a rail to a tie plate attached to a track slab or a sleeper. [Background technology]

[0002] When fastening rails of railways or the like to track slabs or sleepers, a rail fastening structure is used in which the rails are held in place by metal members such as leaf springs. Various such rail fastening structures are known, and for example, a rail fastening device described in Patent Document 1 is known.

[0003] That is, the rail fastening device described in Patent Document 1 has a tie plate fixed to the roadbed side, and a leaf spring fixed to this tie plate presses down from above to hold the rail. In this case, the end face of the leaf spring is positioned parallel to the longitudinal direction of the rail, and this end face presses directly against the upper surface of the rail bottom. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-123480 Summary of the Invention [Problem to be solved by the invention]

[0005] The tie plates and leaf springs used in conventional rail fastening devices are made of metal, and to prevent corrosion and ensure electrical insulation performance, insulating plates are inserted, the leaf springs are surface-treated, etc. Furthermore, in order to prevent the occurrence of transportation disruptions due to ground faults in return currents that occur due to the electrical insulation between the rail and the rail fastening device, it is desirable to improve the above-mentioned electrical insulation performance.

[0006] However, conventional rail fastening devices have a problem in that the tie plates and leaf springs are made of metal, and therefore short circuits can occur due to damage to the surface treatment of the leaf springs, such as thinning, breakage, or detachment of the leaf springs, making it difficult to completely prevent the occurrence of the above-mentioned transportation disruptions.

[0007] Furthermore, if the surface treatment of tie plates or leaf springs is damaged, the rails may break due to corrosion or electrolytic corrosion caused by those parts, so there is a demand to reduce the risk of such rail breakage to as close to zero as possible.

[0008] Therefore, the present invention has been made in consideration of the above problems, and aims to provide a fastening spring to be used in a rail fastening structure that uses a non-metallic material that has excellent electrical insulation and corrosion resistance and can reduce weight. [Means for solving the problem]

[0009] The fastening spring according to the present invention is a fastening spring for fastening a rail to a tie plate made of a non-metallic material, and the fastening spring is made of a non-metallic material and has a through hole through which a bolt inserted into the tie plate can be inserted. ,width It is curved so that it is convex upward along the direction The through-hole is formed as a long hole that is long in the width direction and has a diameter that decreases from the top to the bottom in the vertical direction in a vertical cross section. It is characterized by the following.

[0011] In the clamping spring according to the present invention, it is preferable that the non-metallic material is carbon fiber reinforced plastic.

[0012] In the fastening spring according to the present invention, it is preferable that the fastening spring has an arc-shaped end at one end in the width direction.

[0013] In addition, in the fastening spring according to the present invention, it is preferable that the fastening spring has carbon fiber reinforced plastic laminated thereon by winding a sheet of carbon fiber reinforced plastic in the width direction.

[0014] The above summary of the invention does not list all of the necessary features of the present invention, and subcombinations of these features may also constitute inventions. [Effects of the Invention]

[0015] The rail fastening structure according to the present invention has a tie plate and a fastening spring made of non-metallic materials, which makes it possible to realize a rail fastening structure with excellent electrical insulation and corrosion resistance. Furthermore, because these components are made of non-metallic materials, it is possible to reduce the weight. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a perspective view showing an overview of a rail fastening structure according to an embodiment of the present invention; [Figure 2] 1A and 1B are six-view diagrams and a cross-sectional diagram of a fastening spring used in a rail fastening structure according to an embodiment of the present invention. [Figure 3] 1 is a diagram showing a rail fastening structure according to an embodiment of the present invention, viewed from the rail extension direction; [Figure 4] 10 shows measurement results of fastening spring stress of the rail fastening structure according to the present embodiment. [Figure 5] 6 is a graph showing the results of a temperature characteristic test of a fastening spring of the rail fastening structure according to the present embodiment. [Figure 6] 6 is a graph showing a load-displacement curve during a tip spring characteristic test of a fastening spring of the rail fastening structure according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] Preferred embodiments for carrying out the present invention will be described below with reference to the drawings. Note that the following embodiments do not limit the inventions according to the claims, and not all of the combinations of features described in the embodiments are necessarily essential to the solution of the invention.

[0018] FIG. 1 is a perspective view showing an overview of a rail fastening structure according to an embodiment of the present invention, FIG. 2 is a six-sided view and a cross-sectional view of a fastener spring used in the rail fastening structure according to an embodiment of the present invention, FIG. 3 is a view showing the rail fastening structure according to an embodiment of the present invention seen from the rail extension direction, FIG. 4 is a measurement result of the fastener spring stress of the rail fastening structure according to this embodiment, FIG. 5 is a graph showing the result of a temperature characteristic test of the fastener spring of the rail fastening structure according to this embodiment, and FIG. 6 is a graph showing a load-displacement curve during a tip spring characteristic test of the fastener spring of the rail fastening structure according to this embodiment.

[0019] As shown in Figure 1, the rail fastening structure 1 according to this embodiment is attached to track slabs and sleepers positioned on a roadbed (not shown). The rail fastening structure 1 according to this embodiment includes a tie plate 10 made of glass fiber reinforced thermoplastic (FRTP), a non-metallic material attached to the track slabs and sleepers, a rail 2 placed on the tie plate 10 via a rail height adjustment pad 3 and a track pad 4, a fastening spring 20 that holds the lower part of the rail 2 from above, and a fastening bolt 33, a fastening nut 32, and an insulating washer 31 that secure the fastening spring 20.

[0020] 2, the fastening spring 20 is a member curved so as to be convex upward in the width direction, and is made of a non-metallic material such as glass fiber reinforced plastic (GFRP) or carbon fiber reinforced plastic (CFRP), for example, an epoxy resin mixed with carbon. Carbon fiber reinforced plastic has a particularly high Young's modulus and lower electrical conductivity than metals, making it suitable for use in the rail fastening structure 1 according to this embodiment.

[0021] A through hole 21 extending in the vertical direction is formed in the center of the fastening spring 20. The through hole 21 is formed as an elongated hole that is long in the width direction, and is formed so that the diameter decreases from top to bottom.

[0022] The widthwise ends of the fastening spring 20 have arcuate ends. The fastening spring 20 is constructed by winding a carbon fiber reinforced plastic sheet in the widthwise direction, with reinforcing fibers laminated on the cross section, and winding the carbon fiber reinforced plastic sheet in the widthwise direction makes it possible to form the arcuate ends. Furthermore, to improve electrical insulation and abrasion resistance, a glass fiber reinforced plastic layer may be formed on the outer layer of the carbon fiber reinforced plastic of the fastening spring 20.

[0023] As shown in Fig. 3, the rail fastening structure 1 according to this embodiment configured as described above has a tie plate 10 fixed onto a roadbed (not shown), and the rail 2 is held in place by the fastening spring 20 pressing from above with fastening bolts 33 and fastening nuts 32. At this time, the arc end 22 on the base end side of the fastening spring 20 is engaged with the engaging portion 12 so as to be rotatable around the laying direction of the rail 2, and the arc end on the other end side is attached so as to be freely adjustable in height.

[0024] In addition, the through hole 21 of the fastening spring 20 is formed so that its diameter decreases from top to bottom, thereby preventing interference between the fastening bolt 33 and the through hole 21 due to the rotation of the arc end on the other end as described above, and making it possible to reliably apply the elastic force of the fastening spring 20 to the rail 2.

[0025] In addition, in the rail fastening structure 1 according to this embodiment, the tie plate 10 is made of a non-metallic material, so it is possible to eliminate the insulating plate that is used in conventional rail fastening structures and is interposed between the tie plate and the roadbed.

[0026] Next, with reference to FIG. 4, the results of a performance test of the rail fastening structure 1 according to this embodiment will be described. The performance test was conducted under static and dynamic bidirectional loading conditions in accordance with the "Railway Structure Design Standards and Commentary: Track Structure" (hereinafter referred to as the "Track Standards"). The loading test was conducted assuming application to a JIS 60 kg rail, conventional line (fastening interval 625 mm), and track with a curve radius of 600 m or more, and the design action loads A and B were determined under a design axle load of 150 kN. Measurements were taken at positions I near one fixing bolt hole on the back surface of the tie plate, II near the other fixing bolt hole, III near one longitudinal end of the rail engagement groove on the top surface of the tie plate, and IV near the other longitudinal end.

[0027] As shown in Figure 4, the maximum stress generated in the fastening spring 20 of the rail fastening structure 1 according to this embodiment during loading was 57.1 MPa, which was confirmed to be sufficiently small compared to the tensile strength of carbon fiber reinforced plastic, which is 638 MPa.

[0028] The dynamic loading test was carried out under the same conditions as the static loading test, with the target number of repetitions being 10. 6 10 times. 6 After the repeated loading, the fastening bolts and nuts did not loosen, and no external abnormalities were observed.

[0029] Thus, the results of the static loading test and the dynamic loading test confirmed that the rail fastening structure 1 according to this embodiment has safety in terms of fatigue fracture.

[0030] Next, an electrical insulation resistance test was conducted on the rail fastening structure 1 according to the present embodiment in accordance with the track standard. The electrical insulation resistance test measured the electrical insulation resistance value under three conditions: no spraying (dry condition), spraying of tap water (rainfall condition), and spraying of 0.1% salt water (polluted condition). The results of the electrical insulation resistance test showed that the electrical insulation resistance value exceeded the design reference value of 1.6 kΩ specified in the track standard in all conditions, and was more than 20 times that of conventional rail fastening structures, even in the polluted condition among the test conditions. This confirmed that the rail fastening structure 1 according to the present embodiment has sufficiently high electrical insulation properties compared to conventional rail fastening structures.

[0031] Next, a description will be given of the results of a performance confirmation test of the fastening spring 20. The performance confirmation test was conducted to test the temperature characteristics and spring characteristics of the fastening spring 20.

[0032] (Temperature characteristics) Resin-based materials such as CFRP change their mechanical strength and other properties depending on the ambient temperature, softening at high temperatures and becoming brittle at low temperatures. On the other hand, the ambient temperature range in which the fastening spring 20 is used is expected to be between -20°C and 60°C, so the temperature characteristics of the tensile strength, tensile modulus, and flexural strength and flexural modulus, which are indicators of mechanical strength in this temperature range, were obtained.

[0033] As shown in Figure 5, the results of the temperature characteristic test showed that the tensile strength of the CFRP was 638 MPa at room temperature of 23°C, but tended to decrease at lower temperatures, with a minimum of 527 MPa at -20°C (a 17% reduction). On the other hand, the flexural strength was 462 MPa at room temperature of 23°C, but tended to decrease at higher temperatures, with a minimum of 439 MPa at 60°C (a 5% reduction). In this way, it was confirmed that the mechanical strength of CFRP is relatively little affected by temperature dependency.

[0034] (spring characteristics) The tip spring characteristic test for the fastening spring 20 was performed by fastening the rail with a jig simulating the seating surface shape of the tie plate 10, as shown in Figure 3, and then loading the rail at a test speed of 1 mm / min. The rail was positioned so that the seating surface was 8 mm, 18 mm, and 24 mm lower than the jig's fastening spring seating surface to evaluate the effect on tip spring characteristics of changes in the fastening spring's position, which are expected when adjusting the rail height during installation. The bolts were manually tightened to avoid applying axial force. In this test, a load range of 4 kN to 12 kN was repeatedly applied, and the tip spring constant was calculated from the displacement and load in the third load range of 4 kN to 12 kN. The relationship between load and displacement during the spring characteristic test is shown in Figure 6. As shown in Figure 6, the load-displacement curve for the fastening spring 20 exhibited hysteresis in the load range of 0 kN to 12 kN.

[0035] The measurement results of the tip spring characteristic test are shown in Table 1 below. The tip spring constant (calculated range 4 to 8 kN) was 8.0 MN / m at a rail position of 8 mm and 7.6 MN / m at 24 mm. As such, it was confirmed that the curved fastening spring 20 is less affected by changes in posture and can provide a stable fastening force that is not dependent on rail height. [Table 1]

[0036] As described above, in the rail fastening structure 1 according to this embodiment, the tie plate 10 and fastening spring 20 are made of non-metallic materials, which improves the electrical insulation performance between the rail and the support body, thereby reducing the risk of transportation disruptions such as return current ground faults caused by this electrical insulation.

[0037] Furthermore, in the rail fastening structure 1 according to this embodiment, the tie plate 10 is made of a non-metallic material, making it possible to reduce the weight compared to conventional tie plates.

[0038] Furthermore, the rail fastening structure according to the present embodiment has been described above in terms of a case in which the tie plate 10 is made of short glass fiber reinforced thermoplastic plastic and the fastening spring 20 is made of carbon fiber reinforced plastic, but the non-metallic materials are not limited to these and various conventionally known non-metallic materials may also be used. It is clear from the claims that such modified or improved embodiments are also included within the technical scope of the present invention. [Explanation of symbols]

[0039] 1 rail fastening structure, 2 rail, 3 height adjustment pad, 4 track pad, 10 tie plate, 20 fastening spring, 21 through hole, 22 arc end, 31 insulating washer, 32 fastening nut, 33 fastening bolt.

Claims

1. A fastening spring for fastening a rail to a tie plate made of a non-metallic material, The fastening spring is made of a non-metallic material; the fastening spring has a through hole through which the bolt inserted in the tie plate can be inserted, and is curved so as to be convex upward along the width direction, The fastening spring is characterized in that the through hole is formed as a long hole that is long in the width direction and has a diameter that decreases vertically from top to bottom in a vertical cross section.

2. The fastening spring according to claim 1, The fastening spring is characterized in that the non-metallic material is carbon fiber reinforced plastic.

3. The fastening spring according to claim 2, The fastening spring is characterized in that the widthwise end portion has an arc-shaped end.

4. The fastening spring according to claim 3, The fastening spring is characterized in that the carbon fiber reinforced plastic is laminated by winding a carbon fiber reinforced plastic sheet in the width direction.

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