Railway wheels

Abstract

To reduce thermal stress of a plate part generated in braking, and improve durability of a railway wheel.SOLUTION: A railway wheel (100) includes a boss part (10), a rim part (20), and a plate part (30). The boss part (10) constitutes an inner peripheral part of the wheel (100). The rim part (20) constitutes an outer peripheral part of the wheel (100). The rim part (20) includes a tread (21) and a flange (22). The plate part (30) connects the boss part (10) and the rim part (20). The plate part (30) is curved toward a side opposite to a side where the flange (22) is positioned in an axial direction. A distance (d1) between a boss width central line (L1) and a curved vertex (C) is larger than 40 mm. The boss width central line (L1) passes through a central position of the boss part (10) in the axial direction, and extends in a radial direction. The curved vertex (C) is an inflection point on a plate thickness central line (A) of the plate part (30), and is an inflection point where the plate thickness central line (A) is separated farthest away from the flange (22) in the axial direction.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to wheels (railroad wheels) used in railway vehicles. [Background technology]

[0002] Conventionally, tread brakes have been known as a type of braking device for railway vehicles. Many railway vehicles, particularly freight cars, use tread brakes as braking devices. Tread brakes press brake shoes against the treads of railway wheels to generate friction between the brake shoes and the treads. This brakes the rotation of the wheels or axles, slowing down or stopping the railway vehicle.

[0003] During braking by the tread brake, frictional heat is generated between the tread of the railway wheel and the brake shoe of the tread brake. This causes the temperature of the rim part, including the tread, to rise in the railway wheel, causing thermal expansion of the rim part. If the rim part is displaced due to thermal expansion, this affects the running stability of the railway vehicle. In particular, if the rim part is displaced in the axial direction of the wheel, this may induce meandering or derailment of the railway vehicle.

[0004] For example, Patent Document 1 proposes a shape of a railway wheel for reducing the displacement and thermal stress of the rim portion. In the wheel of Patent Document 1, a curved plate portion is provided between the rim portion on the outer periphery side and the boss portion on the inner periphery side. The plate thickness center line of this plate portion has inflection points on the rim portion side and the boss portion side, and a middle point (curvature apex) located between them. The angle between the tangent to the plate thickness center line at the inflection point on the rim portion side and the tangent to the plate thickness center line at the inflection point on the boss portion side is set to 90° to 120°. The tangent to the plate thickness center line at the curvature apex is parallel to a center plane including the boss width center line. According to Patent Document 1, the distance from the center plane to the curvature apex is preferably within a range of 20 mm to 30 mm.

[0005] Patent Document 2 also discloses a railway wheel having a curved plate portion. In the wheel of Patent Document 2, the plate thickness center line of the plate portion has an arc-shaped curve arranged on the rim portion side and an arc-shaped curve arranged on the boss portion side, sandwiching an intersection point between the plate thickness center line and a central plane including the boss width center line. These curves are symmetrical with respect to the intersection point. In Patent Document 2, this wheel shape is intended to reduce the displacement of the rim portion in the axial direction of the wheel. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Special Publication No. 2009-545484 [Patent Document 2] Japanese Patent Application Publication No. 10-29401 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, the frictional heat generated by the brake shoe of the tread brake being pressed against the railway wheel causes the temperature of the rim to rise, resulting in thermal expansion of the rim. On the other hand, the temperature rise in the plate is small, and thermal deformation is unlikely to occur. In the plate, tensile stress occurs due to the thermal expansion of the rim. The stress generated in the wheel due to the frictional heat between the brake shoe and the wheel is called brake thermal stress. For example, when a railway vehicle travels down a long slope and continuous braking is performed, the brake thermal stress generated in the wheel increases, and the load on the wheel increases. If thermal stress that exceeds the yield stress occurs in the plate, the plate may undergo plastic deformation and be damaged.

[0008] However, the railway wheels of Patent Documents 1 and 2 are designed mainly taking into consideration the displacement of the rim in the axial direction, and are not designed taking into consideration the thermal stress generated in the plate portion due to braking. Therefore, it is difficult to suppress the plastic deformation of the plate portion caused by the thermal stress in the wheels of Patent Documents 1 and 2. When designing a railway wheel, it is necessary to ensure the durability of the wheel by considering not only the displacement of the rim in the axial direction but also the thermal stress of the plate portion.

[0009] An object of the present disclosure is to reduce the thermal stress in the plate portion that occurs during braking and improve the durability of the railway wheel. [Means for solving the problem]

[0010] The wheel according to the present disclosure is a wheel (railroad wheel) used in a railway vehicle. The wheel includes a cylindrical boss portion, a rim portion, and an annular plate portion. The boss portion constitutes the inner periphery of the wheel. An axle of the railway vehicle is inserted into the boss portion. The rim portion constitutes the outer periphery of the wheel. The rim portion includes a tread surface and a flange. The tread surface contacts the head surface of the rail on which the railway vehicle runs. The flange is adjacent to the tread surface in the axial direction of the wheel, and protrudes outward beyond the tread surface in the radial direction of the wheel. The plate portion connects the boss portion and the rim portion. The plate portion curves in the axial direction to the side opposite to the side on which the flange is located. The axial distance from the boss width center line to the curvature apex is greater than 40 mm. The boss width center line is a straight line that passes through the center position of the boss portion in the axial direction in the longitudinal cross section of the wheel and extends in the radial direction. The curvature apex is a straight line that passes through the center of the plate thickness of the plate portion in the longitudinal cross section of the wheel, and is located on the plate thickness center line. point The plate thickness center line is located at the farthest position from the flange in the axial direction. point It is. Effect of the Invention

[0011] According to the present disclosure, it is possible to reduce the thermal stress in the plate portion that occurs during braking, and to improve the durability of the railway wheel. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a vertical cross-sectional view of a railway wheel according to an embodiment. [Diagram 2] FIG. 2 is a graph showing the maximum principal stress of the plate portion of each wheel analysis model. [Diagram 3] FIG. 3 is a schematic diagram showing deformation of the wheel analysis model. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] The inventors have thoroughly studied the shape of the railway wheel and found that the brake thermal stress generated in the plate portion can be reduced by curving the plate portion relatively greatly toward the anti-flange side. The anti-flange side refers to the side opposite to the side where the flange is located in a railway wheel in which the tread and the flange are arranged in the axial direction and provided on the rim portion. Based on this finding, the inventors have completed the railway wheel according to the embodiment.

[0014] The wheel according to the embodiment is a wheel (railroad wheel) used in a railway vehicle. The wheel includes a cylindrical boss portion, a rim portion, and an annular plate portion. The boss portion constitutes the inner periphery of the wheel. An axle of the railway vehicle is inserted into the boss portion. The rim portion constitutes the outer periphery of the wheel. The rim portion includes a tread surface and a flange. The tread surface contacts the head surface of the rail on which the railway vehicle runs. The flange is adjacent to the tread surface in the axial direction of the wheel, and protrudes outward from the tread surface in the radial direction of the wheel. The plate portion connects the boss portion and the rim portion. The plate portion curves in the axial direction to the side opposite to the side on which the flange is located. The axial distance from the boss width center line to the curvature apex is greater than 40 mm. The boss width center line is a straight line that passes through the center position of the boss portion in the axial direction in the longitudinal cross section of the wheel and extends in the radial direction. The curvature apex is a straight line that passes through the center of the plate thickness of the plate portion in the longitudinal cross section of the wheel, and extends in the radial direction. point The plate thickness center line is located at the farthest position from the flange in the axial direction. point (First configuration).

[0015] In the railway wheel according to the first configuration, the plate portion connecting the rim portion and the boss portion is curved in the axial direction of the wheel on the opposite side (anti-flange side) to the side where the flange of the rim portion is located. The curved apex of the plate thickness center line of this plate portion is located more than 40 mm away from the boss width center line in the axial direction. That is, the plate portion of the railway wheel according to the first configuration is curved more greatly toward the anti-flange side compared to the plate portion of the railway wheel of, for example, Patent Document 1. This makes it possible to alleviate the concentration of stress at the curved apex of the plate portion during braking of the wheel. This makes it possible to reduce the thermal stress generated in the plate portion and suppress the plastic deformation of the plate portion. This makes it possible to improve the durability of the wheel.

[0016] The axial distance from the boss width center line to the curve apex is preferably 135 mm or less (second configuration).

[0017] According to the second configuration, the axial distance between the apex of the curvature of the plate thickness center line of the plate portion and the center line of the boss width is limited to 135 mm or less. This prevents the plate portion from curving excessively toward the anti-flange side. This prevents the wheel from becoming too heavy or the wheel shape from becoming too complicated, making it difficult to manufacture the wheel. In addition, the strength of the plate portion against the radial load of the wheel can be ensured.

[0018] Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In each drawing, the same or corresponding components are denoted by the same reference numerals, and the same description will not be repeated.

[0019] [Railway wheel configuration] Fig. 1 is a longitudinal cross-sectional view of a wheel 100 according to this embodiment. A longitudinal cross-sectional view is a cross-section of the wheel 100 cut along a plane including the central axis X. Since the longitudinal cross-sectional view of the wheel 100 is symmetrical with respect to the central axis X, Fig. 1 shows only one side of the wheel 100 about the central axis X. In this embodiment, the direction in which the central axis X of the wheel 100 extends is referred to as the axial direction, and the radial direction of the wheel 100 is simply referred to as the radial direction.

[0020] 1, a wheel 100 is a wheel (railroad wheel) used for a railway vehicle. The wheel 100 includes a boss portion 10, a rim portion 20, and a plate portion 30.

[0021] The boss portion 10 has a generally cylindrical shape centered on the central axis X, and constitutes the inner periphery of the wheel 100. An axle of a railway vehicle (not shown) is inserted into the boss portion 10. In Figure 1, a boss width center line L1 is indicated by a two-dot chain line. The boss width center line L1 is an imaginary straight line that passes through the center position of the boss portion 10 in the axial direction and extends in the radial direction in a vertical cross-sectional view of the wheel 100.

[0022] The rim portion 20 has a roughly cylindrical shape centered on the central axis X, and constitutes the outer periphery of the wheel 100. The rim portion 20 is positioned radially outward of the boss portion 10. In Figure 1, the rim width centre line L2 is indicated by a two-dot chain line. In a longitudinal cross-sectional view of the wheel 100, the rim width centre line L2 is an imaginary straight line that passes through the axial centre of the rim portion 20 and extends radially.

[0023] The rim portion 20 includes a tread 21 and a flange 22. The tread 21 is provided on the outer peripheral surface of the wheel 100. In other words, the tread 21 is an annular surface facing outward in the radial direction. The tread 21 contacts the top surface of the rail on which the railway vehicle runs. The diameter of the tread 21 gradually increases toward the flange 22. The shape of the tread 21 is not particularly limited. The tread 21 may be, for example, a conical tread or an arc tread.

[0024] The flange 22 is adjacent to the tread 21 in the axial direction. The flange 22 is provided at one axial end of the rim portion 20. In this embodiment, the side on which the flange 22 is located in the axial direction is called the flange side, and the opposite side is called the anti-flange side. In other words, the front side of the wheel 100 is the anti-flange side, and the back side of the wheel 100 is the flange side. The flange 22 protrudes outward from the tread 21 in the radial direction. When the railway vehicle runs on rails, the flange 22 is positioned on the inside of the left and right rails.

[0025] The surface of the flange 22 is connected to the tread 21. The connecting portion between the surface of the flange 22 and the tread 21 is called a throat 23. The throat 23 is a curve including one or more types of circular arcs in a vertical cross-sectional view of the wheel 100, and smoothly connects the surface of the flange 22 to the tread 21.

[0026] The axial distance between the midpoint 231 of the curved throat 23 and the boss width center line L1 can be, for example, 0 mm to 10 mm. The midpoint 231 of the throat 23 may be located on the flange side or the anti-flange side of the boss width center line L1. In this embodiment, the midpoint 231 of the throat 23 is located on the anti-flange side of the boss width center line L1. Therefore, the rim width center line L2 is also located on the anti-flange side of the boss width center line L1.

[0027] The plate portion 30 has an annular shape and connects the boss portion 10 on the inner periphery side and the rim portion 20 on the outer periphery side. The plate portion 30 has a thickness that is smaller than the axial length (boss width) of the boss portion 10 and the axial length (rim width) of the rim portion 20 as a whole. The plate portion 30 has a surface 31 on the opposite flange side and a back surface 32 on the flange side. The inner peripheral ends of the surface 31 and the back surface 32 are connected to the outer peripheral surface 11 of the boss portion 10 via connecting portions 41a and 42a that are substantially arc-shaped in a vertical cross section. The outer peripheral ends of the surface 31 and the back surface 32 are connected to the inner peripheral surface 24 of the rim portion 20 via connecting portions 41b and 42b that are substantially arc-shaped in a vertical cross section.

[0028] The plate portion 30 is curved toward the opposite flange side. Therefore, the plate thickness center line A of the plate portion 30 is also curved toward the opposite flange side. The plate thickness center line A is an imaginary curve that passes through the center of the plate thickness of the plate portion 30. In other words, the plate thickness center line A passes through the middle between the front surface 31 and the back surface 32 of the plate portion 30, and extends from the boss portion 10 side to the rim portion 20 side while curving along the front surface 31 and the back surface 32.

[0029] boardThe point where the thickness center line A is furthest from the flange 22 in the axial direction is taken as the curvature apex C. The curvature apex C is located on the anti-flange side of the boss width center line L1. However, it is preferable that the curvature apex C does not protrude from the rim portion 20 on the anti-flange side. In other words, the curvature apex C is preferably located on the flange side of the front surface 25 of the rim portion 20. The axial distance d1 from the boss width center line L1 to the curvature apex C is greater than 40 mm. It is preferable that the distance d1 is 135 mm or less.

[0030] The curvature apex C is, for example, located at a position in the radial direction closer to the rim portion 20 than to the boss portion 10. The radial distance d2 from the inner peripheral surface 24 of the rim portion 20 to the curvature apex C is preferably 63 mm or more. The distance d2 is preferably set to 124 mm or less.

[0031] The angle θ that the plate thickness centerline A makes with the boss width centerline L1 can be set, for example, in the range of 15° to 75°, and preferably in the range of 38° to 75°. The angle θ is the angle between the boss width centerline L1 and a straight line L3 obtained by linearly approximating the portion of the plate thickness centerline A on the boss portion 10 side from the curved apex C.

[0032] [effect] In the wheel 100 according to this embodiment, the curved apex C of the plate thickness center line A of the plate portion 30 is located more than 40 mm away from the boss width center line L1 on the anti-flange side. That is, the plate portion 30 connecting the boss portion 10 and the rim portion 20 is curved significantly on the anti-flange side. This makes it possible to alleviate stress concentration at the curved apex C of the plate portion 30 when the wheel 100 is braked by the tread brake. This makes it possible to reduce thermal stress generated in the plate portion 30 and suppress plastic deformation of the plate portion 30. This makes it possible to improve the durability of the wheel 100.

[0033] In the wheel 100 according to this embodiment, the axial distance d1 from the boss width center line L1 to the curvature apex C of the plate thickness center line A of the plate portion 30 is preferably set to 135 mm or less. This prevents the plate portion 30 from curving excessively toward the anti-flange side. This makes it possible to suppress an increase in the weight of the wheel 100, and also makes it possible to easily manufacture the wheel 100 while avoiding a complicated shape of the wheel 100. Furthermore, by not curving the plate portion 30 excessively, the strength of the plate portion 30 against radial loads can be ensured.

[0034] In this embodiment, the radial distance d2 from the inner circumferential surface 24 of the rim portion 20 to the curved apex C of the thickness center line A of the plate portion 30 is preferably 124 mm or less. This makes it possible to more reliably reduce the thermal stress generated in the plate portion 30.

[0035] Distance d2 is preferably 63 mm or more. This makes it possible to prevent the radius of curvature of connection portion 41b on the anti-flange side between rim portion 20 and plate portion 30 from becoming too small. This prevents stress concentration from occurring at connection portion 41b, and reduces mechanical stress at connection portion 41b.

[0036] In this embodiment, the angle θ of the plate thickness centerline A relative to the boss width centerline L1 is, for example, 15° to 75°. By ensuring a sufficient angle θ, the connection portion 42a on the flange side between the boss portion 10 and the plate portion 30 becomes a gentle arc shape. Therefore, stress concentration is less likely to occur at the connection portion 42a, and the mechanical stress at the connection portion 42a can be reduced.

[0037] Although the embodiments of the present disclosure have been described above, the present disclosure is not limited to the above-described embodiments, and various modifications are possible without departing from the spirit of the present disclosure. EXAMPLES

[0038] The present disclosure will be described in more detail below with reference to examples, although the present disclosure is not limited to the following examples.

[0039] In order to evaluate the effect of the railway wheel according to the present disclosure, a numerical analysis was carried out using the finite element method (FEM analysis). In the analysis, an analytical model having the same shape as the wheel 100 shown in Fig. 1 was created, and the axial distance d1 from the boss width center line L1 to the curve apex C of the plate thickness center line A was changed to evaluate the thermal stress of the plate portion 30 and the axial displacement of the rim portion 20. For comparison, a similar evaluation was also carried out on the analytical model of the wheel shape disclosed in Patent Document 1.

[0040] The analysis was performed using general-purpose software (ABAQUS Ver.6.12, Dassault Systèmes). In the analysis, to simulate the braking of a railway vehicle by tread braking, the heat flux required to slow a vehicle with an axle load of 40 tons downhill was applied to the area of ​​the tread 21 that comes into contact with the brake shoe of the tread brake. The braking time was set to 1200 seconds, and the inner circumference of the wheel 100 was fully restrained. Other analysis conditions and analysis results are shown in Table 1 and Figure 2.

[0041] [Table 1]

[0042] [Thermal stress in plate] The thermal stress of the plate portion 30 was evaluated by the maximum principal stress of the plate portion 30 1200 seconds after the wheel 100 was given a heat flux. The maximum principal stress of the plate portion 30 shown in Table 1 is a ratio to the maximum principal stress of the wheel shape (No. 1) of Patent Document 1. As can be seen from Table 1, in the wheel shapes (No. 2 and No. 4) in which the distance d1 between the boss width center line L1 and the curved apex C of the plate thickness center line A is greater than 40 mm, the maximum principal stress of the plate portion 30 was significantly reduced compared to the wheel shape (No. 1) of Patent Document 1 in which the distance d1 is 35 mm. As shown in FIG. 2, when the distance d1 is 87 mm (No. 2), the maximum principal stress of the plate portion 30 was reduced by about 20% compared to the wheel (No. 1) of Patent Document 1, and when the distance d1 is 135 mm (No. 4), the maximum principal stress of the plate portion 30 was further reduced. On the other hand, in the wheel shape (No. 3) in which the distance d1 was 40 mm, the maximum principal stress of the plate portion 30 was approximately the same as that of the wheel shape (No. 1) of Patent Document 1.

[0043] [Displacement of rim] Fig. 3 is a schematic diagram showing deformation of a wheel caused by braking with the deformation amount being approximately 20 times. In Fig. 3, the outer shape of the wheel 100 before deformation is shown by a two-dot chain line, and the outer shape of the wheel 100 after deformation is shown by a solid line. In the analysis, the axial displacement of the rim portion 20 was evaluated by comparing the position P of the wear limit (use limit) on the flange side surface of the rim portion 20 before and 1200 seconds after the heat flux was applied to the wheel 100.

[0044] In Table 1, a positive displacement of the rim portion means that the rim portion 20 has been displaced toward the opposite side to the flange, and a negative displacement of the rim portion means that it has been displaced toward the flange. As can be seen from Table 1, the axial displacement of the rim portion for all wheels 100 was within the range (-1.0 mm to 3.0 mm) permitted by European Standard EN13979-1.

[0045] As described above, it was confirmed that the thermal stress generated in the plate portion 30 can be reduced by making the axial distance d1 from the boss width center line L1 to the curvature apex C of the plate thickness center line A greater than 40 mm. It was also found that when the distance d1 is greater than 40 mm, the axial displacement of the rim portion can also be suppressed. [Explanation of symbols]

[0046] 100: Wheels 10: Boss Section 20: Rim section 21: Tread 22: Flange 30: Board part L1: Center line of boss width A: Center line of plate thickness C: Curved apex

Claims

1. A wheel for use in a railway vehicle, a cylindrical boss portion that constitutes an inner periphery of the wheel and into which an axle of the railroad vehicle is inserted; a rim portion that forms an outer periphery of the wheel and includes a tread surface that contacts the head surface of a rail on which the railway vehicle runs, and a flange that is adjacent to the tread surface in the axial direction of the wheel and protrudes outward beyond the tread surface in the radial direction of the wheel; an annular plate portion that connects the boss portion and the rim portion and is curved in the axial direction opposite to the side where the flange is located; Equipped with when, in a longitudinal section of the wheel, a straight line that passes through a center position of the boss portion in the axial direction and extends in the radial direction is defined as a boss width center line, and a point on the plate thickness center line that passes through the plate thickness center of the plate portion and is located at a position where the plate thickness center line is farthest from the flange in the axial direction is defined as a curvature apex, the axial distance from the boss width center line to the curvature apex is 87 mm or more, a wheel, wherein an inner circumferential end of a front surface of the plate portion is connected to an outer circumferential surface of the boss portion on the opposite side of the boss width center line from the flange, and an inner circumferential end of a back surface of the plate portion is connected to the outer circumferential surface of the boss portion on the flange side of the boss width center line.

2. 2. A wheel according to claim 1, A wheel, wherein the distance in the axial direction from the boss width center line to the curvature apex is 135 mm or less.

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