JP2021109525A - Railway wheel - Google Patents

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

The present disclosure relates to wheels (railroad wheels) used in railroad vehicles.

Conventionally, a tread brake is known as a kind of braking device for a railway vehicle. In particular, many railroad vehicles, which are freight cars, use tread brakes as braking devices. The tread brake creates friction between the brake shoes and the treads by pressing the brake shoes against the treads of the railway wheels. This brakes the rotation of the wheels or axles and slows or stops the railcar.

During braking by the tread brake, frictional heat is generated between the tread of the railroad wheel and the brake shoe of the tread brake. Therefore, in the railway wheels, the temperature of the rim portion including the tread surface rises, and thermal expansion of the rim portion occurs. When the rim portion thermally expands and is displaced, the running stability of the railway vehicle is affected. In particular, if the rim portion is displaced in the axial direction of the wheel, meandering or derailment of the railway vehicle may be induced.

For example, Patent Document 1 proposes a shape of a railway wheel for reducing displacement and thermal stress of a rim portion. In the wheel of Patent Document 1, a curved plate portion is provided between the rim portion on the outer peripheral side and the boss portion on the inner peripheral side. The plate thickness center line of this plate portion has an inflection point on the rim portion side and the boss portion side, and an intermediate point (curved apex) arranged between them. The angle between the tangent line to the plate thickness center line at the inflection point on the rim portion side and the tangent line 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 curved apex is parallel to the center plane including the boss width center line. According to Patent Document 1, the distance from the central plane to the curved apex is preferably in the range of 20 mm to 30 mm.

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 includes an arcuate curve arranged on the rim portion side with the intersection of the center plane including the boss width center line and the plate thickness center line, and the boss portion side. It has an arcuate curve arranged in. These curves are symmetric with respect to the intersection. In Patent Document 2, the displacement of the rim portion in the axial direction of the wheel is reduced by such a wheel shape.

Special Table 2009-545484 Japanese Unexamined Patent Publication No. 10-29401

As described above, the frictional heat generated by pressing the brake shoes of the tread brake against the railroad wheels raises the temperature of the rim portion and causes thermal expansion of the rim portion. On the other hand, in the plate portion, the degree of temperature rise is small and thermal deformation is unlikely to occur. In the plate portion, tensile stress is generated due to the thermal expansion of the rim portion. The stress generated on the wheel by the frictional heat between the brake shoe and the wheel is called the brake thermal stress. For example, when a railroad vehicle travels on a long downhill and continuous braking is performed, the brake thermal stress generated on the wheels increases, and the load on the wheels increases. When a thermal stress exceeding the yield stress is generated in the plate portion, the plate portion may be plastically deformed and the plate portion may be damaged.

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

An object of the present disclosure is to reduce the thermal stress of the plate portion generated during braking and to improve the durability of railway wheels.

The wheels according to the present disclosure are wheels (railroad wheels) used in railway vehicles. The wheel includes a tubular boss portion, a rim portion, and an annular plate portion. The boss portion constitutes the inner peripheral portion of the wheel. The axle of the railroad vehicle is inserted into the boss portion. The rim portion constitutes the outer peripheral portion of the wheel. The rim portion includes a tread and a flange. The tread contacts the top surface of the rail on which the railroad vehicle travels. The flange is adjacent to the tread in the axial direction of the wheel and projects outward from the tread in the radial direction of the wheel. The plate portion connects the boss portion and the rim portion. The plate portion is curved in the axial direction opposite to the side where the flange is located. The axial distance from the boss width center line to the curved apex is greater than 40 mm. The boss width center line is a straight line extending in the radial direction through the central position of the boss portion in the axial direction in the vertical cross section of the wheel. The curved apex is an inflection point on the plate thickness center line passing through the plate thickness center of the plate portion in the vertical cross section of the wheel, and is an inflection point at the position where the plate thickness center line is the farthest in the axial direction from the flange. ..

According to the present disclosure, the thermal stress of the plate portion generated during braking can be reduced, and the durability of the railway wheel can be improved.

FIG. 1 is a vertical cross-sectional view of a railway wheel according to an embodiment. FIG. 2 is a graph showing the maximum principal stress of the plate portion of each wheel analysis model. FIG. 3 is a schematic view showing the deformation of the wheel analysis model.

The present inventors have studied the shape of the railway wheel diligently, and have found that the brake thermal stress generated in the plate portion is reduced by bending the plate portion relatively large 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 provided on the rim portion in which the tread surface and the flange are arranged in the axial direction. The present inventors have completed the railway wheels according to the embodiment based on the knowledge.

The wheel according to the embodiment is a wheel (railway wheel) used for a railroad vehicle. The wheel includes a tubular boss portion, a rim portion, and an annular plate portion. The boss portion constitutes the inner peripheral portion of the wheel. The axle of the railroad vehicle is inserted into the boss portion. The rim portion constitutes the outer peripheral portion of the wheel. The rim portion includes a tread and a flange. The tread contacts the top surface of the rail on which the railroad vehicle travels. The flange is adjacent to the tread in the axial direction of the wheel and projects outward from the tread in the radial direction of the wheel. The plate portion connects the boss portion and the rim portion. The plate portion is curved in the axial direction opposite to the side where the flange is located. The axial distance from the boss width center line to the curved apex is greater than 40 mm. The boss width center line is a straight line extending in the radial direction through the central position of the boss portion in the axial direction in the vertical cross section of the wheel. The curved apex is an inflection point on the plate thickness center line passing through the plate thickness center of the plate portion in the vertical cross section of the wheel, and is an inflection point at the position where the plate thickness center line is the farthest in the axial direction from the flange. (First configuration).

In the railway wheel according to the first configuration, the plate portion connecting the rim portion and the boss portion is curved to the side opposite to the side where the flange of the rim portion is located (anti-flange side) in the axial direction of the wheel. The curved apex of the plate thickness center line of the plate portion is arranged at a distance of more than 40 mm in the axial direction from the boss width center line. That is, the plate portion of the railway wheel according to the first configuration is largely curved toward the anti-flange side as compared with, for example, the plate portion of the railway wheel of Patent Document 1. As a result, it is possible to alleviate the concentration of stress on the curved apex of the plate portion when the wheel is braked. Therefore, the thermal stress generated in the plate portion can be reduced, and the plastic deformation of the plate portion can be suppressed. Therefore, the durability of the wheel can be improved.

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

According to the second configuration, the axial distance between the curved apex of the plate thickness center line and the boss width center line is limited to 135 mm or less. As a result, the plate portion does not bend excessively toward the anti-flange side. Therefore, it is possible to prevent the weight of the wheel from increasing or the shape from becoming complicated, making it difficult to manufacture the wheel. Further, it is possible to secure the strength of the plate portion with respect to the load in the radial direction of the wheel.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each figure, the same or equivalent configurations are designated by the same reference numerals, and the same description is not repeated.

[Railway wheel configuration]
FIG. 1 is a vertical cross-sectional view of the wheel 100 according to the present embodiment. The vertical cross section means a cross section obtained by cutting the wheel 100 on a plane including the central axis X. Since the vertical cross section of the wheel 100 is symmetrical with respect to the central axis X, FIG. 1 shows only one side of the central axis X of the wheels 100. In the present 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.

With reference to FIG. 1, the wheel 100 is a wheel (railway wheel) used in a railroad vehicle. The wheel 100 includes a boss portion 10, a rim portion 20, and a plate portion 30.

The boss portion 10 has a substantially cylindrical shape centered on the central axis X, and constitutes an inner peripheral portion of the wheel 100. An axle (not shown) of a railway vehicle is inserted into the boss portion 10. In FIG. 1, the boss width center line L1 is indicated by a chain double-dashed line. The boss width center line L1 is a virtual straight line extending in the radial direction through the central position of the boss portion 10 in the axial direction in the vertical cross-sectional view of the wheel 100.

The rim portion 20 has a substantially tubular shape centered on the central axis X, and constitutes an outer peripheral portion of the wheel 100. The rim portion 20 is arranged outside the boss portion 10 in the radial direction. In FIG. 1, the rim width center line L2 is indicated by a chain double-dashed line. The rim width center line L2 is a virtual straight line extending in the radial direction through the central position in the axial direction of the rim portion 20 in the vertical cross-sectional view of the wheel 100.

The rim portion 20 includes a tread surface 21 and a flange 22. The tread 21 is provided on the outer peripheral surface of the wheel 100. That is, the tread 21 is an annular surface outward in the radial direction. The tread 21 contacts the top surface of the rail on which the railroad vehicle travels. The diameter of the tread 21 gradually increases toward the flange 22 side. The shape of the tread 21 is not particularly limited. The tread 21 may be, for example, a conical tread or an arc tread.

The flange 22 is adjacent to the tread 21 in the axial direction. The flange 22 is provided at one end in the axial direction of the rim portion 20. In the present embodiment, the side where the flange 22 is located in the axial direction is referred to as the flange side, and the opposite side thereof is referred to as the anti-flange side. In other words, the front surface side of the wheel 100 is the anti-flange side, and the back surface side of the wheel 100 is the flange side. The flange 22 projects outward from the tread 21 in the radial direction. The flange 22 is positioned inside the left and right rails when the railroad vehicle travels on the rails.

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

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 intermediate point 231 of the throat 23 may be located on the flange side with respect to the boss width center line L1 or may be located on the anti-flange side. In the example of this embodiment, the intermediate point 231 of the throat 23 is located on the anti-flange side with respect to the boss width center line L1. Therefore, the rim width center line L2 is also arranged on the anti-flange side with respect to the boss width center line L1.

The plate portion 30 has an annular shape and connects the boss portion 10 on the inner peripheral side and the rim portion 20 on the outer peripheral side. The plate thickness of the plate portion 30 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 front surface 31 on the anti-flange side and a back surface 32 on the flange side. The inner peripheral ends of the front surface 31 and the back surface 32 are connected to the outer peripheral surface 11 of the boss portion 10 via the connecting portions 41a and 42a which are substantially arcuate in vertical cross-sectional view, respectively. The outer peripheral ends of the front surface 31 and the back surface 32 are connected to the inner peripheral surface 24 of the rim portion 20 via the connecting portions 41b and 42b which are substantially arcuate in vertical cross-sectional view, respectively.

The plate portion 30 is curved toward the anti-flange side. Therefore, the plate thickness center line A of the plate portion 30 is also curved toward the anti-flange side. The plate thickness center line A is a virtual curve passing through the plate thickness center of the plate portion 30. That is, the plate thickness center line A passes 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 being curved along the front surface 31 and the back surface 32.

The curved plate thickness center line A has a plurality of inflection points. Of the inflection points on the plate thickness center line A, the point at which the plate thickness center line A is farthest from the flange 22 in the axial direction is defined as the curved apex C. The curved apex C is arranged on the anti-flange side with respect to the boss width center line L1. However, it is preferable that the curved apex C does not protrude from the rim portion 20 toward the anti-flange side. That is, the curved apex C is preferably arranged on the flange side with respect to the front surface 25 of the rim portion 20. The axial distance d1 from the boss width center line L1 to the curved apex C is larger than 40 mm. The distance d1 is preferably 135 mm or less.

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

The angle θ formed by the plate thickness center line A with respect to the boss width center line L1 can be set, for example, in the range of 15 ° to 75 °, preferably in the range of 38 ° to 75 °. The angle θ is an angle between the straight line L3 obtained by linearly approximating the portion of the plate thickness center line A on the boss portion 10 side of the curved apex C and the boss width center line L1.

[effect]
In the wheel 100 according to the present embodiment, the curved apex C of the plate thickness center line A of the plate portion 30 is arranged 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 greatly curved toward the anti-flange side. As a result, when the wheel 100 is braked by the tread brake, the stress concentration of the plate portion 30 on the curved apex C can be relaxed. Therefore, the thermal stress generated in the plate portion 30 can be reduced, and the plastic deformation of the plate portion 30 can be suppressed. Therefore, the durability of the wheel 100 can be improved.

In the wheel 100 according to the present embodiment, the axial distance d1 from the boss width center line L1 to the curved apex C of the plate thickness center line A of the plate portion 30 is preferably set to 135 mm or less. By doing so, excessive bending of the plate portion 30 toward the anti-flange side is prevented. Therefore, the increase in the weight of the wheel 100 can be suppressed, and the wheel 100 can be easily manufactured without complicating the shape of the wheel 100. Further, by not bending the plate portion 30 excessively, it is possible to secure the strength of the plate portion 30 with respect to the load in the radial direction.

In the present embodiment, the radial distance d2 from the inner peripheral surface 24 of the rim portion 20 to the curved apex C of the plate thickness center line A of the plate portion 30 is preferably 124 mm or less. As a result, the thermal stress generated in the plate portion 30 can be reduced more reliably.

The distance d2 is preferably 63 mm or more. By doing so, it is possible to prevent the radius of curvature of the connecting portion 41b on the anti-flange side between the rim portion 20 and the plate portion 30 from becoming too small. Therefore, the occurrence of stress concentration in the connecting portion 41b can be suppressed, and the mechanical stress of the connecting portion 41b can be reduced.

In the present embodiment, the angle θ of the plate thickness center line A with respect to the boss width center line L1 is, for example, 15 ° to 75 °. By ensuring a sufficient angle θ, the connecting portion 42a on the flange side between the boss portion 10 and the plate portion 30 becomes a gentle arc shape. Therefore, stress concentration at the connecting portion 42a is less likely to occur, and the mechanical stress of the connecting portion 42a can be reduced.

Although the embodiment according to the present disclosure has been described above, the present disclosure is not limited to the above embodiment, and various changes can be made as long as the purpose is not deviated.

Hereinafter, the present disclosure will be described in more detail by way of examples. However, the present disclosure is not limited to the following examples.

Numerical analysis (FEM analysis) by the finite element method was carried out in order to evaluate the effect of the railway wheels according to the present disclosure. In the analysis, an analysis model having the same shape as the wheel 100 shown in FIG. 1 is created, and the axial distance d1 from the boss width center line L1 to the curved apex C of the plate thickness center line A is changed to change the plate portion 30. The thermal stress and the axial displacement of the rim portion 20 were evaluated. For comparison, the same evaluation was performed on the wheel shape analysis model disclosed in Patent Document 1.

The analysis was performed using general-purpose software (ABAQUS Ver.6.12, manufactured by Dassault Systèmes). In the analysis, in order to simulate the braking of a railroad vehicle by the tread brake, the heat flux required for decelerating the vehicle having an axle load of 40 tons on a downhill is applied to the area of the tread 21 that comes into contact with the brake shoes of the tread brake. Gave. The braking time was 1200 seconds, and the inner peripheral portion of the wheel 100 was completely restrained. Other analysis conditions and analysis results are shown in Table 1 and FIG.

[Thermal stress of the plate]
The thermal stress of the plate portion 30 was evaluated by the maximum principal stress of the plate portion 30 after 1200 seconds when the heat flux was applied to the wheel 100. The maximum principal stress of the plate portion 30 shown in Table 1 is the ratio of the wheel shape (No. 1) of Patent Document 1 to the maximum principal stress. As can be seen from Table 1, in the wheel shape (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 larger than 40 mm, the distance d1 is 35 mm. Compared with the wheel shape (No. 1) of Patent Document 1, the maximum principal stress of the plate portion 30 was significantly reduced. As shown in FIG. 2, when the distance d1 is 87 mm (No. 2), the maximum principal stress of the plate portion 30 is reduced by about 20% as compared with the wheel (No. 1) of Patent Document 1, and the distance d1 is reduced. In the case of 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 is 40 mm, the maximum principal stress of the plate portion 30 is about the same as the wheel shape (No. 1) in Patent Document 1.

[Displacement of rim part]
FIG. 3 is a schematic view showing the deformation of the wheel caused by braking as the amount of deformation: about 20 times. In FIG. 3, the outer shape of the wheel 100 before deformation is shown by a chain double-dashed line, and the outer shape of the wheel 100 after deformation is shown by a solid line. In the analysis, the position P of the wear limit (use limit) on the flange side surface of the rim portion 20 is compared between before the heat flux is applied to the wheel 100 and after 1200 seconds when the heat flux is applied to the rim portion 20. Axial displacement was evaluated.

In Table 1, when the displacement amount of the rim portion is positive, it means that the rim portion 20 is displaced to the anti-flange side, and when the displacement amount of the rim portion is negative, it means that the rim portion is displaced to the flange side. As can be seen from Table 1, the axial displacement of the rim portion was within the range (-1.0 mm to 3.0 mm) allowed by the European standard EN13979-1 for all wheels 100.

As described above, it was confirmed that the thermal stress generated in the plate portion 30 can be reduced by increasing the axial distance d1 from the boss width center line L1 to the curved apex C of the plate thickness center line A to be larger than 40 mm. .. It was also found that when the distance d1 is more than 40 mm, the axial displacement of the rim portion can be suppressed.

100: Wheel 10: Boss part 20: Rim part 21: Tread 22: Flange 30: Plate part L1: Boss width center line A: Plate thickness center line C: Curved apex

Claims (2)

Wheels used in railroad vehicles
A tubular boss portion that constitutes the inner peripheral portion of the wheel and into which the axle of the railway vehicle is inserted,
A tread that constitutes the outer peripheral portion of the wheel and is in contact with the crown surface of the rail on which the railroad vehicle travels, and is adjacent to the tread in the axial direction of the wheel and protrudes outward from the tread in the radial direction of the wheel. Flange, including rim,
An annular plate portion that connects the boss portion and the rim portion and curves in the axial direction on the side opposite to the side where the flange is located, and
With
In the vertical cross section of the wheel, a straight line that passes through the center position of the boss portion in the axial direction and extends in the radial direction is defined as the boss width center line, and a turning point on the plate thickness center line that passes through the plate thickness center of the plate portion. When the bending point at the position where the plate thickness center line is farthest from the flange in the axial direction is a curved apex, the axial distance from the boss width center line to the curved apex is Wheels larger than 40 mm. The wheel according to claim 1.
A wheel whose axial distance from the boss width center line to the curved apex is 135 mm or less.

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