Railway vehicle wheel

Abstract

A wheel (100) includes a hub portion (10), a rim portion (20), and a plate portion (30). The rim portion (20) includes a tread (21) and a rim flange (22). A center (Cr) of the rim portion (20) in an axial direction of the wheel (100) is configured to be closer to the rim flange (22) than a center (Cb) of the hub portion (10) in the axial direction. The plate portion (30) has a straight plate thickness center line (A) in a longitudinal sectional view of the wheel (100). An angle formed by the plate thickness center line (A) and the axial direction is denoted as α, a distance in the axial direction from a side surface (24) of the rim portion (20) to an outer end (Aa) of the plate thickness center line (A) is denoted as Pw, a length of the rim portion (20) in the axial direction is denoted as Wr, and Pw / Wr is denoted as L, the wheel (100) satisfies L ≥ 0.0223α-1.363. The angle α is 90° or less.

Description

Technical Field

[0001] This disclosure relates to a wheel used in railway vehicles. Background Technology

[0002] Tread braking is a known braking method for railway vehicles. Tread braking is a braking method that uses brake shoes pressed against the tread of the railway vehicle wheels to generate friction between the tread and the brake shoes, thus braking the railway vehicle.

[0003] When braking railway vehicles using tread brakes, frictional heat is generated between the tread and the brake shoes, causing the temperature of the wheel, especially the rim that forms the outer periphery of the wheel, to rise. This results in thermal expansion of the rim and the generation of thermal stress there. To reduce this thermal stress, various wheel shapes have been proposed in the past.

[0004] For example, Patent Document 1 discloses a wheel comprising a rim portion constituting the outer periphery of the wheel, a hub portion constituting the inner periphery of the wheel, and a plate portion having a generally S-shaped cross-section. In the wheel of Patent Document 1, to reduce the thermal stress of the plate portion and the rim portion, the displacement of the rim portion relative to the hub portion and the displacement of the plate portion on the rim portion side are each set to a predetermined value or higher. The displacement of the rim portion relative to the hub portion is the distance between a perpendicular line from the end of the curved plate thickness centerline on the rim portion side to the wheel axle, and a perpendicular line from the end of the plate thickness centerline on the hub portion side to the wheel axle. The displacement of the plate portion on the rim portion side is the distance between a perpendicular line from the end of the plate thickness centerline on the rim portion side to the wheel axle, and a perpendicular line from the center of the rim portion on the axial direction of the wheel to the wheel axle.

[0005] For example, Patent Document 2 proposes a wheel with a curved cross-sectional shape in the plate portion for the purpose of reducing thermal stress in the rim portion. In the wheel of Patent Document 2, the plate portion has a cross-sectional shape referred to as "bell-shaped". The two ends of the curved plate thickness centerline of this plate portion are arranged on the same side relative to the central plane of the wheel (a plane perpendicular to the wheel's axis). On the other hand, the midpoint of the plate thickness centerline is arranged on the opposite side relative to the central plane of the wheel, opposite to the two ends of the plate thickness centerline.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: Japanese Patent Application Publication No. 10-119503

[0009] Patent Document 2: Japanese Patent Publication No. 2009-545484 Summary of the Invention

[0010] The technical problem that the invention aims to solve

[0011] However, due to heat treatment and other processes during manufacturing, compressive residual stress is typically imparted to the rim of railway vehicle wheels. However, when a railway vehicle is braked by tread braking, if high thermal stress is generated in the rim causing plastic deformation, the compressive residual stress in the rim can sometimes transform into tensile residual stress. That is, during braking, friction between the tread and brake shoes causes the rim temperature to rise, leading to thermal expansion. On the other hand, because the temperature rise is smaller on the inner circumference of the wheel, thermal expansion of the rim is hindered, resulting in compressive stress in the rim, particularly in the circumferential direction. If this compressive stress exceeds the yield point, plastic deformation of the rim occurs. After the rim cools, the compressive stress transforms into tensile stress, acting as residual stress in the rim. Under conditions of tensile residual stress in the rim, if cracks form on the tread, it is considered that these cracks may propagate into the interior of the wheel. Therefore, when using tread braking in the braking of railway vehicles, it is necessary to reduce the thermal stress generated in the rim due to tread braking and to suppress the generation of tensile residual stress in the rim.

[0012] Both the wheels in Patent Documents 1 and 2 have a curved plate portion. This mitigates the restriction of thermal expansion of the rim portion by the plate portion. Therefore, it is believed that in the wheels of Patent Documents 1 and 2, the thermal stress generated in the rim portion during railway vehicle braking is reduced, and tensile residual stress becomes less likely to be generated in the rim portion. However, bending the plate portion also presents the problem of increased wheel weight.

[0013] The objective of this disclosure is to provide a wheel that can balance lightweight design with suppression of tensile residual stress in the rim.

[0014] Technical means for solving technical problems

[0015] The wheel disclosed herein is used in railway vehicles. The wheel includes a hub, a rim, and a plate. The hub forms the inner circumference of the wheel. An axle of the railway vehicle is inserted into the hub. The rim forms the outer circumference of the wheel. The rim includes a tread and a flange. The tread contacts the overhead surface of the track on which the railway vehicle travels. The flange protrudes further outward in the radial direction of the wheel than the tread. An annular plate connects the hub and the rim. The center of the axially extending rim is configured to be closer to the flange axially than the center of the axially extending hub. The axial direction is the direction in which the central axis of the wheel extends. In a longitudinal sectional view of the wheel, the plate has a straight centerline of plate thickness. When the angle between the plate thickness centerline and the axial direction is denoted as α, the axial distance from the side opposite to the rim to the outer end of the plate thickness centerline in the radial direction of the two axial sides of the rim is denoted as Pw, the axial length of the rim is denoted as Wr, and Pw / Wr is denoted as L, the wheel involved in this disclosure satisfies the following formula (1).

[0016] L≥0.0223α-1.363…(1)

[0017] Among them, the angle α is less than 90°. The angle α is defined as follows: when the center line of the plate thickness is parallel to the radial direction, it is 90°; when the center line of the plate thickness rotates from the 90° position to the opposite side of the flange with the inner end of the radial direction as the center, thus tilting relative to the radial direction, it is less than 90°.

[0018] Invention Effects

[0019] According to this disclosure, it is possible to balance wheel lightweighting with the suppression of residual tensile stress in the rim. Attached Figure Description

[0020] Figure 1 This is a longitudinal sectional view of the wheel in the embodiment.

[0021] Figure 2 This is a schematic diagram of a wheel with a plate having an S-shaped cross-section.

[0022] Figure 3 The diagram illustrates the relationship between the plate angle and the residual stress of the rim, for embodiments and comparative examples where the ratio of the plate position to the rim width is equal.

[0023] Figure 4 This is a graph showing the relationship between the ratio of the plate position to the rim width and the residual stress of the rim, for embodiments and comparative examples with equal plate angles.

[0024] Figure 5 The diagram is an exaggerated illustration of the deformation of the wheel during braking in the embodiment.

[0025] Figure 6 It is an exaggerated example in Figure 5 A diagram showing the deformation of the wheel during braking in other embodiments besides those shown.

[0026] Figure 7 The diagram is an exaggerated illustration of the deformation of the wheel during braking in the comparative example.

[0027] Figure 8 This is a diagram showing the boundary line where the residual stress in the rim does not translate into tension in the relationship between the plate angle and the ratio of the plate position to the rim width. Detailed Implementation

[0028] The wheel of embodiment (first configuration) is used in railway vehicles. The wheel includes a hub, a rim, and a plate. The hub forms the inner circumference of the wheel. The axle of the railway vehicle is inserted into the hub. The rim forms the outer circumference of the wheel. The rim includes a tread and a flange. The tread contacts the overhead surface of the track on which the railway vehicle travels. The flange protrudes further outward than the tread in the radial direction of the wheel. An annular plate connects the hub and the rim. The center of the rim in the axial direction is positioned closer to the flange in the axial direction than the center of the hub. Axial direction refers to the direction in which the central axis of the wheel extends. In a longitudinal sectional view of the wheel, the plate has a straight centerline of plate thickness. Let α be the angle between the plate thickness centerline and the axial direction, let Pw be the axial distance from the side opposite to the rim of the two axial sides of the rim to the outer end of the plate thickness centerline in the radial direction, let Wr be the axial length of the rim, and let L be Pw / Wr. The first wheel satisfies the following equation (1).

[0029] L≥0.0223α-1.363···(1)

[0030] Among them, the angle α is less than 90°. The angle α is defined as follows: when the center line of the plate thickness is parallel to the radial direction, it is 90°; when the center line of the plate thickness starts from the 90° position and rotates to the opposite side of the flange with the inner end of the radial direction as the center, thus tilting relative to the radial direction, it is less than 90°.

[0031] In the first configuration of the wheel, the center line of the plate thickness is straight in the longitudinal sectional view of the wheel, without any inflection points. That is, the plate connects the hub and rim portions substantially without bending. As a result, compared to a bent plate, the weight of the plate can be reduced. Thus, wheel lightweighting can be achieved.

[0032] When the brake shoes of the tread brake are pressed against the tread of the wheel rim and generate frictional heat, the rim expands thermally. Since the plate restricts this thermal expansion, thermal stress is generated in the rim. If the thermal stress in the rim becomes too high, plastic deformation occurs during braking of the railway vehicle, and residual tensile stress in the circumferential direction of the wheel may be generated after the rim cools. On the other hand, the first-configuration wheel is shaped to alleviate the constraint of the plate on the rim. More specifically, in the first-configuration wheel, the dimensions of each part are set with the premise that the center of the rim is located closer to the rim flange than the center of the hub, so as to satisfy Equation (1) which takes into account both the angle of the plate thickness centerline relative to the wheel axis and the position of the plate thickness centerline relative to the rim. Therefore, the constraint of the plate on the rim can be effectively alleviated, allowing for thermal expansion of the rim during braking. Thus, the thermal stress in the rim can be reduced, and plastic deformation of the rim can be suppressed. Therefore, it is possible to suppress the conversion of residual stress in the rim into tension when the rim is cooled after braking of a railway vehicle.

[0033] In this way, the wheel constructed according to the first configuration can achieve both lightweighting of the wheel and suppression of tensile residual stress in the rim.

[0034] As described above, in the first-construction wheel, the centerline of the plate thickness is a straight line in the longitudinal sectional view of the wheel, without any inflection points. In this case, stress concentration in the plate is unlikely to occur. Therefore, it is possible to reduce the thermal stress in the plate generated during railway vehicle braking.

[0035] According to the first configuration, the angle between the centerline of the plate thickness and the wheel's axial direction is 90° or less. Therefore, the plate does not tilt towards the inside of the track as it moves outward in the radial direction. This ensures the rigidity of the plate relative to the load the wheel experiences from the track in its axial direction when traversing a curve—in other words, relative to the load (lateral pressure) the wheel experiences from the inside of the track. Consequently, the stress generated in the plate can be reduced.

[0036] An angle α between the plate thickness centerline and the axial direction of 87° or less is preferred (second configuration).

[0037] According to the second configuration, the angle between the centerline of the plate thickness and the wheel axis is 87° or less. In this case, the plate will tilt outward towards the outside of the track as it moves outward in the radial direction. Therefore, the rigidity of the plate relative to lateral pressure can be improved, and the stress generated in the plate can be further reduced. In addition, since the necessity to increase the plate thickness to ensure the rigidity of the plate relative to lateral pressure is reduced, the plate and wheel can be made lighter.

[0038] The plate portion may also have a plate thickness that decreases as it moves outward in the radial direction and reaches its minimum near the outer end of the plate thickness centerline (third configuration).

[0039] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The same or equivalent structures in each drawing are labeled with the same reference numerals and will not be described repeatedly.

[0040] Figure 1 This is a longitudinal sectional view of the wheel 100 according to this embodiment. A longitudinal section refers to a cross-section of the wheel 100 cut off in a plane containing the central axis X. Because the longitudinal section of the wheel 100 is symmetrical about the central axis X, therefore... Figure 1 The image only shows one side of the central axis X of the wheel 100. Hereinafter, the direction of extension of the central axis X of the wheel 100 will be referred to as the axial direction, and the radial direction and circumferential direction of the wheel 100 will be referred to as the radial direction and circumferential direction, respectively.

[0041] Reference Figure 1 The wheel 100 is used in railway vehicles. The wheel 100 includes a hub 10, a rim 20, and a plate 30.

[0042] The hub portion 10 forms the inner circumference of the wheel 100. The hub portion 10 is generally cylindrical with the central axis X as its axis. The axle of the railway vehicle (not shown) is inserted into the hub portion 10.

[0043] The rim portion 20 forms the outer periphery of the wheel 100. The rim portion 20 is disposed on the outer side of the hub portion 10 in the radial direction. The rim portion 20 includes a tread 21 and a rim 22. The tread 21 and the rim 22 are provided on the outer periphery of the rim portion 20.

[0044] The tread surface 21 is an outward-facing surface in the radial direction. The tread surface 21 contacts the overhead surface of the track on which the railway vehicle travels. The diameter of the tread surface 21 typically increases significantly towards the wheel flange 22. The tread surface 21 can be, for example, a conical tread surface or a circular arc tread surface.

[0045] The rim 22 is disposed at one end of the axial direction of the rim portion 20. The rim 22 protrudes further outward than the tread 21 in the radial direction. When the railway vehicle travels on the track, the rim 22 is positioned inside the left and right tracks. Hereinafter, the side on which the rim 22 is disposed in the axial direction of the wheel 100 is referred to as the rim direction, and the opposite side is referred to as the anti-rim direction.

[0046] The rim portion 20 also includes two axially oriented sides 23 and 24. Side 23 is the side facing the rim 22, and side 24 is the side facing the opposite side of the rim 22. That is, side 23 is positioned in the rim direction relative to side 24. Side 24 is positioned in the anti-rim direction relative to side 23, separated from the tread 21 and the rim 22.

[0047] The rim portion 20 is positioned relative to the hub portion 10 in the flange direction. More specifically, the central Cr of the rim portion 20 in the axial direction is positioned closer to the flange 22 in the axial direction than the central Cb of the hub portion 10 in the axial direction. When the railway vehicle is in motion, the central Cr of the rim portion 20 is positioned inside the center of the hub portion 10 in the track width direction.

[0048] Plate portion 30 is annular. Plate portion 30 connects hub portion 10 and rim portion 20. The thickness of plate portion 30, overall, is smaller than both the hub width Wb and the rim width Wr. The thickness of plate portion 30 is greater on the hub portion 10 side and smaller on the rim portion 20 side. Hub width Wb is the axial length of hub portion 10. Rim width Wr is the axial length of rim portion 20, which is the maximum axial distance from side 23 to side 24 of rim portion 20.

[0049] The plate portion 30 includes two axially oriented side surfaces 31 and 32. Side surface 31 is the side surface on the rim 22 side, and side surface 32 is the side surface opposite to the rim 22. That is, side surface 31 is arranged in the rim direction relative to side surface 32. Side surface 32 is arranged in the anti-rim direction relative to side surface 31. In the longitudinal sectional view of the wheel 100, it is preferable that side surfaces 31 and 32 are inclined relative to the radial direction. Side surfaces 31 and 32 are connected to the rim portion 20 via connecting portions 41 and 42, respectively. Side surfaces 31 and 32 are connected to the hub portion 10 via connecting portions 43 and 44, respectively. Connecting portions 41, 42, 43, and 44 are substantially arc-shaped, for example, in the longitudinal sectional view of the wheel 100.

[0050] In this embodiment, the end located further in the radial direction of the end (arc starting point) 411 on the plate portion 30 side of the connecting portion 41 and the end (arc starting point) 421 on the plate portion 30 side of the connecting portion 42 is defined as the outer peripheral end of the plate portion 30. Similarly, the end located further in the radial direction of the end (arc starting point) 431 on the plate portion 30 side of the connecting portion 43 and the end point (arc starting point) 441 on the plate portion 30 side of the connecting portion 44 is defined as the inner peripheral end of the plate portion 30. The outer peripheral end of the plate portion 30 can also be referred to as the connection root of the plate portion 30 relative to the rim portion 20. The inner peripheral end of the plate portion 30 can also be referred to as the connection root of the plate portion 30 relative to the hub portion 10. In this embodiment, the end 411 of the connecting portion 41 and the end 441 of the connecting portion 44 are the outer peripheral end and the inner peripheral end of the plate portion 30, respectively.

[0051] The thickness of the plate portion 30 decreases towards the outer side in the radial direction, reaching its minimum near the outer peripheral end 411. The plate portion 30 has its minimum thickness near the outer peripheral end 411, which is radially inward. The position where the plate thickness of the plate portion 30 reaches its minimum substantially coincides with the position where the bending stress generated within the plate portion 30 due to the bending load on the wheel 100 from the track when the railway vehicle passes through a curve is minimal. For example, the plate thickness of the plate portion 30 can be set to its minimum at a position 5 mm to 30 mm radially inward from the outer peripheral end 411.

[0052] The plate portion 30 has a plate thickness centerline A. Plate thickness centerline A is a line extending from the hub portion 10 to the rim portion 20 in a longitudinal sectional view of the wheel 100, connecting the center of the plate thickness of the plate portion 30. Plate thickness centerline A passes through the middle of the sides 31 and 32, extending from the hub portion 10 side to the rim portion 20 side. Plate thickness centerline A appears as a straight line in the longitudinal sectional view of the wheel 100. Here, "straight line" does not only refer to a perfectly straight line, but also includes concepts such as very gentle arcs or broken lines with a radius of curvature of 1000 mm or more. That is, it is sufficient that plate thickness centerline A can be identified as a substantially straight line in the longitudinal sectional view of the wheel 100. Because plate thickness centerline A appears as a straight line in the longitudinal sectional view of the wheel 100, the plate portion 30 is generally flat and substantially does not bend axially.

[0053] The plate thickness centerline A has an outer end Aa in the radial direction and an inner end Ab in the radial direction. The outer end Aa is the point where a straight line passing through the outer peripheral end 411 of the plate portion 30 and extending axially connects to the plate thickness centerline A. The inner end Ab of the plate thickness centerline A is the point where a straight line passing through the inner peripheral end 441 of the plate portion 30 and extending axially connects to the plate thickness centerline A.

[0054] The position of the plate portion 30 relative to the rim portion 20 is determined based on the axial position of the outer end Aa of the plate thickness centerline A. In this embodiment, the axial distance from the side 24 in the opposite flange direction to the outer end Aa of the plate thickness centerline A is defined as the plate portion position Pw. The ratio of the plate portion position Pw to the rim width Wr is: L = Pw / Wr. The smaller the ratio, the farther the outer peripheral end 411 of the plate portion 30 is from the rim 22; the larger the ratio L, the closer the outer peripheral end 411 of the plate portion 30 is to the rim 22.

[0055] The ratio of the plate position Pw to the rim width Wr: L = Pw / Wr is determined by the relationship with the angle α of the plate thickness centerline A. It is stipulated that the ratio L of the plate position Pw to the rim width Wr and the angle α of the plate thickness centerline A satisfy the following formula (1).

[0056] L≥0.0223α-1.363···(1)

[0057] The angle α of the plate thickness centerline A is the angle between the plate thickness centerline A and the axial direction in the longitudinal sectional view of wheel 100. When the plate thickness centerline A is a very gentle curve, angle α is the angle between the tangent at the center of plate thickness centerline A (the midpoint between the outer end Aa and the inner end Ab) and the axial direction. When plate thickness centerline A is a broken line, angle α is the angle between the longest line segment constituting plate thickness centerline A and the axial direction. Regarding angle α, it is defined as 90° when plate thickness centerline A is parallel to the radial direction. Furthermore, when plate thickness centerline A is rotated from a position of 90° around the inner end Ab towards the opposite side of the rim 22, causing plate thickness centerline A to be inclined relative to the radial direction, angle α is defined as less than 90°. That is, with a position of 90° as a reference, if the outer end Aa of plate thickness centerline A is configured in the opposite rim direction, angle α is considered to be less than 90°.

[0058] The angle α of the plate thickness centerline A is set to 90° or less. Depending on the specifications of the tread brake used on the wheel 100, angle α is preferably 87° or less. The smaller the angle α, the more the plate portion 30 tilts towards the reverse flange direction, the more the restriction of the plate portion 30 on the rim portion 20 is mitigated, and the easier it is to tolerate deformation of the rim portion 20 during railway vehicle braking. From a manufacturing point of view of the wheel 100, an angle α of 75° or more is preferred.

[0059] On the other hand, the larger the ratio L of the plate portion position Pw to the rim width Wr, the closer the base of the plate portion 30 is to the rim flange 22 relative to the rim portion 20, the more relaxed the restriction of the plate portion 30 on the rim portion 20 is, and the easier it is to allow deformation of the rim portion 20 during railway vehicle braking. From the viewpoint of wheel 100 manufacturing, it is preferable to set the ratio L in the range of 0.3 or higher and 0.7 or lower.

[0060] [Effect]

[0061] In the wheel 100 of this embodiment, in order to alleviate the restriction of the plate portion 30 on the rim portion 20, the angle α of the plate thickness centerline A and the ratio L of the plate portion position Pw to the rim width Wr are appropriately set. Specifically, in this embodiment, assuming that the center Cr of the rim portion 20 is located closer to the rim 22 than the center Cb of the hub portion 10, and that the plate portion 30 and its plate thickness centerline A are straight in the longitudinal sectional view of the wheel 100, the angle α of the plate thickness centerline A and the ratio L of the plate portion position Pw to the rim width Wr are set to satisfy the relationship of Equation (1). As a result, in the wheel 100 in which the center Cr of the rim portion 20 is located closer to the rim 22 than the center Cb of the hub portion 10, and the plate portion 30 and its plate thickness centerline A are straight, the restriction of the plate portion 30 on the rim portion 20 can be effectively reduced. Therefore, when the brake shoes of the tread brake are pressed against the tread 21 of the rim portion 20 and frictional heat is generated, the thermal expansion of the rim portion 20 becomes difficult to prevent. Thus, when a tread brake is used in railway vehicle braking, the thermal stress on the rim portion 20 generated by the tread brake can be reduced, and plastic deformation of the rim portion 20 can be suppressed. As a result, after the rim portion 20 is cooled, the residual stress in the rim portion 20 can be prevented from converting into tension.

[0062] In the wheel 100 according to this embodiment, the center line A of the plate thickness of the plate portion 30 is a straight line in the longitudinal sectional view of the wheel 100 without any inflection points. That is, the plate portion 30 connects the hub portion 10 and the rim portion 20 substantially without bending. Therefore, compared with when the plate portion 30 is bent, the weight of the plate portion 30 can be reduced. Therefore, the wheel 100 can be made lighter.

[0063] Furthermore, since the plate thickness centerline A is straight and the plate portion 30 is substantially non-bent, stress concentration in the plate portion 30 can be mitigated during braking of railway vehicles using tread brakes. Therefore, the thermal stress in the plate portion 30 generated during railway vehicle braking can be reduced.

[0064] For example, when the plate portion 30 tilts towards the wheel flange (inner side of the track) as it moves outward in the radial direction, the rigidity of the plate portion 30 decreases relative to the load (lateral pressure) exerted on the wheel 100 in its axial direction by the track when passing through a curve, i.e., the load (lateral pressure) exerted on the wheel 100 by the track pressing it towards the wheel flange. In contrast, in this embodiment, since the angle α of the plate thickness centerline A is set to 90° or less, the plate portion 30 does not substantially tilt towards the wheel flange as it moves outward in the radial direction. Therefore, the rigidity of the plate portion 30 against lateral pressure can be ensured. Consequently, the stress generated in the plate portion 30 can be reduced.

[0065] In the wheel 100 of this embodiment, the angle α of the plate thickness centerline A is preferably 87° or less. In this case, the plate portion 30 tilts towards the opposite wheel flange direction (outside the track) as it moves outward in the radial direction. This improves the rigidity of the plate portion 30 relative to lateral pressure and further reduces the stress generated in the plate portion 30.

[0066] In the longitudinal sectional view of the wheel 100, when the sides 31 and 32 of the plate portion 30 are parallel to the radial direction of the wheel 100 (perpendicular to the central axis X of the wheel 100), the rim portion 20 is more easily restricted by the plate portion 30. Therefore, it is preferable that the sides 31 and 32 of the plate portion 30 are inclined relative to the radial direction of the wheel 100. The sides 31 and 32 may also be inclined relative to the radial direction, for example, in a manner that they move toward the opposite rim direction (outer side of the track) as they approach the rim portion 20. By inclining the sides 31 and 32 relative to the radial direction, the restriction of the plate portion 30 on the rim portion 20 can be further alleviated.

[0067] In this embodiment, the thickness of the plate portion 30 decreases towards the outer side in the radial direction, reaching its minimum near the outer end Aa of the plate thickness centerline A. More specifically, the position in the plate portion 30 where the bending stress caused by the bending load from the track when passing through a curve is minimized is substantially the same as the position where the plate thickness is minimized. In this way, fatigue failure of the plate portion 30 can be prevented, and the durability of the wheel 100 can be improved.

[0068] The above is a description of the embodiments involved in this disclosure, but this disclosure is not limited to the described embodiments, and various changes can be made as long as they do not depart from its spirit.

[0069]

Example

[0070] The present disclosure will now be described in more detail with reference to embodiments. However, the present disclosure is not limited to the following embodiments.

[0071] To investigate a wheel shape capable of suppressing tensile residual stress in the rim, a numerical analysis based on the finite element method (FEM analysis) was performed. In the FEM analysis, a wheel 100 (as described in the embodiment) was fabricated. Figure 1 For analytical models with the same shape, the residual stress in the rim was evaluated by varying the angle α (plate angle) of the straight plate thickness centerline A and the ratio L = Pw / Wr of the plate position relative to the rim width Wr. Additionally, the residual stress in the rim was also evaluated for analytical models of wheels with S-shaped plate sections. Figure 2 This is a schematic diagram of a wheel with an S-shaped cross-section. The conditions for parameters α and L are shown in Table 1.

[0072] Table 1

[0073] The FEM analysis was performed using general-purpose software (ABAQUS Ver. 6.12, manufactured by Dassault Systèmes). In the analysis, to simulate the braking of a railway vehicle by a tread brake, a heat flux was supplied to the area of ​​the wheel tread that contacts the brake shoes of the tread brake. The braking time was set to 1200 seconds, and the inner circumference of the wheel was set to full restraint.

[0074] The residual stress of the wheel rim obtained by FEM analysis is shown in Table 2. In Table 2, the residual stress of the wheel rim represents the maximum circumferential stress of the wheel rim after braking and cooling. If the residual stress of the wheel rim is negative, the residual stress of the wheel rim is still in compression after braking; if the residual stress of the wheel rim is positive, it indicates that the residual stress of the wheel rim is converted into tension after braking.

[0075] Table 2

[0076] As shown in Table 2, in Examples 1-3, the residual stress in the rim was negative. That is, in Examples 1-3, since the thermal stress in the rim was reduced during braking, the residual stress in the rim remained in a compressed state after braking. On the other hand, in Comparative Examples 1-3, the residual stress in the rim became positive. That is, in Comparative Examples 1-3, the residual stress in the rim was converted into tension after braking. In Comparative Example 4, although the residual stress in the rim was negative, the weight of the wheel increased compared to Examples 1-3 and Comparative Examples 1-3 where the plate was not bent, because the plate was bent. Therefore, in Examples 1-3, the weight of the wheel was not increased, and the generation of tensile residual stress in the rim was suppressed.

[0077] The following study will investigate the effects of plate angle α and the ratio L of plate position Pw to rim width Wr on the residual stress in the rim.

[0078] Figure 3 These are examples 1, 1, and 2, where the ratio L of the plate position Pw to the rim width Wr is equal, showing a graph illustrating the relationship between the plate angle α and the residual stress of the rim. Figure 3 As shown, the larger the plate angle α, the greater the residual stress in the wheel rim. Therefore, it can be said that when the plate angle α decreases, the possibility of the residual stress in the wheel rim being converted into tension after the railway vehicle brakes decreases.

[0079] Figure 4These are graphs illustrating the relationship between the ratio L of the plate position Pw to the rim width Wr and the residual stress of the rim, for Examples 3, 2, and 3 where the plate angle α is equal. Figure 4 As shown, the larger the ratio L of the plate position Pw to the rim width Wr, the smaller the value of the residual stress in the rim. Therefore, it can be said that when the ratio L increases, the possibility of the residual stress in the rim being converted into tension after the railway vehicle brakes decreases.

[0080] Thus, the smaller the plate angle α, the lower the residual stress in the rim section; and the larger the ratio L of the plate position Pw to the rim width Wr, the lower the residual stress in the rim section. The reasoning is as follows: Figures 5-7 Please provide an explanation. Figures 5-7 These are diagrams that exaggerate the deformation that occurs on the wheel during braking, as shown in Example 1, Example 2, and Comparative Example 2, respectively.

[0081] In Example 1, where the plate angle α is as small as 80°, such as Figure 5 As shown, when a heat flow is supplied to the tread surface 21, the rim portion 20 moves significantly in the rim direction. That is, in Embodiment 1, because the plate angle α is small, the restriction of the plate portion 30 on the movement of the rim portion 20 in the rim direction is reduced, allowing for thermal expansion of the rim portion 20. Therefore, in Embodiment 1, the thermal stress generated in the rim portion 20 during braking is reduced, and the residual stress in the rim portion 20 remains in a compressed state after braking.

[0082] In embodiment 2, where the ratio L of the plate position Pw to the rim width Wr is relatively large at 0.580, such as Figure 6 As shown, when a heat flow is supplied to the tread surface 21, the rim portion 20 rotates in the rim direction. That is, in Embodiment 2, since the ratio L is ensured, the restriction of the plate portion 30 on the rotation of the rim portion 20 in the rim direction is reduced, allowing for thermal expansion of the rim portion 20. Therefore, in Embodiment 2, the thermal stress generated in the rim portion 20 during braking is reduced, and the residual stress in the rim portion 20 remains in a compressed state after braking.

[0083] In contrast, in Comparative Example 2, the plate angle α is greater than 90° in Example 1, and the ratio L of the plate position Pw to the rim width Wr is less than 0.448 in Example 2. Figure 7 As shown, the rim portion 20 hardly moved or rotated. In Comparative Example 2, the plate portion 30 significantly restricted the movement and rotation of the rim portion 20, hindering the thermal expansion of the rim portion 20 when providing a heat flow to the tread surface 21. Therefore, in Comparative Example 2, the thermal stress generated in the rim portion 20 during braking increased, and the residual stress in the rim portion 20 was converted into tension after braking.

[0084] Thus, the plate angle α and the ratio L of the plate position Pw to the rim width Wr are related to the tensile transformation of the residual stress in the rim caused by the tread brake. Therefore, the relationship between the plate angle α and the ratio L that prevents the residual stress in the rim from transforming into tension when braking railway vehicles with a tread brake is determined. The boundary line where the residual stress in the rim will not transform into tension in the relationship between the plate angle α and the ratio L is as follows: Figure 8 As shown.

[0085] Figure 8 The plotted points are obtained by performing the same FEM analysis as above, representing the ratio L = plate position Pw / rim width Wr when the plate angle α = 78°, 80°, 85°, 87°, 90° and the residual stress of the rim is 0. Figure 8 The straight line in the figure is obtained by least-squares approximation of these plotted points, and is expressed as L=0.0223α-1.363. In the region above this straight line, the residual stress of the rim is compressive. Therefore, the case that can substantially prevent the residual stress of the rim from becoming tensile refers to the case where the plate angle α and the ratio L satisfy the following equation (1). Wherein, the plate angle α is set to 90° or less. The following equation (1) applies only to wheels where the center of the rim is positioned closer to the rim flange than the center of the hub, and the center lines of the plate and its thickness are straight.

[0086] L≥0.0223α-1.363···(1)

[0087] For each embodiment and comparative example, it was confirmed whether the stated equation (1) was satisfied. As shown in Table 3, embodiments 1 to 3 with negative residual stress in the rim satisfied the stated equation (1). On the other hand, comparative examples 1 and 2 with positive residual stress in the rim did not satisfy the stated equation (1). Therefore, in a wheel in which the center of the rim portion is positioned closer to the rim flange than the center of the hub portion, and the center lines of the plate portion and its thickness are straight, when the ratio L of the plate angle α to the plate portion position Pw relative to the rim width Wr is set to satisfy the stated equation (1), it can be said that the generation of tensile residual stress in the rim portion can be suppressed.

[0088] Table 3

[0089]

[0090] Explanation of reference numerals in the attached figures

[0091] 100: Wheel

[0092] 10: Wheel hub

[0093] 20: Wheel rim section

[0094] 21: Treading

[0095] 22: Wheel rim

[0096] 30: Plate section

[0097] A: Plate thickness centerline

Claims

1. A wheel for use in railway vehicles, comprising: The hub portion, which forms the inner circumference of the wheel, is into which the axle of the railway vehicle is inserted; The rim portion, which constitutes the outer periphery of the wheel, includes a tread that contacts the overhead surface of the track on which the railway vehicle travels, and a flange that protrudes outward in the radial direction of the wheel than the tread. as well as, An annular plate portion that connects the hub portion and the rim portion. The center of the rim portion extending axially from the central axis of the wheel is configured to be closer to the rim flange in the axial direction than the center of the hub portion in the axial direction. The plate portion has a straight centerline of plate thickness in the longitudinal sectional view of the wheel. Let α be the angle between the plate thickness centerline and the axial direction. This angle is defined as follows: 90° when the plate thickness centerline is parallel to the radial direction; and less than 90° when the plate thickness centerline rotates from the 90° position towards the opposite side of the rim with the inner end of the radial direction as its center, thus tilting relative to the radial direction. The distance in the axial direction from the side opposite to the rim of the rim portion to the outer end in the radial direction of the plate thickness center line is denoted as Pw, and the length of the rim portion in the axial direction is denoted as Wr. When Pw / Wr is denoted as L, the following equation (1) is satisfied. L≥0.0223α-1.363…（1） Wherein, the angle α is less than 90°.

2. The wheel as claimed in claim 1, wherein, The angle α is below 87°.

3. The wheel as described in claim 1 or 2, wherein, The plate portion has a plate thickness that decreases as it moves outward in the radial direction and reaches its minimum near the outer end of the plate thickness centerline.

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