JP7745673B2 - Railroad vehicle frame structure, railroad vehicle, and backing plate - Google Patents

Description

The present invention relates to a railway vehicle underframe structure that has chamfered corners where the side sills and end sills are joined, a railway vehicle, and a backing metal.

For example, on a double-track railway, if a derailed train runs onto the oncoming track, an offset collision may occur, in which the corners of the derailed train collide with a train traveling on the oncoming track, potentially causing damage.

For example, the railway vehicle described in Patent Document 1 has diagonally chamfered corner posts connecting the side and end structures and the corners of the underframe to which the corner posts are connected, which allows the vehicle to deflect oncoming vehicles in the event of an offset collision, mitigating the impact load and minimizing vehicle damage (see Patent Document 1).

Japanese Patent Application Laid-Open No. 2020-100198

The underframe described in Patent Document 1, for example, requires that both ends of the end beam in the vehicle width direction be cut obliquely at a predetermined angle to provide chamfered portions, which results in poor underframe productivity.

One possible underframe structure is to manufacture corner members with chamfered portions separately from the side sills and end sills, and then butt-weld them to the side sills and end sills to assemble the corners of the underframe. To ensure flatness at the welds between the corner members and side sills, and between the corner members and end sills, backing metal made of rectangular flat material is welded to the back of each weld.

Backing strips are partially welded to the end beams and side beams to suppress welding distortion and maintain flatness. The welding position is determined in advance, taking into account factors such as lifting of the backing strip due to welding. Before welding, the backing strips require marking to clearly indicate the welding position. As a result, with conventional underframe structures, assembling the corners of the underframe is time-consuming, which can reduce underframe productivity.

One aspect of the technology developed to solve the above-mentioned problems is (1) a railway vehicle underframe structure having chamfered portions at corners connecting side beams and end beams, comprising corner members each having the chamfered portion and butt-welded to the side beams and end beams to form the corners, and backing metals that are placed and partially welded to the backsides of the welded portions between the corner member and the side beams and the backsides of the welded portions between the corner member and the end beams, and the backing metals are formed from flat plates and have recesses at each partial weld position.

In the railway vehicle underframe structure having the above configuration, the partial welding positions of the backing metal are clearly indicated by recesses formed in the backing metal, eliminating the need for marking work to indicate the partial welding positions before welding the backing metal. Therefore, the railway vehicle underframe structure having the above configuration simplifies the assembly work of corner sections and improves underframe productivity.

(2) In the railway vehicle underframe structure described in (1), it is preferable that the backing metal is welded to a portion of the inner edge of the recess that is away from the opening.

In a railway vehicle underframe structure having the above configuration, the inner edge of the recess is welded away from the opening, so weld beads that occur when the backing metal is partially welded are less likely to form outside the recess. Therefore, with a railway vehicle underframe structure having the above configuration, weld beads that can interfere with subsequent processes are less likely to occur when the backing metal is welded, reducing the effort required to remove weld beads.

(3) In the railway vehicle underframe structure described in (1) or (2), it is preferable that the recess is formed in a rectangular shape and the backing metal is welded to the bottom of the recess.

In the railway vehicle underframe structure having the above configuration, the backing metal is line-welded along the bottom of the rectangular recess, making it easy to manage the weld length to suppress distortion caused by welding. Since the weld bead that forms when the backing metal is partially welded is less likely to form outside the recess, the effort required to remove the weld bead, which can interfere with subsequent processes, is reduced.

(4) In the railway vehicle underframe structure described in any one of (1) to (3), it is preferable to have a jack support plate fixed to the underside of the corner portion, and an L-shaped reinforcing member arranged above the jack support plate and connected to the end beam and the side beam at a position outside the recess of the backing metal.

The railway vehicle underframe structure having the above configuration allows the reinforcing members to be attached while avoiding the welded portion of the backing metal, reducing the labor required to remove the weld beads that are generated when welding the backing metal.

Another aspect of the technology disclosed herein is (5) a railway vehicle comprising an underframe, side structures connected to both ends of the underframe in the vehicle width direction, end structures connected to both ends of the underframe in the vehicle length direction, and a roof structure connected to the upper ends of the side structures and the end structures, wherein the underframe has side beams, end beams, corner members each having a chamfered portion and butt-welded to the side beams and end beams to form corner portions of the underframe, and backing metals that are partially welded to the backsides of the welded portions between the corner members and the side beams and the backsides of the welded portions between the corner members and the end beams, and the backing metals are formed from flat plates and have recesses at each partial weld position.

Furthermore, another aspect of the technology disclosed in this specification is (6) a backing metal used in a railway vehicle underframe in which side beams and end beams are butt-welded to corner members, which is placed and partially welded on the back side of the welded portion between the side beams and the corner member and the back side of the welded portion between the corner member and the end beam, and is formed from a flat plate and has a recess at each partial weld position.

The railway vehicle and backing plate having the above configuration can also realize the functions of the above-mentioned underframe structure, and are novel and useful.

The technology disclosed in this specification realizes a technology for underframe structures that have corner sections that connect end beams and side beams, simplifying the assembly work of the corner sections and improving underframe productivity.

1 is a schematic perspective view of a body structure of a railway vehicle according to an embodiment of the present invention. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. FIG. 3 is an exploded perspective view of part B in FIG. 2 . 10A to 10C are diagrams illustrating the underframe assembly procedure. 10A to 10C are diagrams illustrating the underframe assembly procedure. 7 is an enlarged view of a backing metal welding portion shown in part D of FIG. 6. FIG. 10A to 10C are diagrams illustrating the underframe assembly procedure. FIG. 9 is a view of FIG. 8 as seen from the back side. 10A to 10C are diagrams illustrating the underframe assembly procedure. 10A to 10C are diagrams illustrating the underframe assembly procedure.

The following describes in detail the railway vehicle underframe structure, railway vehicle, and backing bar of this embodiment, with reference to the accompanying drawings. This specification discloses a railway vehicle that uses an underframe with corner portions that connect the end sills and side sills.

(General configuration of railway vehicles)
The schematic configuration of a railway vehicle 1 of this embodiment will be described with reference to Figures 1 to 4. X, Y, and Z shown in each drawing indicate the orientation of the railway vehicle 1. X indicates the vehicle length direction, Y indicates the vehicle width direction, and Z indicates the up-down direction. Front indicates the front side in the direction of vehicle travel, and rear indicates the rear side in the direction of vehicle travel. Left indicates the left side of the railway vehicle 1 when viewed from the rear of the vehicle, and right indicates the right side of the railway vehicle 1 when viewed from the rear of the vehicle. Up indicates the overhead side, and down indicates the ground side.

As shown in Figure 1, the railway vehicle 1 has a carbody 6 configured to form a hexahedron by an underframe 2, side structures 3, end structures 4, and a roof structure 5. The underframe 2 is rectangular, and has floor panels (not shown) attached to it. The underframe 2 has the lower ends of the side structures 3 connected to both left and right ends, and the lower ends of the end structures 4 connected to both front and rear ends. The end structure 4 has corner posts 7 erected at both left and right ends, and is connected to the front ends of the side structures 3 via these corner posts 7. The roof structure 5 is connected to the upper ends of the side structures 3 and end structures 4.

The carbody 6 has carbody chamfers CH provided at each of the four corners C along the vertical direction Z. The carbody chamfers CH are formed by inclined surfaces that slope at an acute angle relative to the end body structure 4 and the side body structure 3. The carbody chamfers CH are composed of chamfers 71 provided on the corner posts 7 and chamfers 233 provided on the underframe 2.

(General configuration of the underframe)
As shown in Fig. 2, the underframe 2 includes a pair of side sills 22L, 22R extending in the vehicle length direction X, and an end sill 21 extending in the vehicle width direction Y. The underframe 2 has corner portions C formed by connecting the left and right end portions of the end sill 21 to the front ends of the side sills 22L, 22R via corner members 23, respectively. Although not shown, the corner portion provided at the rear end of the underframe is also configured in the same way. Since each corner portion C of the underframe 2 is configured in the same way, the following description will be given taking the left front corner portion C shown in part B of Fig. 2 as an example.

As shown in Figures 2 and 3, at the corner portion C of the underframe 2, the end sill 21 and the side sill 22L are butt-welded to the corner member 23.

As shown in Figure 3, backing metals 41 are welded to the underframe 2 on the backside of welded portion P1 between the end sill 21 and corner member 23, and on the backside of welded portion P2 between the side sill 22L and corner member 23. A lower plate 32 is attached to the underframe 2 along the underside of the end sill 21, and a jack support plate 33 is attached to the underside of the corner portion C. An L-shaped reinforcing member 42 is placed in the corner portion C to increase the rigidity of the underframe 2 when it is lifted via the jack support plate 33.

In this embodiment, the end beam 21, side beams 22L and 22R, corner members 23, backing metal 41, reinforcing member 42, lower plate 32, and jack support plate 33 are made of metal such as stainless steel or carbon steel.

Referring to Figure 4, the components that make up the corner section C will be described in detail. The end beam 21 has a floor support section 212 and a lower plate mounting section 213 that are bent rearward along the upper and lower edges of the end surface section 211 that extends in the vehicle width direction Y. The lower plate mounting section 213 has a smaller width in the vehicle length direction X than the floor support section 212, as the backing metal 41 is welded to the lower plate mounting section 213.

The side beam 22L has a side surface portion 221 extending in the vehicle length direction X. The upper and lower ends of the side surface portion 221 are connected to an upper surface portion 222T and a lower surface portion 222B via bent portions 224T and 224B. The upper surface portion 222T and the lower surface portion 222B are arranged horizontally. The upper surface portion 222T has an upper mounting portion 223T extending forward from the side surface portion 221. The lower surface portion 222B, like the upper surface portion 222T, has a lower mounting portion 223B.

The corner member 23 includes a first joint 231, a second joint 232, and a chamfered portion 233. The first joint 231 extends in the vehicle width direction Y and is butt-welded to the end sill 21. The second joint 232 extends in the vehicle length direction X and is butt-welded to the side sill 22L. The first joint 231 and the second joint 232 are arranged perpendicular to each other. The chamfered portion 233 is located between the first joint 231 and the second joint 232 and is formed by an inclined surface that is inclined at an acute angle to the first joint 231 and the second joint 232. In this embodiment, the corner member 23 and the corner post 7 are formed by cutting an extrusion molded product and have the same shape except for their height in the vertical direction Z.

The upper mounting portion 223T and the lower mounting portion 223B are each formed in a right-angled pentagon (a shape in which each portion of a rectangle is cut diagonally) so as to support the corner member 23 from the back side. For example, the upper mounting portion 223T extends from the left end of the upper surface portion 222T to an imaginary plane formed by extending the side surface portion 221 forward. The upper mounting portion 223T includes a first abutment portion 223a, a second abutment portion 223b, and a third abutment portion 223c. The first abutment portion 223a is butt-welded to the first joint portion 231 of the corner member 23. The second abutment portion 223b is butt-welded to the second joint portion 232 of the corner member 23. The third abutment portion 223c is butt-welded to the chamfered portion 233 of the corner member 23. The second abutment portion 223b is located on an imaginary plane extending forward from the side surface portion 221. The lower mounting portion 223B is configured in the same manner as the upper mounting portion 223T.

The backing metal 41 is made of a rectangular flat plate and is partially welded to the inner surface 211a of the end face portion 211 that constitutes the end beam 21 and the inner surface 221a of the side surface portion 221 that constitutes the side beam 22L. The partial welding positions of the backing metal 41 are determined in advance to suppress welding distortion, and a recess 411 is provided at each partial welding position. In this embodiment, the backing metal 41 has two rectangular recesses 411 cut out of the long side end portion 412, which is one of the four ends. The backing metal 41 is formed, for example, by cutting it out from plate material using laser processing.

The lower plate 32 has a rectangular shape. The lower plate 32 is disposed from the lower surface 222B of the side beam 22L to the lower surface 222B of the side beam 22R. The width of the lower plate 32 in the vehicle length direction X is greater than the lower plate mounting portion 213 of the end beam 21, and the lower plate 32 is disposed parallel to the floor support portion 212 of the end beam 21. Furthermore, the lower plate 32 has a protruding portion 32a (approximately rectangular in this embodiment) that protrudes from the left end, and the protruding portion 32a is overlapped and joined to the underside of the lower mounting portion 223B of the side beam 22L.

The jack support plate 33 is rectangular. It is joined to the lower plate 32 and its protruding portion 32a by welding or other means. The reinforcing member 42 is a rectangular plate bent at a substantially right angle in the middle, giving it an L-shaped cross section. The reinforcing member 42 is positioned above the jack support plate 33 with the bent portion protruding on the side opposite the corner member 23. By being welded to the end beam 21, side beam 22L, and lower plate 32, the rigidity of the mounting portion of the jack support plate 33 can be increased.

(Frame assembly procedure)
The procedure for assembling the underframe 2 will now be described. As shown in Fig. 5, the end beam 21 is joined to the side beam 22L at its left end. That is, for example, as shown at W11 in Fig. 5, the left edge of the floor support portion 212 of the end beam 21 is butt-welded to the right edges of the upper surface portion 222T and upper mounting portion 223T that constitute the side beam 22L. As shown at W12 in Fig. 5, the left edge of the lower plate mounting portion 213 of the end beam 21 is butt-welded to the right edge of the lower mounting portion 223B that constitutes the side beam 22L.

As shown in Figure 6, backing metal 41 is welded to each of the end beam 21 and the side beam 22L. Specifically, the backing metal 41 is partially welded to the inner surface 211a at the left end of the end face portion 211 that constitutes the end beam 21, and to the inner surface 221a at the front end of the side face portion 221 that constitutes the side beam 22L.

For example, as shown in FIG. 7, the backing metal 41 has recesses 411 formed at each partial welding position. In this embodiment, the backing metal 41 has a length L1 of the long side end 412 of 100 mm, an opening width L2 of the recesses 411 of 30 mm, and a spacing L3 of 30 mm between the recesses 411. The backing metal 41 allows the partial welding positions to be confirmed using the recesses 411 as markers, without the need for marking work to clearly indicate the welding positions before welding.

As shown in W21 in Figure 7, the backing metal 41 protrudes leftward from the left end of the end surface portion 211, and the bottoms 411a of each recess 411 are line-welded to the inner surface 211a of the end surface portion 211, with the recesses 411 positioned on the inner surface 211a of the end surface portion 211. Because the weld length of the backing metal 41 is determined by the bottoms 411a of each recess 411, distortion due to welding heat is suppressed, and a flat state can be maintained even after welding.

A weld bead is formed at the welded portion of the backing metal 41. Because the bottom 411a of the recess 411 of the backing metal 41 is line-welded, the weld bead is contained within the recess 411 and does not extend beyond the long side edge 412. Therefore, the weld bead on the backing metal 41 does not interfere with subsequent processes such as welding the reinforcing member 42, and there is no need to remove the weld bead.

As shown by W31 and W32 in Figure 8, the corner member 23 is butt-welded to the end beam 21 and the side beam 22L. For example, as shown by W31 in Figure 8, when welding portion P1 between the end beam 21 and the corner member 23 from the front side, the backing metal 41 arranged on the back side of the welding portion P1 melts between the end beam 21 and the corner member 23 due to the welding heat, firmly joining the end beam 21 and the corner member 23. The same applies to the backing metal 41 arranged on the back side of the welding portion P2 between the side beam 22L and the corner member 23.

The backing metal 41 ensures flatness during partial welding. By abutting against the backing metal 41, the corner member 23 is positioned flush with the end face 211 of the end sill 21 and the side face 221 of the side sill 22L. Therefore, the underframe 2 can be butt-welded to the end sill 21 and side sill 22L with the corner member 23 positioned flush with the end sill 21 and side sill 22L, forming a good-looking corner portion C.

As shown in Figure 9, the corner member 23 welded to the end beam 21 and side beam 22L has the inner surfaces 231a, 232a, 233a of the first joint portion 231, second joint portion 232, and chamfered portion 233 abutting against the first abutment portion 223a, second abutment portion 223b, and third abutment portion 223c (see Figure 6) of the upper mounting portion 223T and lower mounting portion 223B that make up the side beam 22L. The corner member 23 is supported and reinforced from the back side by the upper mounting portion 223T and lower mounting portion 223B.

As shown in Figure 10, the lower plate 32 is disposed in the vehicle width direction Y along the end sill 21 and is welded to the lower plate mounting portion 213 of the end sill 21 and to the lower surface portion 222B and lower mounting portion 223B of the side sill 22L. The jack support plate 33 is welded to the left front corner and protrusion 32a of the lower plate 32. The welding method may be, for example, fillet welding along the joint surface, or partial welding such as spot welding.

As shown in FIG. 11, the reinforcing member 42 is inserted between the floor support portion 212 and the lower plate mounting portion 213 with the bent portion protruding opposite the corner member 23, and abuts against the inner surface 211a of the end face portion 211 at a position to the right of the long side end portion 412 of the backing metal 41 welded to the end beam 21, and abuts against the inner surface 221a of the side face portion 221 at a position rearward of the long side end portion 412 of the backing metal 41 welded to the side beam 22L. As indicated by W41, W42, and W43 in FIG. 11, the reinforcing member 42 has its butt-jointed portions welded to the inner surface 211a of the end face portion 211, the inner surface 221a of the side face portion 221, and the upper mounting portion 223T and lower mounting portion 223B of the side beam 22L.

At this time, the weld bead of the backing metal 41 is not formed outside the recess 411. Therefore, the reinforcing member 42 can be joined to the end sill 21 and the side sill 22L without having to remove the weld bead of the backing metal 41. This completes the assembly of the corner portion C of the underframe 2.

(Assembly of the body)
The carbody 6 has end structures 4, each having corner posts 7 fixed to its end in the vehicle width direction Y, connected to the front and rear ends of the underframe 2. The side structures 3, for example, have their front ends connected to the end structures 4 via the corner posts 7, and their lower ends connected to the underframe 2. The roof structure 5 is connected to the end structures 4 connected to the underframe 2 and to the upper ends of the side structures 3.

In this embodiment, the corner member 23 and corner post 7 are formed by cutting a single extrusion molded product. Therefore, the car body 6 aligns the chamfered portion 71 of the corner post 7 with the chamfered portion 233 of the underframe 2, forming an attractive car body chamfered portion CH.

(Vehicle body destruction due to offset collision)
For example, the railway vehicle 1 may derail while traveling on a double track, causing a corner of the carbody 6 to collide with an oncoming vehicle traveling on the opposite track. The carbody 6 can absorb the collision load during an offset collision by using the carbody chamfered portion CH, thereby suppressing deformation.

Even though the corner members 23 of the underframe 2 are separate members from the end sills 21 and side sills 22L, the corner members 23 are firmly connected to the end sills 21 and side sills 22L via backing metals 41. Therefore, even if a collision load during an offset collision acts on the corner members 23, the underframe 2 is unlikely to fracture at the welded portions P1 between the end sills 21 and corner members 23 or at the welded portions P2 between the corner members 23 and side sills 22L.

The corner member 23 is supported from the back side by, for example, the upper mounting portion 223T and the lower mounting portion 223B of the side sill 22L. Therefore, even if a collision load acts on the corner member 23 during an offset collision, deformation of the corner member 23 is suppressed. Therefore, the corner portion C of the underframe 2 is less likely to deform during an offset collision.

As shown in Figure 3, the underframe 2 has a space S between the corner member 23 and the reinforcing member 42. This space S allows the underframe 2 to absorb collision loads during an offset collision, suppressing deformation of the corner portion C.

In the railway vehicle 1, deformation of the corner portion C of the underframe 2 is suppressed during an offset collision, thereby suppressing fracture of the joint between the underframe 2 and the side structure 3 and the joint between the underframe 2 and the end structure 4. As a result, the railway vehicle 1 can reduce compression of the interior space during an offset collision.

As described above, in the railway vehicle underframe structure of this embodiment, the partial welding positions of the backing metal 41 are clearly indicated by the recesses 411 formed in the backing metal 41, so there is no need to perform marking work to indicate the partial welding positions before welding the backing metal 41. Therefore, with the railway vehicle underframe structure of this embodiment, the assembly work of the corner portion C can be simplified, improving the productivity of the underframe 2.

The embodiments disclosed in this specification are merely examples and do not limit the present invention in any way. Naturally, the technology disclosed in this specification can be improved and modified in various ways without departing from the spirit of the invention. For example, the corner member 23 may be joined to the end beam 21 and side beam 22L by a method other than butt welding. For example, the shapes of the end beam 21, side beams 22L and 22R, and corner member 23 may differ from those in the above-described embodiment.

For example, the backing metal 41 may be partially welded along the entire inner edge of the recess 411. However, if the backing metal 41 is welded to a portion of the inner edge of the recess 411 that is away from the opening, the weld bead that occurs when the backing metal 41 is partially welded is less likely to form outside the recess 411 (long side end 412). This makes it less likely that weld beads that can interfere with subsequent processes will be generated when the backing metal 41 is welded, and reduces the effort required to remove the weld beads.

For example, the backing metal 41 may be a shape other than rectangular. The shape and number of the recesses 411 may differ from those in the above embodiment. For example, the recesses 411 may be formed in a shape other than rectangular, such as a semicircular shape. Also, for example, the backing metal 41 may be partially welded in a U-shape along the inner edge of the rectangular recesses 411. However, by line-welding the backing metal 41 along the bottom 411a of the rectangular recesses 411, it becomes easier to manage the weld length to suppress distortion due to welding. Because weld beads generated during partial welding of the backing metal 41 are less likely to form outside the recesses 411, the effort required to remove weld beads that interfere with subsequent processes is reduced.

For example, at least one or both of the lower plate 32 and the jack support plate 33 may be omitted. However, by attaching the lower plate 32 to the underside of the end beam 21, the rigidity of the front end of the underframe 2 can be increased. By attaching the jack support plate 33 to the underside of the corner portion C, the rigidity of the underframe 2 can be increased against the load acting on the corner portion C, for example, when a jack-up device is inserted into the corner portion C to lift the railway vehicle 1.

For example, the reinforcing member 42 may not be necessary. However, by connecting the reinforcing member 42 to the end sill 21 and the side sill 22L above the jack receiving plate 33 and reinforcing the mounting portion of the jack receiving plate 33, it is possible to prevent deformation of the corner portion C when, for example, inserting a jack-up device into the corner portion C to jack up the railway vehicle 1. Furthermore, by increasing the rigidity of the corner portion C with the reinforcing member 42, it is possible to prevent deformation of the corner portion C of the underframe 2 due to collision loads during an offset collision, etc.

The reinforcing member 42 may be shaped other than L-shaped, such as a rectangular pillar. Multiple L-shaped reinforcing members 42 may be stacked or spaced apart on the back side of the corner member 23. In this case, the reinforcing member 42 may be positioned with its bent portion facing the corner member 23. However, if the reinforcing member 42 is L-shaped, positioned above the jack support plate 33, and connected to the end beam 21 and side beam 22L at a position outside the recess 411 of the backing metal 41, the reinforcing member 42 can be attached while avoiding the welded portion of the backing metal 41, reducing the effort required to remove the weld bead that occurs when welding the backing metal 41.

For example, the corner members 23 may be manufactured separately from the corner posts 7. The assembly procedures for the underframe 2 and the car body 6 may differ from those in the above embodiment.

REFERENCE SIGNS LIST 1 Railway vehicle 2 Underframe 3 Side structure 4 End structure 5 Roof structure 21 End beam 22L Side beam 23 Corner member 33 Jack support plate 41 Backing 411 Recess 411a Bottom 42 Reinforcing member 233 Chamfered portion C Corner portion P1, P2 Welded portion

Claims (6)

In a railway vehicle underframe structure having chamfered portions at corners connecting side beams and end beams,
a corner member that is formed with the chamfered portion and that is butt-welded to the side beam and the end beam to form the corner portion;
backing metals that are respectively arranged and partially welded on the back side of the welded portion between the corner member and the side beam and the back side of the welded portion between the corner member and the end beam;
and
The backing metal is formed of a flat plate, and a recess is provided at each partial welding position.
The underframe structure for a railway vehicle is configured as follows. 2. The railway vehicle underframe structure according to claim 1,
The backing metal is welded to a portion of the inner edge of the recess away from the opening.
The underframe structure for a railway vehicle is configured as follows. 2. The railway vehicle underframe structure according to claim 1,
The recess is formed in a rectangular shape,
The backing metal is welded to the bottom of the recess.
The underframe structure for a railway vehicle is configured as follows. 2. The railway vehicle underframe structure according to claim 1,
a jack support plate fixed to the underside of the corner portion;
an L-shaped reinforcing member disposed above the jack support plate and connected to the end beam and the side beam at a position outside the recess of the backing metal;
having
The underframe structure for a railway vehicle is configured as follows. A railway vehicle comprising an underframe, side structures connected to both ends of the underframe in a vehicle width direction, end structures connected to both ends of the underframe in a vehicle length direction, and a roof structure connected to upper ends of the side structures and the end structures,
The underframe is
Side beams and
Edge beam and
corner members each having a chamfered portion and butt-welded to the side beam and the end beam to form a corner portion of the underframe;
backing metals that are respectively arranged and partially welded on the back side of the welded portion between the corner member and the side beam and the back side of the welded portion between the corner member and the end beam;
and
The backing metal is formed of a flat plate, and a recess is provided at each partial welding position.
A railway vehicle configured as follows: a corner member including a first joint portion and a second joint portion extending in directions perpendicular to each other in a top view, and a chamfered portion interposed between the first joint portion and the second joint portion so as to be inclined relative to the first joint portion and the second joint portion, the corner member being used in a railway vehicle underframe in which an end beam is butt-welded to the first joint portion and a side beam is butt-welded to the second joint portion, the backing metal being disposed on the back side of the welded portion between the side beam and the second joint portion or the back side of the welded portion between the first joint portion and the end beam,
The welding groove is formed of a flat plate and has a recess at each partial welding position.
A backing fund that is structured as follows: