Manufacturing method for railroad vehicle

Abstract

To provide a manufacturing method for a railroad vehicle that can shorten a working time for jointing hollow extruded shape materials, while suppressing a quality of a body structure formed of the hollow extruded shape materials welded and jointed from deteriorating.SOLUTION: A railroad vehicle is provided with a body structure 13 in which a jointed part 13AJ, in which a first jointed protrusion 40A of a first hollow extruded shape material 13A and a second jointed protrusion 40B of a second hollow extruded shape material 13A are jointed to each other while being butted to each other, is formed. The jointed part 13AJ includes welded metal 50 formed by performing CMT welding to a beveling 40C in a state where the beveling 40C of a predetermined angle is formed between the first jointed protrusion 40A and the second jointed protrusion 40B. The beveling angle of the beveling 40C is in a range of 23° or more and 37°or less.SELECTED DRAWING: Figure 5A

Description

[Technical Field]

[0001] The present invention relates to a railway vehicle having a structure formed by joining hollow extruded shapes by welding them together in a butt-jointed state. [Background technology]

[0002] Patent Document 1 discloses a railway vehicle having a structure formed by joining hollow extrusions by welding them together in a butt-fit state. In the railway vehicle according to Patent Document 1, end faces 21a, 22a of a connecting member 15 as a hollow extrusion and end faces 31a, 32a of a side structure 12 as a hollow extrusion are arranged to face each other in the up-down direction C, and grooves 41, 42 are formed between the end faces. Then, the connecting member 15 and the side structure 12 are joined by MIG (Metal Inert Gas) welding to the grooves 41, 42.

[0003] The applicant also joined hollow extrusions by arranging the end faces of the extrusions facing each other and MIG welding the groove formed between the end faces. For example, double-skinned hollow extrusions were placed on a jig with a liner plate between them, with the end faces butted together, and a groove was formed between the end faces. The double-skinned hollow extrusions were then joined by MIG welding the groove. The groove angle was 60°.

[0004] Furthermore, when MIG welding grooves, the volume of the molten pool differs between the welded side and the opposite side of the joint, so the amount of shrinkage on the welded side of the joint generally tends to be greater than on the opposite side. In particular, when using double-skin extrusions as hollow extrusions, welding is required on both the inside and outside of the vehicle, making it difficult to grasp the amount of deformation due to thermal shrinkage on the inside and outside of the vehicle. Therefore, the impact of differences in shrinkage was mitigated by MIG welding with a liner plate inserted between the double-skin extrusions, which creates a displacement (warp) in the opposite direction. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-140903 Summary of the Invention [Problem to be solved by the invention]

[0006] However, there were two issues. The first was that MIG welding involves a large amount of heat input during welding, which makes double-skin profiles susceptible to thermal deformation. The second was that, although the impact of differences in shrinkage was mitigated by using liner plates, the liner plates needed to be adjusted depending on the shape and dimensions of the hollow extrusions.

[0007] The present invention has been made to solve such problems, and aims to provide a railway vehicle that can reduce the time required to join hollow extrusions while suppressing a decrease in the quality of the structure formed by joining hollow extrusions by welding. [Means for solving the problem]

[0008] In order to achieve the above object, a railway vehicle according to one aspect of the present invention has the following features.

[0009] (1) A structure is provided in which a joint portion is formed in which a first joint protrusion of a first hollow extrusion and a second joint protrusion of a second hollow extrusion are joined in an abutting state, The joint includes a weld metal formed by CMT welding of a groove having a predetermined angle formed between the first joint projection and the second joint projection, The predetermined angle is in the range of 23° to 37°. According to the aspect described in (1) above, since the heat input of CMT welding is generally lower than that of MIG welding as a known technical knowledge, thermal deformation of the first hollow extrusion and the second hollow extrusion to be welded can be prevented, thereby suppressing quality degradation. Furthermore, since thermal deformation is prevented, it is not necessary to interpose a liner plate below the first hollow extrusion and the second hollow extrusion during welding, as is necessary with conventional MIG welding, so the joining time of the first hollow extrusion and the second hollow extrusion can be shortened. Moreover, when the bevel angle is in the range of 23° to 37°, quality degradation of the weld metal formed by welding can be suppressed.

[0010] (2) In the railway vehicle described in (1), the weld metal is formed to protrude on both sides in a direction perpendicular to the direction in which the first joint protrusion and the second joint protrusion are butted together, The length of the portion of the weld metal protruding toward the closed side of the groove in the direction of contact may be 0.5 to 1.0 times the length of the portion of the weld metal protruding toward the open side of the groove in the direction of contact. The aspect described in (2) above provides a well-balanced weld metal, which further reduces deterioration in the quality of the weld metal. (3) In the railway vehicle described in (1), the weld metal is formed to protrude on both sides in a direction perpendicular to the direction in which the first joint protrusion and the second joint protrusion are butted together, The length in the orthogonal direction of the portion of the weld metal that protrudes toward the closed side of the groove may be 0.2 to 1.0 times the length in the orthogonal direction of the portion of the weld metal that protrudes toward the open side of the groove. The aspect described in (3) above provides a well-balanced weld metal, which further reduces deterioration in the quality of the weld metal. [Effects of the Invention]

[0011] According to the present invention, it is possible to reduce the time required for joining hollow extrusions while suppressing deterioration in the quality of a structure formed by joining hollow extrusions by welding. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic side view of the vehicle as seen from the left side. [Figure 2] 2 is a schematic perspective view of the side structure disposed on the left side of FIG. 1 as viewed from the left rear vehicle exterior side. [Figure 3] FIG. 1 is an end view of an independent side structure forming member seen along the long side direction before being incorporated into the side structure. [Figure 4] 3 is an explanatory diagram for explaining a joint portion between side body structure forming members by extracting only the side body structure forming members relating to the view taken along the arrow AA in FIG. 2.

[0023] FIG. [Figure 5A] FIG. 5 is a partial enlarged view of part B in FIG. [Figure 5B] FIG. 5B is an explanatory diagram for explaining the width of a predetermined portion in FIG. 5A. [Figure 6] 3 is a partially enlarged cross-sectional end view of a joint portion taken along the arrow AA in FIG. 2. FIG. [Figure 7] 1 is a table showing evaluation results of a groove angle test. [Figure 8] Figure 8(A) is a photograph (left) of the appearance of the weld metal formed in the groove after CMT welding under specific conditions was performed on a groove with a groove angle of θ = 30°, and a cross-sectional photograph (right). Figure 8(B) is a photograph of the appearance of the weld metal formed in the groove after CMT welding under specific conditions was performed on a groove with a groove angle of θ = 60°. DETAILED DESCRIPTION OF THE INVENTION

[0013] First Embodiment Next, a railway vehicle according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a schematic side view of a railway vehicle (hereinafter referred to as "vehicle") according to a first embodiment of the present invention. For convenience, in FIG. 1, it is assumed that vehicle 1 travels to the left, and the left side of vehicle 1 traveling in the longitudinal direction (car body longitudinal direction) of car body 10 constituting vehicle 1 will be referred to as the "front side" and the right side opposite to the traveling left side as the "rear side." Furthermore, the right and left sides of vehicle body 10 when facing from the rear side to the front side in the car body longitudinal direction (car body width direction) will be referred to as the "right side" and "left side," respectively. Therefore, FIG. 1 is a schematic side view of vehicle 1 as seen from the left side.

[0014] The vehicle 1 will now be described. The vehicle 1 is an express vehicle. A body structure 10A forming the framework of a carbody 10 of the vehicle 1 includes an underframe 11 forming the floor of the carbody 10, a pair of end bodies 12 erected at both ends of the underframe 11 in the carbody longitudinal direction, a pair of side bodies 13 erected at both ends of the underframe 11 in the carbody width direction, and a roof body structure 14 that forms the roof of the carbody 10 by being disposed at the upper ends of the pair of end bodies 12 and the pair of side bodies 13. Note that in this embodiment, the vehicle 1 is an express vehicle as an example, but it may also be another type of railway vehicle such as a commuter vehicle.

[0015] Each side structure 13 is provided with an access opening 13h1 on the front and rear sides in the longitudinal direction of the car body. Each access opening 13h1 is formed in a vertically long rectangle. An access door 22 that can be opened and closed along the longitudinal direction of the car body is installed in the access opening 13h1. Furthermore, each side structure 13 is provided with a number of side window openings 13h2 that are arranged at equal intervals along the longitudinal direction of the car body. The side window openings 13h2 are formed in a substantially rectangular shape. A side window 23 is installed in each side window opening 13h2.

[0016] Next, the side structure 13 will be described. FIG. 2 is a schematic perspective view of the side structure 13 arranged on the left side of FIG. 1, as viewed from the left rear vehicle exterior side. As shown in FIG. 2, the side structure 13 is formed by first side structure forming member 13A1 to seventh side structure forming member 13A7 being arranged from top to bottom without any gaps and joined together with weld metal 50 formed by CMT (Cold Metal Transfer) welding under specific conditions described below. Note that, hereinafter, the first side structure forming member 13A1 to seventh side structure forming member 13A7 will be collectively referred to as "side structure forming member 13A." Furthermore, the number of side structure forming members 13A constituting the side structure 13 is not particularly limited and may be changed as appropriate.

[0017] Although the structures of the first to seventh side body structure forming members 13A1 to 13A7 differ strictly depending on whether or not they have an opening 13h1 for boarding and alighting and whether or not they have a side window opening 13h2, the first to seventh side body structure forming members 13A1 to 13A7 share a common basic structure. The first to seventh side body structure forming members 13A1 to 13A7 have the same long-side length, short-side length, and thickness, as well as the same main components. Therefore, for the sake of convenience, the basic structures of the first to seventh side body structure forming members 13A1 to 13A7 will be described below in a summarized form, to the extent that it does not cause any particular inconvenience.

[0018] The side body structure forming members 13A are extruded hollow members made of aluminum alloy. The side body structure forming members 13A are formed into an overall rectangular shape and extend the entire length of the side body structure 13 in the longitudinal direction of the car body. The extrusion direction of the side body structure forming members 13A is the same as the long side direction of the side body structure forming members 13A. Each side body structure forming member 13A is joined to another side body structure forming member 13A over the entire length of the car body in the longitudinal direction by weld metal 50 formed by CMT welding under specific conditions. A joint joint 13AJ is formed at each joint. The specific conditions for CMT welding will be described later.

[0019] Next, the basic structure of the side structure forming member 13A and the basic structure of the joint joint 13AJ will be described using Figures 3 to 6. Figure 3 is a side view of an independent side structure forming member 13A before it is incorporated into the side structure 13, as viewed along the long side, and Figure 4 is an explanatory diagram for explaining the joint portion between the side structure forming members 13A, extracting only the side structure forming members 13A at the joint portion shown in the view along arrow AA in Figure 2. Figure 5A is a partially enlarged view of portion B in Figure 4, Figure 5B is an explanatory diagram for explaining the width of a predetermined portion in Figure 5A, and Figure 6 is a partially enlarged cross-sectional end view of the joint portion shown in the view along arrow AA in Figure 2.

[0020] 3 to 6, for convenience, the vertical and horizontal directions shown in Figures 3 to 6 are used to describe the basic structure of the side body structure forming material 13A and the basic structure of the joint joint 13AJ, but these directions do not define the actual directions. Note that the vertical direction is also the thickness direction of the side body structure forming material 13A (the width direction of the car 1), the horizontal direction is also the short side direction of the side body structure forming material 13A (the height direction of the car 1), and the direction perpendicular to the paper surface is also the long side direction of the side body structure forming material 13A (the extrusion molding direction).

[0021] As shown in FIG. 3, the side structure forming member 13A is made of a double-skin profile member and includes an upper side panel 40, a lower side panel 41, end ribs 42, a central rib 43, an upper support protrusion 44, and a lower support protrusion 45.

[0022] The upper side plate 40 and the lower side plate 41 are formed so as to be separated in the vertical direction. End ribs 42 and a central rib 43 are interposed between the upper side plate 40 and the lower side plate 41. The end ribs 42 are formed near both left and right ends between the upper side plate 40 and the lower side plate 41, and a plurality of central ribs 43 are formed over almost the entire left and right area between both end ribs 42. The upper side plate 40 and the lower side plate 41 are connected by the end ribs 42 and the central rib 43.

[0023] The end ribs 42 are perpendicular to both the upper side panel 40 and the lower side panel 41. The multiple central ribs 43 are inclined relative to the up-down direction. More specifically, the multiple central ribs 43 are configured so that adjacent ribs in the left-right direction are symmetrical to each other (zigzag and inclined), in other words, in a truss structure. Note that, although the multiple central ribs 43 are configured in a truss structure as an example, they may also be configured in other structures such as a harmonica structure.

[0024] In the following, the side of the lower side plate 41 in the vertical direction relative to the upper side plate 40 will be referred to as the "vertical inner side," and the side opposite the lower side plate 41 in the vertical direction will be referred to as the "vertical outer side." Similarly, the side of the upper side plate 40 in the vertical direction relative to the lower side plate 41 will be referred to as the "vertical inner side," and the side opposite the upper side plate 40 in the vertical direction will be referred to as the "vertical outer side." In other words, in the side structure forming material 13A, the direction from both ends in the vertical direction toward the vertical center will be referred to as the "vertical inner side," and the direction from the vertical center toward both ends in the vertical direction will be referred to as the "vertical outer side."

[0025] Furthermore, in the side structure forming material 13A, the side of one end in the left-right direction relative to the other end is referred to as the "inner side in the left-right direction," and the side opposite the other end in the left-right direction relative to the other end is referred to as the "outer side in the left-right direction." That is, in the side structure forming material 13A, the direction from both ends in the left-right direction toward the center in the left-right direction is referred to as the "inner side in the left-right direction," and the direction from the center in the left-right direction toward both ends in the left-right direction is referred to as the "outer side in the left-right direction."

[0026] Both left and right ends of the upper side panel 40 and the lower side panel 41 are formed to protrude outward in the left-right direction from the end rib 42. Hereinafter, the portion of the upper side panel 40 on one side (the right side in FIG. 3 ) that protrudes from the end rib 42 will be referred to as the "upper right-hand joining protrusion 40A," and the portion of the upper side panel 40 on the other side (the left side in FIG. 3 ) that protrudes from the end rib 42 will be referred to as the "upper left-hand joining protrusion 40B." Similarly, the portion of the lower side panel 41 on one side (the right side in FIG. 3 ) that protrudes from the end rib 42 will be referred to as the "lower right-hand joining protrusion 41A," and the portion of the lower side panel 41 on the other side (the left side in FIG. 3 ) that protrudes from the end rib 42 will be referred to as the "lower left-hand joining protrusion 41B." Note that in the first embodiment, the upper right-hand joining protrusion 40A, the upper left-hand joining protrusion 40B, the lower right-hand joining protrusion 41A, and the lower left-hand joining protrusion 41B have the same left-right length.

[0027] The end faces of the upper right joint projection 40A (upper right end face 40A1), the upper left joint projection 40B (upper left end face 40B1), the lower right joint projection 41A (lower right end face 41A1), and the lower left joint projection 41B (lower left end face 41B1) are formed flat. Specifically, in a cross section perpendicular to the long side direction of the side structure forming member 13A (cross section perpendicular to the forming member), the upper right end face 40A1, the upper left end face 40B1, the lower right end face 41A1, and the lower left end face 41B1 are inclined inward in the left-right direction as they extend outward in the up-down direction. The inclination angles of the upper right end face 40A1, the upper left end face 40B1, the lower right end face 41A1, and the lower left end face 41B1 relative to the up-down direction are all 15°.

[0028] An upper bearing protrusion 44 is formed on the inner surface (upper right inner surface 40A2) of the upper right joint protrusion 40A near its tip. Details of the upper bearing protrusion 44 will be described later. The upper bearing protrusion 44 is formed to be vertically inward of the upper right inner surface 40A2 and protrude outward in the left-right direction from the tip of the upper right joint protrusion 40A. Meanwhile, a lower bearing protrusion 45 is formed on the inner surface (lower right inner surface 41A2) of the lower right joint protrusion 41A near its tip. Details of the lower bearing protrusion 45 will be described later. The lower bearing protrusion 45 is formed to be vertically inward of the lower right inner surface 41A2 and protrude outward in the left-right direction from the tip of the lower right joint protrusion 41A. Therefore, the upper bearing protrusion 44 and the lower bearing protrusion 45 face each other in the up-down direction. Furthermore, the shapes of the upper bearing protrusion 44 and the lower bearing protrusion 45 are vertically symmetrical.

[0029] Next, we will explain the upper and lower bearing projections 44 and 45, as well as the joint joint 13AJ, which is the joining structure between the side structure forming members 13A. Note that the shapes of the upper and lower bearing projections 44 and 45 are symmetrical from top to bottom, so a detailed explanation of the lower bearing projection 45 will be omitted.

[0030] In the side structure 13, the side structure forming members 13A are joined in a state where they face the same direction along the short side. In other words, between the joined side structure forming members 13A, the upper right joining protrusion 40A of one side structure forming member 13A abuts against the upper left joining protrusion 40B of the other side structure forming member 13A, and the lower right joining protrusion 41A of one side structure forming member 13A abuts against the lower left joining protrusion 41B of the other side structure forming member 13A.

[0031] In detail, the inner vertical tip (bottom end of the upper right end face) 40A12 of the upper right end face 40A1 and the inner vertical tip (bottom end of the upper left end face) 40B12 of the upper left end face 40B1 abut against each other, and the inner vertical tip (bottom end of the lower right end face) 41A12 of the lower right end face 41A1 and the inner vertical tip (bottom end of the lower left end face) 41B12 of the lower left end face 41B1 abut against each other.

[0032] The upper right end face 40A1 and the upper left end face 40B1 form an upper groove 40C that increases in width (length in the left-right direction) as it extends outward in the vertical direction, and that is open on the outside in the vertical direction and closed on the inside in the vertical direction. Similarly, the lower right end face 41A1 and the lower left end face 41B1 form a lower groove 41C that increases in width (length in the left-right direction) as it extends outward in the vertical direction, and that is open on the outside in the vertical direction and closed on the inside in the vertical direction. In the first embodiment, the angle α1 of the upper groove 40C (upper groove angle) and the angle α2 of the lower groove 41C (lower groove angle) are 30°.

[0033] When the side structure forming members 13A are butted against each other, the upper receiving projection 44 fits into the inside of the upper left joining projection 40B in the vertical direction, and the lower receiving projection 45 fits into the inside of the lower left joining projection 41B in the vertical direction.

[0034] The upper support projection 44 has a base end connected to a portion slightly inward in the left-right direction from the bottom end 40A12 of the upper right end face, an inner leg extending inward in the up-down direction, a bottom extending outward in the left-right direction from the inner end of the inner leg, and an outer leg extending outward in the up-down direction from the outer end of the bottom, with the tip of the outer leg positioned slightly inward in the up-down direction from the base end, forming a substantially C-shape (groove shape). The upper support projection 44 has an upper groove 44A (described in detail later) formed along the long side of the side structure forming member 13A, and both ends in the long side direction are open.

[0035] The upper groove portion 44A has an inner wall surface portion 44A1, a bottom surface portion 44A2, and an outer wall surface portion 44A3. The inner wall surface portion 44A1 is smoothly connected to the upper right inner surface 40A2 and is generally formed parallel to the up-down direction in the cross section perpendicular to the forming material. The bottom surface portion 44A2 is smoothly connected to the inner end of the inner wall surface portion 44A1 in the up-down direction and is generally formed parallel to the left-right direction in the cross section perpendicular to the forming material. The outer wall surface portion 44A3 is smoothly connected to the outer end of the bottom surface portion 44A2 in the left-right direction and is generally formed parallel to the up-down direction in the cross section perpendicular to the forming material.

[0036] Furthermore, when the side structure forming members 13A are butted against each other, the upper groove 44A straddles in the left-right direction between the upper right joint protrusion 40A associated with the upper groove 44A and the upper left joint protrusion 40B that is butted against the upper right joint protrusion 40A. In detail, the upper groove 44A is formed from the outer tip of the upper left end face 40B1 in the vertical direction (top edge 40B11 of the upper left end face) to the outer side in the left-right direction as viewed from the upper right joint protrusion 40A (inner side in the left-right direction as viewed from the upper left joint protrusion 40B).

[0037] The width W11 between the junction (junction location) P1 between the butted upper right joining projection 40A (bottom edge 40A12 of the upper right end face) and the butted upper left joining projection 40B (bottom edge 40B12 of the upper left end face) and the innermost location (innermost groove location) P2 of the inner wall surface portion 44A1 in the left-right direction is longer than the width W12 between the innermost groove location P2 and the outermost tip of the upper right end face 40A1 in the up-down direction (top edge 40A11 of the upper right end face). In other words, in the range between the junction location P1 and the top edge 40A11 of the upper right end face in the left-right direction, the width of the portion where the upper groove portion 44A is formed is wider than the width of the portion where the upper groove portion 44A is not formed.

[0038] In addition, a portion of the upper groove portion 44A is formed laterally outward of the top edge 40B11 of the upper left end surface of the upper left joining protrusion 40B that abuts against the upper right joining protrusion 40A related to the upper groove portion 44A.

[0039] In the left-right direction, width W21 between joint point P1 and top edge 40B11 of upper left end face is longer than width W22 between top edge 40B11 of upper left end face and the outermost point of upper groove portion 44A in the left-right direction, i.e., the outermost point of outer wall portion 44A3 in the left-right direction (groove outermost point P3). In other words, the width of the portion of upper groove portion 44A that is within the range of upper left end face 40B1 is wider than the width of the portion of upper groove portion 44A that is not within the range of upper left end face 40B1.

[0040] Thus, the upper groove 44A is positioned slightly outward in the left-right direction from the welded portion P1. In other words, it is positioned eccentrically outward in the left-right direction from the range of the upper groove 40C. This is to ensure that a sound weld joint can be obtained (a molten pool can be accumulated) within the range of the upper groove 44A even if a root gap occurs in the upper groove 40C. However, because width W11 is wider than width W12 and width W21 is wider than width W22, the upper groove 44A is positioned generally not eccentrically in the left-right direction from the range of the upper groove 40C and is within the range of the upper groove 40C.

[0041] Since the inner wall surface portion 44A1 is generally parallel to the vertical direction in the cross section perpendicular to the forming material, the innermost portion P2 of the groove is any portion of the inner wall surface portion 44A1. Similarly, since the outer wall surface portion 44A3 is generally parallel to the vertical direction in the cross section perpendicular to the forming material, the outermost portion P3 of the groove is any portion of the outer wall surface portion 44A3.

[0042] Additionally, an upper dam portion 44B is formed laterally outward of the outer wall surface 44A3 of the upper support projection 44 and vertically outward of the bottom surface 44A2. The upper dam portion 44B blocks the molten pool that flows into the upper groove 44A when CMT welding is performed on the upper groove 40C under specific conditions, as described below. In other words, the upper support projection 44, which includes the upper groove 44A and the upper dam portion 44B, functions as a pocket for storing the molten pool. The vertically outer surface of the upper dam portion 44B (the upper dam portion outer surface 44B1) is formed parallel to the horizontal direction in the cross section perpendicular to the forming material.

[0043] The upper dam portion 44B faces, at a slight distance from, the upper left joining protrusion 40B, which abuts against the upper right joining protrusion 40A associated with the upper dam portion 44B. That is, a gap S1 is formed between the upper dam portion outer surface 44B1 and the inner surface (upper left inner surface 40B2) of the upper left joining protrusion 40B in the vertical direction.

[0044] 5A illustrates the joint between side structure forming members 13A before CMT welding under specific conditions, but in the completed state of side structure 13, CMT welding under specific conditions is performed from the outside in the vertical direction on upper groove 40C and lower groove 41C. FIG. 6 illustrates the state in which CMT welding under specific conditions is performed on butted side structure forming members 13A shown in FIG. 5A, and weld metal 50 is formed between upper right joint projection 40A and upper left joint projection 40B. Note that, similar to FIG. 6, weld metal 50 is also formed between butted lower right joint projection 41A and lower left joint projection 41B.

[0045] As shown in Figure 6, the weld metal 50 is formed not only within the range of the upper right joint protrusion 40A and the upper left joint protrusion 40B in the vertical direction (the upper right end face 40A1 and the upper left end face 40B1, or the upper groove 40C, that were formed before CMT welding), but also protrudes outward in the vertical direction from the upper right joint protrusion 40A and the upper left joint protrusion 40B (the upper right end face 40A1 and the upper left end face 40B1, or the upper groove 40C, that were formed before CMT welding), and also protrudes inward in the vertical direction from the upper right joint protrusion 40A and the upper left joint protrusion 40B (the upper right end face 40A1 and the upper left end face 40B1, or the upper groove 40C, that were formed before CMT welding). Hereinafter, the weld metal 50 of the portion formed within the range of the upper right end face 40A1 and the upper left end face 40B1 (formed before CMT welding) in the vertical direction (between the outer surfaces of the upper right joint protrusion 40A and the upper left joint protrusion 40B in the vertical direction and the upper right inner surface 40A2 and the upper left inner surface 40B2) will be referred to as the "central weld metal 50A." The weld metal 50 in the portion formed on the outer side (the portion protruding from the outer vertical surfaces of the upper right joint protrusion 40A and the upper left joint protrusion 40B) is referred to as the "outer weld metal 50B," and the weld metal 50 in the portion formed on the inner vertical side of the upper right end face 40A1 and the upper left end face 40B1 (formed before CMT welding) (the portion on the inner vertical side of the upper right inner face 40A2 and the upper left inner face 40B2) is referred to as the "inner weld metal 50C."

[0046] Since an upper groove 44A is formed directly below the inside of the upper groove 40C in the vertical direction, when CMT welding is performed on the upper groove 40C under specific conditions and a molten pool flows into the upper groove 44A, inner weld metal 50C is formed inside the upper groove 44A. Note that it is sufficient that the weld metal 50 penetrates at least up to the joint location P1, so inner weld metal 50C does not have to be formed. Alternatively, inner weld metal 50C may be filled into the upper groove 44A.

[0047] The left-right length W31 of the outer weld metal 50B is greater than the left-right length W32 of the inner weld metal 50C, i.e., the left-right length W32 of the upper groove portion 44A. Specifically, the left-right length W32 of the inner weld metal 50C, i.e., the left-right length W32 of the upper groove portion 44A, is approximately two-thirds of the left-right length W31 of the outer weld metal 50B. Furthermore, the up-down length H31 of the outer weld metal 50B is approximately the same as the up-down length H32 of the inner weld metal 50C, i.e., the up-down length H32 of the upper groove portion 44A.

[0048] In the test described below, when CMT welding was performed under specific conditions on a test piece 60 that did not have an upper support projection 44, it was concluded that the preferred groove angle was 30°. However, since the preferred groove angle differs depending on the plate thickness, the preferred groove angle is 30°±7°.

[0049] Furthermore, when the test piece 60, on which the upper support projection 44 is not formed, has a 30° groove angle, the weld metal is formed to protrude downward and upward of the test piece 60. Therefore, in the side structure forming material 13A, in order to make the shape of the inner weld metal 50C constant, at least the area of ​​the upper groove portion 44A in the forming material orthogonal cross section is set smaller than the area of ​​the weld metal formed to protrude downward in the orthogonal cross section of the test piece 60 formed with a 30° groove angle. That is, the upper groove portion 44A is formed so that the inner weld metal 50C is filled in the upper groove portion 44A when the side structure 13 is completed. Furthermore, as will be described later, the width of the weld metal formed to protrude downward in the test piece 60 formed with a 30° groove angle is approximately two-thirds the width of the weld metal formed to protrude upward, and the height of the weld metal formed to protrude downward is approximately the same as the height of the weld metal formed to protrude upward. Therefore, working backwards, it is preferable that the left-right width W32 and the up-down height H32 of the upper groove portion 44A are approximately the same as the width and height of the weld metal formed protruding downward from the test piece 60, which is formed with a groove angle of 30°, as described below.

[0050] However, for example, the relationship between the vertical length H31 of the outer weld metal 50B and the vertical length H32 of the inner weld metal 50C (upper groove portion 44A) and the relationship between the left-right length W31 of the outer weld metal 50B and the left-right length W32 of the inner weld metal 50C (upper groove portion 44A) may be changed as appropriate within a range that maintains a balanced weld metal structure. For example, the vertical length H32 of the inner weld metal 50C may be changed as appropriate within a range from 0.5 to 1.0 times the vertical length H31 of the outer weld metal 50B. Furthermore, the left-right length W32 of the inner weld metal 50C may be changed as appropriate within a range from 0.5 to 1.0 times the left-right length W31 of the outer weld metal 50B.

[0051] In this way, in the side structure 13, the side structure forming members 13A are in a state where the upper right joint projection 40A and the lower right joint projection 41A are butted against the upper left joint projection 40B and the lower left joint projection 41B, and the upper support projection 44 extends up and down into the upper left joint projection 40B and the lower support projection 45 extends up and down into the lower left joint projection 41B. In this state, weld metal 50 is formed not only between the upper right joint projection 40A and the upper left joint projection 40B and between the lower right joint projection 41A and the lower left joint projection 41B, but also on the up and down outer and inner sides, thereby joining the side structure forming members 13A to each other. When such side structure forming members 13A are joined together, the inner left-right ends (bases) of the upper right joining protrusion 40A and the lower right joining protrusion 41A, and the outer left-right ends (bases) of the upper left joining protrusion 40B and the lower left joining protrusion 41B constitute the joining joint 13AJ of the side structure forming member 13A.

[0052] Next, we will explain Test 1 (groove angle test), which verified the applicability of groove angles for joining hollow extrusions by CMT welding under specific conditions, and Test 2 (tensile strength test), which verified the effectiveness of the optimal groove angle obtained from Test 1.

[0053] (Test 1: Groove angle test) First, we will explain the groove angle test. In the groove angle test, a pair of two test pieces 60 was prepared for each groove angle. The test pieces 60 were rectangular plates made of aluminum alloy, and the thickness of the test pieces 60 was 3 mm. The two test pieces 60 were then butted together along the short side direction, and CMT welding was performed under specific conditions on the groove formed at the butted point. The quality and workability of the weld metal 61 produced by CMT welding were evaluated. Five groove angles θ were verified in the groove angle test: 0°, 15°, 30°, 45°, and 60°.

[0054] The specific conditions for CMT welding are that the welding machine used is a known specific welding machine (TPS5000CMT, manufactured by Fronius), that the welding speed is a specific welding speed, and that the welding current is a specific welding current.

[0055] Here, the specific welding speed and specific welding current will be explained. While detailed explanations are omitted, the applicant previously set the groove angle of the double-skin section constituting the side structure of a railway vehicle to 60° in the manufacture of the side structure, and performed MIG welding on the groove at a specific welding speed and a specific welding current. In this case, the quality of the weld metal 61 was better under the specific welding speed and specific welding current than under other groove angles. This specific welding speed and specific welding current are included in the specific conditions. The double-skin section constituting the side structure was made of aluminum alloy, and the thickness of the joints of the double-skin section constituting the side structure (portions corresponding to the upper right joint projection 40A, lower right joint projection 41A, upper left joint projection 40B, and lower left joint projection 41B of the side structure forming member 13A) was 3 mm.

[0056] In the groove angle test, a known specific welding machine was installed on a known portal traveling machine (not shown) in a state in which it straddled two test pieces 60 that were arranged in a butted state along the short side direction. Then, by running the portal traveling machine along the groove, CMT welding was performed on the groove under specific conditions.

[0057] The evaluation method consisted of first conducting an individual evaluation for each evaluation item, and then conducting an overall evaluation that comprehensively considered the results of each individual evaluation. The evaluation items were categorized into quality and workability. The quality evaluation items were penetration depth, excess fill, and holes, and the workability evaluation item was whether the groove could be recognized using a portal-type traveling machine.

[0058] The evaluation results of the groove angle test for each groove angle θ are shown in Fig. 7. The results of the individual and overall evaluations are expressed in three levels: "Good (〇)", "Average (△)", and "Poor (×)".

[0059] As shown in Figure 7, for a groove angle θ = 30°, the individual evaluations for all evaluation items were "Good," so the overall evaluation was "Good." For a groove angle θ = 15°, the individual evaluation for perforation was "Good," but the other individual evaluations were "Good," with no "Poor" evaluations, so the overall evaluation was "Good." For a groove angle θ = 45°, the individual evaluations for two evaluation items (penetration depth and workability) were "Good," but the individual evaluations for perforation and the individual evaluations for reinforcement were "Poor." Therefore, the overall evaluation was "Poor" from a quality perspective. For a groove angle θ = 60°, the individual evaluations for two evaluation items (penetration depth and workability) were "Good," but the individual evaluations for reinforcement and perforation were "Poor." Therefore, the overall evaluation was "Poor" from a quality perspective. For a groove angle θ = 0°, the individual evaluation for perforation was "Good," but the other individual evaluations were "Poor," so the overall evaluation was "Poor."

[0060] As mentioned above, conventionally, when MIG welding was performed with a groove angle of 60° at a specific welding speed and a specific welding current, the quality of the weld metal 61 was good, but when CMT welding was performed under specific conditions, including a groove angle of 60°, a specific welding speed, and a specific welding current, the individual evaluations of reinforcement and pitting were "x." Therefore, when performing CMT welding under specific conditions, a groove angle of 60° is considered completely inappropriate.

[0061] FIG. 8(A) is a photograph (left side) of the appearance of weld metal 61 formed in a groove after CMT welding under specific conditions was performed on a groove with a groove angle θ = 30°, and a cross-sectional photograph (right side) of weld metal 61 formed in a groove after CMT welding under specific conditions was performed on a groove with a groove angle θ = 60°.

[0062] Based on the above, the evaluation results of the groove angle test showed that the groove angle θ was best in the order of 30° > 15° > 45°, and 60° > 0°. Furthermore, because penetration depth and excess fill tend to change linearly when the groove angle θ is used as a parameter, it is thought that groove angles θ in the range of 23° to 37° are applicable. Alternatively, considering that the individual evaluation for a groove angle θ of 15° was "△," it is also thought that groove angles θ in the range of 20° to 37° are applicable.

[0063] Furthermore, although not shown, the lower side of the groove (the side opposite to the welded side) formed in the test piece 60 for the groove angle test does not have the upper support protrusion 44 or the lower support protrusion 45, as in the side structure forming material 13A described above. Therefore, the shape of the portion of the weld metal 61 formed on the lower side of the test piece 60 is not restricted. Under these conditions, when the groove angle θ was 30°, the maximum protrusion amount H41 (thickness) of the portion of the weld metal 61 protruding upward from the test piece 60 was approximately the same as the maximum protrusion amount H42 (thickness) of the portion of the weld metal 61 protruding downward from the test piece 60. Furthermore, the maximum width W42 of the portion of the weld metal 61 protruding downward from the test piece 60 was approximately two-thirds of the maximum width W41 of the portion of the weld metal 61 protruding upward from the test piece 60. Therefore, paradoxically, the specific welding speed and specific welding current related to the specific conditions are those welding speed and welding current that, when CMT welding is performed using a known specific CMT welding machine in a situation where there is nothing on the lower side of a groove with a groove angle of 30° that restricts the shape of the portion protruding downward of the weld metal 61, such as the upper receiving protrusion 44 or the lower receiving protrusion 45, the maximum protrusion amount H42 (thickness) of the portion protruding upward of the weld metal 61 is approximately the same as the maximum protrusion amount H41 (thickness) of the portion protruding upward of the weld metal 61, and that the maximum width W42 of the portion protruding downward of the weld metal 61 is approximately 2 / 3 of the maximum width W41 of the portion protruding upward of the weld metal 61.

[0064] (Test 2: Tensile strength test) Next, we will explain the tensile strength test. In the tensile strength test, the tensile strength of a test piece (CMT test piece) containing a weld metal (joint) formed by CMT welding under specific conditions and the tensile strength of a test piece (MIG test piece) containing a weld metal (joint) formed by MIG welding under specific conditions are measured and compared.

[0065] The CMT test specimens and MIG test specimens are taken from a pair of test pieces 60 used in the groove angle test. Specifically, four CMT test specimens are taken from a single CMT test panel in which two test pieces 60 formed so that the groove angle θ is 30° are arranged in a butted state along the short side direction, and the groove formed by the butting together is joined with the weld metal (CMT weld metal) formed by CMT welding under specific conditions on the groove formed by the butting together. On the other hand, four MIG test specimens are taken from a single MIG test panel in which two test pieces 60 formed so that the groove angle θ is 60° are arranged in a butted state along the short side direction, and the groove formed by the butting together is joined with the weld metal (MIG weld metal) formed by MIG welding under specific conditions on the groove formed by the butting together.

[0066] The results of the tensile strength test showed that the average tensile strength of the four CMT test pieces (CMT average value) was higher than the average tensile strength of the four MIG test pieces (MIG average value). Specifically, the CMT average value was 3 to 4% higher than the MIG average value. Therefore, from the perspective of tensile strength, it is considered that there is no problem with performing CMT welding under specific conditions on a groove with a groove angle θ of 30°.

[0067] As described above, the vehicle 1 is provided with a side structure 13 (structure) in which a joint joint 13AJ (joint) is formed in which the upper right-side joining protrusion 40A and the lower right-side joining protrusion 41A (first joining protrusions) of the side structure forming member 13A (first hollow extruded profile) are joined in a butt-to-butt state with the upper left-side joining protrusion 40B and the lower left-side joining protrusion 41B (second joining protrusions) of the side structure forming member 13A (second hollow extruded profile), and the joint joint 13AJ (joint) includes weld metal 50 formed by CMT welding of an upper groove 40C and a lower groove 41C (groove) of a predetermined angle formed between the upper right-side joining protrusion 40A, etc. (first joining protrusion) and the upper left-side joining protrusion 40B, etc. (second joining protrusion), and the predetermined angle is in the range of 23° to 37°. Generally, as a known technical knowledge, the heat input of CMT welding is lower than that of MIG welding, so thermal deformation of the side structure forming members 13A (first hollow extrusion, second hollow extrusion) to be welded can be prevented, thereby suppressing quality degradation. Furthermore, by preventing thermal deformation, it is also unnecessary to interpose a liner plate below the side structure forming members 13A (first hollow extrusion, second hollow extrusion) during welding, so the joining work time for the side structure forming members 13A (first hollow extrusion, second hollow extrusion) can be shortened. Moreover, when the bevel angle is in the range of 23° to 37°, quality degradation of the weld metal 50 formed by welding can be suppressed.

[0068] Furthermore, according to vehicle 1, weld metal 50 is formed to protrude in the vertical direction (on both sides in the direction perpendicular to the direction in which the first and second joint projections butt together), and the left-right width W32 of inner weld metal 50C (the portion of the weld metal protruding toward the closed side of the groove) is 0.5 to 1.0 times the left-right width W31 of outer weld metal 50B (the portion of the weld metal protruding toward the open side of the groove). Therefore, deterioration in the quality of weld metal 50 can be suppressed.

[0069] Furthermore, according to vehicle 1, weld metal 50 is formed to protrude in the vertical direction (on both sides in a direction perpendicular to the direction in which the first and second joint projections butt together), and the vertical height H32 of inner weld metal 50C (the portion of the weld metal protruding toward the closed side of the groove) is 0.2 to 1.0 times the vertical height H31 of outer weld metal 50B (the portion of the weld metal protruding toward the open side of the groove). Therefore, deterioration in the quality of weld metal 50 can be suppressed.

[0070] Furthermore, as described above, the vehicle 1 includes the side structure 13 (structure) in which the upper right-side joint projection 40A and the lower right-side joint projection 41A (first joint projections) of the side structure forming member 13A (first hollow extruded shape member) are joined in a butted state to the upper left-side joint projection 40B and the lower left-side joint projection 41B (second joint projections) of the side structure forming member 13A (second hollow extruded shape member), and the joint joint 13AJ (joint) is formed. The weld metal 50 is formed by welding between the upper right joining projection 40A etc. (first joining projection) and the upper left joining projection 40B etc. (second joining projection), and on the surface opposite the side to be welded of the upper right joining projection 40A etc. (first joining projection) an upper receiving projection 44 and a lower receiving projection 45 (receiving projections) are formed to receive the molten pool that is the source of the weld metal 50, and the upper receiving projection 44 etc. (receiving projections) are formed to extend to the side opposite the side to be welded of the upper left joining projection 40B etc. (second joining projection) and have an upper groove portion 44A and a lower groove portion 45A (groove portion) for storing the molten pool. In the side structure 13, the side structure forming members 13A are joined together with the upper right joint protrusion 40A etc. (first joint protrusion) and the upper left joint protrusion 40B etc. (second joint protrusion) butting against each other. Furthermore, the upper right joint protrusion 40A etc. (first joint protrusion) is formed with the upper support protrusion 44 etc. (support protrusion) having the upper groove portion 44A etc. (groove portion) for storing the molten pool. This prevents a decrease in the weight balance in the butted direction of the joint joint 13AJ (joint). Furthermore, it prevents the welded portion from becoming eccentric from the center of the butted direction of the joint joint 13AJ (joint). Therefore, deterioration in the quality of the joint joint 13AJ (joint) can be suppressed.

[0071] Furthermore, the inner weld metal 50C is formed generally within the upper groove 44A (groove) that is not eccentric relative to the range of the upper groove 40C in the left-right direction and is positioned within the range of the upper groove 40C. This prevents the inner weld metal 50C from being formed eccentrically relative to the joint point P1 in the left-right direction, stabilizing the cross-sectional shape of the weld metal 50. Furthermore, the weld metal 50 is formed to protrude toward the welding side relative to the upper right joint protrusion 40A, etc. (first joint protrusion), and the cross-sectional area of ​​the upper groove 44A, etc. (groove) perpendicular to the extrusion direction of the side structure forming member 13A (first hollow extruded shape) is smaller than the cross-sectional area of ​​the outer weld metal 50B (portion of the weld metal formed to protrude toward the welding side relative to the first joint protrusion) perpendicular to the extrusion direction of the side structure forming member 13A (first hollow extruded shape). This further stabilizes the cross-sectional shape of the weld metal 50. Furthermore, the upper receiving projections 44 etc. (receiving projections) further have upper damming portions 44B (damming portions) that form outer wall surface portions 44A3 (side walls) of the upper groove portions 44A etc. (groove portions) near the upper left joining projections 40B etc. (second joining projections) to block the molten pool, and a gap S1 is formed between the upper damming portion 44B (damming portion) and the upper left joining projections 40B etc. (second joining projections). Therefore, the molten pool that does not fit into the upper groove portions 44A etc. (groove portions) can escape to the outside through the gap S1.

[0072] <Example of change> Next, a description will be given of modified examples of the vehicle 1 according to the first embodiment. The first embodiment described above can be modified as appropriate within the scope of the present invention.

[0073] In the first embodiment, the joining joint 13AJ is applied to joining the side structure forming members 13A that make up the side structure 13, but it may also be applied to joining the forming members that make up the underframe 11, the end structure 12, and the roof structure 14.

[0074] Furthermore, in the first embodiment, the side structure forming member 13A is made of a double-skin shape material, but it may be made of a hollow extrusion formed material having a structure other than a double-skin shape material, such as a single-skin shape material.

[0075] The shape of the upper groove portion 44A in a cross section perpendicular to the forming material may also be changed as appropriate. For example, the shape of either or both of the inner wall surface portion 44A1 and the outer wall surface portion 44A3 may be an arc shape that bulges outward from the center of the upper groove portion 44A in the left-right direction, or may be a shape other than a straight line parallel to the up-down direction.

[0076] The shapes of the upper and lower bearing projections 44 and 45 in a cross section perpendicular to the forming material may also be modified as appropriate, as long as they are formed, at least in the joined state, from the upper right inner surface 40A2 of the upper right joint projection 40A and the lower right inner surface 41A2 of the lower right joint projection 41A, extend outward in the left-right direction as a whole, and are recessed inward in the up-down direction of the upper left joint projection 40B and the lower left joint projection 41B. Furthermore, the shapes of the upper and lower bearing projections 44 and 45 in a cross section perpendicular to the forming material do not have to be symmetrical. For example, the thickness (plate thickness) of the upper and lower bearing projections 44 and 45 may be different. Furthermore, the left-right length of the upper and lower bearing projections 44 and 45 may be different.

[0077] The vertical height H32 of the inner weld metal 50C, i.e., the vertical height H32 of the upper groove portion 44A, may be changed as appropriate within a range of 0.2 to 1.0 times the vertical height H31 of the outer weld metal 50B. Furthermore, the left-right width W32 of the inner weld metal 50C, i.e., the left-right width W32 of the upper groove portion 44A, may be changed as appropriate within a range of 0.5 to 1.0 times the left-right width W31 of the outer weld metal 50B.

[0078] In terms of left-right length, the upper right-side joint protrusion 40A and the lower right-side joint protrusion 41A are substantially the same, and the upper left-side joint protrusion 40B and the lower left-side joint protrusion 41B are substantially the same, but either the upper right-side joint protrusion 40A or the lower right-side joint protrusion 41A may be longer, and either the upper left-side joint protrusion 40B or the lower left-side joint protrusion 41B may be longer, as long as the side structure forming members 13A can be joined without any gaps. However, it is more preferable that the upper right-side joint protrusion 40A and the lower right-side joint protrusion 41A are substantially the same, and the upper left-side joint protrusion 40B and the lower left-side joint protrusion 41B are substantially the same, because this positions the weld metal 50 closer to the center in the left-right direction at the joint 13AJ.

[0079] Similarly, the upper right-side joint protrusion 40A and the upper left-side joint protrusion 40B are approximately the same in left-right length, and the lower right-side joint protrusion 41A and the lower left-side joint protrusion 41B are approximately the same, but either the upper right-side joint protrusion 40A or the upper left-side joint protrusion 40B may be longer, and either the lower right-side joint protrusion 41A or the lower left-side joint protrusion 41B may be longer, as long as the side structure forming members 13A can be joined without any gaps. However, it is more preferable that the upper right-side joint protrusion 40A and the upper left-side joint protrusion 40B are approximately the same, and the lower right-side joint protrusion 41A and the lower left-side joint protrusion 41B are approximately the same, because this positions the weld metal 50 closer to the center in the left-right direction at the joint 13AJ.

[0080] The upper groove angle α1 of the upper groove 40C and the lower groove angle α2 of the lower groove 41C are 30°, but either or both do not have to be 30°. For example, either or both of the upper groove angle α1 and the lower groove angle α2 may be changed as appropriate within a range of 23° to 37°. Furthermore, provided that the upper groove angle α1 and the lower groove angle α2 are within a range of 23° to 37°, the inclination angle of the upper right end face 40A1 relative to the vertical direction and the inclination angle of the upper left end face 40B1 relative to the vertical direction do not have to be the same. Similarly, the inclination angle of the lower right end face 41A1 relative to the vertical direction and the inclination angle of the lower left end face 41B1 relative to the vertical direction do not have to be the same. That is, the inclination angle of upper right end face 40A1, upper left end face 40B1, lower right end face 41A1, and lower left end face 41B1 relative to the vertical direction does not have to be 15°.

[0081] It should be noted that the present embodiment is merely an example and does not limit the present invention in any way. Naturally, the present invention can be modified in various ways without departing from the spirit and scope of the present invention. [Explanation of symbols]

[0082] 1...railroad vehicle, 10...car body, 10A...structure 11... underframe, 12... gable body structure, 13... side body structure, 14... roof body structure 13A...Side structure forming material, 13AJ...Joint 40...Top side plate, 41...Bottom side plate, 42...End rib, 43...Central rib, 44...Upper receiving projection, 45...Lower receiving projection 40A...Top right joint protrusion, 40B...Top left joint protrusion, 41A...Bottom right joint protrusion, 41B...Bottom left joint protrusion, 40C...Top groove, 41C...Bottom groove 40A1...Top right end surface, 40A2...Top right inner surface, 40B1...Top left end surface, 40B2...Top left inner surface, 41A1...Bottom right end surface, 41A2...Bottom right inner surface, 41B1...Bottom left end surface, 41B2...Bottom left inner surface 40A11… Bottom end of upper right end face, 40A12… Bottom end of upper right end face, 40B11… Bottom end of upper left end face, 40B12… Bottom end of upper left end face, 41A11… Bottom end of lower right end face, 41A12… Bottom end of lower right end face, 41B11… Bottom end of lower left end face, 41B12… Bottom end of lower left end face 44…The upper side is protruding, 45…The lower side is protruding 44A…Upper ditch section, 44B…Upper weir stop section, 45A…Lower ditch section, 45B…Lower weir stop section 44A1…inner wall face, 44A2…bottom face, 44A3…outer wall face 50…welded metal, 50A…center welded metal, 50B…upper side welded metal, 50C…lower side welded metal

Claims

1. a structure in which a joint portion is formed in which a first joint protrusion of a first hollow extrusion and a second joint protrusion of a second hollow extrusion are joined in an abutting state; the joint includes a weld metal formed by CMT welding to a groove having a predetermined angle formed between the first joint projection and the second joint projection, A railway vehicle characterized in that the predetermined angle is in the range of 23° to 37°.

2. 2. The railway vehicle according to claim 1, The weld metal is formed to protrude on both sides in a direction perpendicular to the direction in which the first joint projection and the second joint projection are butted together, The length of the weld metal in the direction of abutment, of the portion of the weld metal protruding toward the closed side (lower side) of the groove, is 0.5 to 1.0 times the length of the weld metal in the direction of abutment, of the portion of the weld metal protruding toward the open side (upper side) of the groove.

3. 2. The railway vehicle according to claim 1, The weld metal is formed to protrude on both sides in a direction perpendicular to the direction in which the first joint projection and the second joint projection are butted together, a length in the orthogonal direction of the portion of the weld metal protruding toward the closed side (lower side) of the groove is 0.2 to 1.0 times the length in the orthogonal direction of the portion of the weld metal protruding toward the open side (upper side) of the groove.

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