Carriage frame and method for producing carriage frame

Abstract

A truck frame (30) for a railway vehicle includes a side beam (40) and a cross beam (50). The side beam (40) includes a top plate part (411), a bottom plate part (412), and an inner plate part (413) and an outer plate part (414) that connect the top plate part (411) and the bottom plate part (412) to each other. The cross beam (50) penetrates the inner plate part (413) and the outer plate part (414) and is joined to the inner plate part (413) and the outer plate part (414). The inner plate part (413) is divided into a first inner plate portion (413a) and a second inner plate portion. The first inner plate portion (413a) is a portion of the inner plate part (413) that is to be joined to the cross beam (50). The second inner plate portion is the other portion of the inner plate part (413) and is welded to the first inner plate portion (413a). The first inner plate portion (413a) is welded to the cross beam (50) at both an inner corner (51) and an outer corner (52) in a left-and-right direction.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a truck frame for a railway vehicle and a production method for the truck frame.BACKGROUND ART

[0002] A railway vehicle includes a truck that runs on rails and a vehicle body supported on the truck. The truck includes a truck frame, air springs disposed on the left and right sides of the truck frame, and wheel sets disposed on the front and rear sides of the truck frame. The air springs are disposed between the vehicle body and the truck frame to support the vehicle body. The truck frame is formed by a pair of left and right side beams that extend in the front-and-rear direction of the railway vehicle and a cross beam that extends in the left-and-right direction of the railway vehicle. Spring caps are provided at the front and rear ends of the left and right side beams. The spring cap houses an axle spring. The left and right side beams are each supported on the wheel sets via the spring caps and the axle springs.

[0003] A detailed configuration of the joints between the side beams and the cross beam of the truck frame is described in Patent Literature 1, for example. The truck frame described in Patent Literature 1 includes a pair of side beams and a pair of cross beams. Two through-holes are formed in a middle part of each side beam in the front-and-rear direction. Each cross beam is inserted into the through-hole from the inner face of the side beam (from the side of the center of the railway vehicle) and penetrates the side beam. After the cross beam is inserted into the side beam, the side beam and the cross beam are fillet-welded to each other from outside at the site of insertion.CITATION LISTPATENT LITERATURE

[0004] Patent Literature 1: Japanese Patent Application Publication No. 2021-151823SUMMARY OF INVENTIONTECHNICAL PROBLEM

[0005] In the railway vehicle, a motor is typically attached to the cross beam. The motor exerts a torsion stress on the cross beam. When a torsion stress is exerted on the cross beam, in general, the weld zone between the side beam and the cross beam is likely to be the most vulnerable to the stress in the truck frame. Therefore, there is a demand for improving the strength of the weld zone between the side beam and the cross beam.

[0006] An objective of the present disclosure is to provide a truck frame for a railway vehicle that is improved in strength of a weld zone between a side beam and a cross beam and a production method for the truck frame.SOLUTION TO PROBLEM

[0007] A truck frame for a railway vehicle according to the present disclosure includes a side beam and a cross beam. The side beam includes a top plate part, a bottom plate part opposed to the top plate part, and an inner plate part and an outer plate part that connect the top plate part and the bottom plate part to each other. The side beam extends in a front-and-rear direction of the railway vehicle. The cross beam extends in a left-and-right direction of the railway vehicle. The cross beam penetrates the inner plate part and the outer plate part and is joined to the inner plate part and the outer plate part. The inner plate part is divided into a first inner plate portion and a second inner plate portion. The first inner plate portion is a portion of the inner plate part that is to be joined to the cross beam. The second inner plate portion is the other portion of the inner plate part and is welded to the first inner plate portion. The first inner plate portion is welded to the cross beam at both an inner corner and an outer corner in the left-and-right direction.

[0008] A production method according to the present disclosure is a production method for the truck frame described above. The production method includes a first joining step and a second joining step. In the first joining step, the first inner plate portion and the cross beam are welded to each other. In the second joining step, after the first joining step, the first inner plate portion and the second inner plate portion are welded to each other.ADVANTAGEOUS EFFECTS OF INVENTION

[0009] With the truck frame and the production method for the truck frame according to the present disclosure, the strength of a weld zone between a side beam and a cross beam can be improved.BRIEF DESCRIPTION OF THE DRAWINGS

[0010] [FIG. 1] FIG. 1 is a schematic diagram showing a general configuration of a railway vehicle that includes a truck frame according to a first embodiment. [FIG. 2] FIG. 2 is a top view of the truck frame. [FIG. 3] FIG. 3 is a side view of the truck frame according to the first embodiment. [FIG. 4] FIG. 4 is a side view of the truck frame according to the first embodiment. [FIG. 5] FIG. 5 is a lateral cross-sectional view of the truck frame according to the first embodiment. [FIG. 6] FIG. 6 is a flowchart showing a production method for the truck frame according to the first embodiment. [FIG. 7] FIG. 7 is a schematic diagram showing the truck frame according to the first embodiment in the production process. [FIG. 8] FIG. 8 is a side view of a truck frame according to a second embodiment. [FIG. 9] FIG. 9 is a side view of the truck frame according to the second embodiment. [FIG. 10] FIG. 10 is a lateral cross-sectional view of the truck frame according to the second embodiment. [FIG. 11] FIG. 11 is a schematic diagram showing the truck frame according to the second embodiment in the production process. [FIG. 12] FIG. 12 is a side view of a truck frame according to a third embodiment. [FIG. 13] FIG. 13 is a side view of the truck frame according to the third embodiment. [FIG. 14] FIG. 14 is a lateral cross-sectional view of the truck frame according to the third embodiment. [FIG. 15] FIG. 15 is a schematic diagram showing the truck frame according to the third embodiment in the production process. [FIG. 16] FIG. 16 is a lateral cross-sectional view of a truck frame according to a fourth embodiment. [FIG. 17] FIG. 17 is a schematic diagram showing the truck frame according to the fourth embodiment in the production process. [FIG. 18] FIG. 18 is a lateral cross-sectional view of a truck frame according to a fifth embodiment. [FIG. 19] FIG. 19 is a schematic diagram showing the truck frame according to the fifth embodiment in the production process. DESCRIPTION OF EMBODIMENTS

[0011] A truck frame for a railway vehicle according to an embodiment includes a side beam and a cross beam. The side beam includes a top plate part, a bottom plate part opposed to the top plate part, and an inner plate part and an outer plate part that connect the top plate part and the bottom plate part to each other. The side beam extends in a front-and-rear direction of the railway vehicle. The cross beam extends in a left-and-right direction of the railway vehicle. The cross beam penetrates the inner plate part and the outer plate part and is joined to the inner plate part and the outer plate part. The inner plate part is divided into a first inner plate portion and a second inner plate portion. The first inner plate portion is a portion of the inner plate part that is to be joined to the cross beam. The second inner plate portion is the other portion of the inner plate part and is welded to the first inner plate portion. The first inner plate portion is welded to the cross beam at both an inner corner and an outer corner in the left-and-right direction (first configuration).

[0012] The side beam typically has a closed cross-sectional shape. Specifically, the side beam includes the top plate part, bottom plate part opposed to the top plate part, and the inner plate part and the outer plate part that connect the top plate part and the bottom plate part to each other. Typically, a through-hole is formed in each of the inner plate part and the outer plate part of the side beam, and the cross beam is inserted into the through-holes. After that, the inner plate part and the cross beam are joined to each other, and the outer plate part and the cross beam are joined to each other. In this process, the side beam is joined to the cross beam only at corners on the outside of the closed cross section of the side beam, and corners on the inside of the closed cross section are not welded. Specifically, of an inner corner and an outer corner in the left-and-right direction formed by the inner plate part and the cross beam, the inner plate part is welded to the cross beam only at the inner corner and cannot be welded at the outer corner. Similarly, of an inner corner and an outer corner in the left-and-right direction formed by the outer plate part and the cross beam, the outer plate part is welded to the cross beam only at the outer corner and cannot be welded at the inner corner. In the inner plate part and the outer plate part, particularly the joint between the inner plate part and the cross beam is likely to be the most vulnerable to a torsion stress exerted on the cross beam by a motor.

[0013] With the truck frame according to the first configuration, the inner plate part is divided into the first inner plate portion, which is a portion of the inner plate part that is to be joined to the cross beam, and the second inner plate portion, which is the other portion. The first inner plate portion is welded to the cross beam at both the inner corner and the outer corner in the left-and-right direction. That is, the first inner plate portion is welded to the cross beam not only at the corner on the outside of the closed cross section of the side beam but also at the corner on the inside of the closed cross section. In other words, the first inner plate portion is joined to the cross beam by double-sided fillet welding. In this case, the strength of the weld zones between the side beam and the cross beam can be improved, compared with the case where the inner plate part is welded to the cross beam only at the corner on one side.

[0014] The truck frame according to the first configuration may have the following configuration. The truck frame includes two cross beams arranged side by side in the front-and-rear direction. The first inner plate portion is joined to both the cross beams (second configuration). With the truck frame according to the second configuration, one first inner plate portion is joined to both the two cross beams. In this case, the number of parts can be reduced, compared with the case where first inner plate portions to be joined to the two cross beams are separately produced. Therefore, the truck frame can be more easily produced.

[0015] The truck frame according to the first configuration may have the following configuration. The truck frame includes two cross beams arranged side by side in the front-and-rear direction. The inner plate part includes two first inner plate portions each of which is joined to one cross beam (third configuration). With the truck frame according to the third configuration, the inner plate part includes two first inner plate portions, and each of the first inner plate portions is joined to one cross beam. In this case, the shape of the first inner plate portion is simple, compared with the case where one first inner plate portion that is to be joined to both the two cross beams is produced. Therefore, the truck frame can be easily produced.

[0016] With the truck frame according to any one of the configurations described above, the thickness of the first inner plate portion is preferably greater than the thickness of the second inner plate portion (fourth configuration). With the truck frame according to the fourth configuration, the thickness of the first inner plate portion, which is a portion of the inner plate part that is to be joined to the cross beam, is greater than the thickness of the second inner plate portion, which is the other portion of the inner plate part. Therefore, with the truck frame according to the fourth configuration, the strength of the weld zones between the side beam and the cross beam can be improved.

[0017] The truck frame according to any one of the configurations described above may have the following configuration. The outer plate part includes a first outer plate portion and a second outer plate portion. The first outer plate portion is a portion of the outer plate part that is to be joined to the cross beam. The second outer plate portion is the other portion of the outer plate part and is welded to the first outer plate portion. The first outer plate portion is welded to the cross beam at both an inner corner and an outer corner in the left-and-right direction (fifth configuration).

[0018] With the truck frame according to the fifth configuration, the outer plate part is divided into the first outer plate portion, which is a portion of the outer plate part that is to be joined to the cross beam, and the second outer plate portion, which is the other portion of the outer plate portion. The first outer plate portion is welded to the cross beam at both the inner corner and the outer corner in the left-and-right direction. That is, the first outer plate portion is welded to the cross beam not only at the corner on the outside of the closed cross section of the side beam but also at the corner on the inside of the closed cross section. In other words, in the truck frame according to the fifth configuration, not only the first inner plate portion but also the first outer plate portion is welded to the cross beam by double-sided fillet welding. In this case, the strength of the weld zones between the side beam and the cross beam can be further improved, compared with the case where the outer plate part is welded to the cross beam only at the corner on one side.

[0019] With the truck frame according to the fifth configuration, when viewed in the left-and-right direction of the railway vehicle, the contour of the first outer plate portion is preferably located within the contour of the first inner plate portion (sixth configuration). In this case, the side beam and the cross beam can be easily joined to each other.

[0020] A production method according to an embodiment is a production method for the truck frame according to any one of the configurations described above. The production method includes a first joining step and a second joining step. In the first joining step, the first inner plate portion and the cross beam are welded to each other. In the second joining step, the first inner plate portion and the second inner plate portion are welded to each other after the first joining step (seventh configuration).

[0021] In the production method according to the seventh configuration, in the first joining step, the first inner plate portion and the cross beam are welded to each other. In the second joining step, the first inner plate portion and the second inner plate portion are welded to each other after the first joining step. In short, in the side beam, the first inner plate portion is welded to the cross beam before the first inner plate portion is welded to the second inner plate portion, that is, before the closed cross section is formed. Therefore, in the first joining step, the first inner plate portion can be welded to the cross beam at both the inner corner and the outer corner in the left-and-right direction. Thus, in the production method according to the seventh configuration, the strength of the weld zones between the side beam and the cross beam can be improved.

[0022] The production method according to the seventh configuration may have the following configuration. The outer plate part includes a first outer plate portion and a second outer plate portion. The first outer plate portion is a portion of the outer plate part that is to be joined to the cross beam. The second outer plate portion is the other portion of the outer plate part and is welded to the first outer plate portion. In the first joining step, the first outer plate portion and the cross beam are welded to each other. The production method further includes a third joining step. In the third joining step, the first outer plate portion and the second outer plate portion are welded to each other (eighth configuration).

[0023] The production method according to the eighth configuration may have the following configuration. In the second joining step, the first inner plate portion and the second inner plate portion are welded to each other in a state where a back plate is provided on the second inner plate portion. In the third joining step, the first outer plate portion and the second outer plate portion are welded to each other in a state where a back plate is provided on the first outer plate portion (ninth configuration). In the production method according to the ninth configuration, a back plate is used for welding the first inner plate portion and the second inner plate portion to each other. Similarly, a back plate is used for welding the first outer plate portion and the second outer plate portion to each other. In this case, the welding of the members can be efficiently conducted, and the quality of the weld zones are improved.

[0024] In the following, embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding components are denoted by the same reference numerals, and redundant descriptions thereof will be omitted.[First Embodiment][Configuration of Truck]

[0025] FIG. 1 is a schematic diagram showing a general configuration of a railway vehicle 10 that includes a truck frame 30 according to a first embodiment. FIG. 1 shows the railway vehicle 10 viewed in a travel direction. In this specification, the travel direction of the railway vehicle 10 may be referred to as a front-and-rear direction, and the width direction of the railway vehicle 10 may be referred to as a left-and-right direction.

[0026] With reference to FIG. 1, the railway vehicle 10 includes a vehicle body 11 and a truck 20. Trucks 20 are arranged on the front side and the rear side of the vehicle body 11 and support the vehicle body 11. Although the truck 20 is a bolsterless truck in the example shown in FIG. 1, the truck 20 may be a bolster truck.

[0027] The truck 20 includes a truck frame 30, air springs 21 arranged on the left and right sides of the truck frame 30 and a wheel set 22. The air spring 21 is arranged between the vehicle body 11 and the truck frame 30 to support the vehicle body 11 and reduce vibration of the vehicle body 11. Wheel sets 22 are arranged on the front side and the rear side of the truck frame 30. The wheel set 22 has a pair of wheels 221 on the left and right sides thereof and an axle 222 that extends in the left-and-right direction. The left and right wheels 221 are fixed to opposite end parts of the axle 222. Axle boxes 23 are arranged at the left and right sides of the wheel set 22. The axle 222 is rotatably supported by a bearing (not shown) provided in the axle box 23.

[0028] FIG. 2 is a top view of the truck frame 30. With reference to FIGS. 1 and 2, the truck frame 30 includes a pair of side beams 40 on the left and right sides thereof and two cross beams 50. The left and right side beams 40 extend in the front-and-rear direction. The two cross beams 50 are arranged side by side in the front-and-rear direction. The two cross beams 50 each extend in the left-and-right direction and are joined to the left and right side beams 40. The left and right side beams 40 each include a main body 41 that extends in the front-and-rear direction and spring caps 42 and 43 connected to a front end and a rear end of the main body 41. The spring caps 42 and 43 each house an axle spring 24. Each of the left and right side beams 40 is supported by the axle boxes 23 via the axle springs 24. That is, the truck frame 30 is supported by the front and rear wheel sets 22.[Truck Frame]

[0029] In the following, the truck frame 30 according to this embodiment will be described in more detail. FIGS. 3 and 4 are side views of the truck frame 30 according to this embodiment. FIG. 3 shows the side beam 40 viewed from inside of the truck frame 30 (from the center of the railway vehicle 10) in the left-and-right direction, and FIG. 4 shows the side beam 40 viewed from outside of the truck frame 30 in the left-and-right direction. In FIGS. 3 and 4, illustration of the cross beams 50 is omitted.

[0030] With reference to FIGS. 3 and 4, the main body 41 of the side beam 40 has an arc shape projecting downward as a whole when viewed from the side. The main body 41 of the side beam 40 includes a top plate part 411, a bottom plate part 412 opposed to the top plate part 411, and an inner plate part 413 (FIG. 3) and an outer plate part 414 (FIG. 4) that connect the top plate part 411 and the bottom plate part 412 to each other. The inner plate part 413 is opposed to the outer plate part 414. The main body 41 has a closed cross section defined by the top plate part 411, the bottom plate part 412, the inner plate part 413 and the outer plate part 414.

[0031] In each of the inner plate part 413 and the outer plate part 414, two holes 44 are formed through which the cross beam 50 (FIG. 2) is inserted. The cross beam 50 penetrates the inner plate part 413 and the outer plate part 414 and are joined to the inner plate part 413 and the outer plate part 414. The two holes 44 are arranged at a distance in the front-and-rear direction in each of the inner plate part 413 and the outer plate part 414. The shape of the two holes 44 corresponds to the shape of the cross beam 50. For example, the two holes 44 have a circular shape in side view of the side beam 40. In this case, the cross beam 50 may be a circular pipe. However, the shapes of the cross beam 50 and the hole 44 are not limited to these, and the cross beam 50 and the hole 44 may have a rectangular shape when viewed from the side, for example.

[0032] With reference to FIG. 3, the inner plate part 413 is divided into a first inner plate portion 413a and a second inner plate portion 413b. The first inner plate portion 413a is a portion of the inner plate part 413 that is to be joined to the cross beams 50. Both the two holes 44 are formed in the first inner plate portion 413a. That is, the first inner plate portion 413a is joined to both of the two cross beams 50. The second inner plate portion 413b is the other portion of the inner plate part 413, that is, the other portion than the first inner plate portion 413a. In the example in this embodiment, the first inner plate portion 413a is a middle portion of the inner plate part 413 in the front-and-rear direction. The opposite end portions of the inner plate part 413 in the front-and-rear direction are second inner plate portions 413b. The second inner plate portions 413b connect the first inner plate portion 413a to the spring caps 42 and 43. The thickness of the first inner plate portion 413a is preferably greater than the thickness of the second inner plate portions 413b.

[0033] The second inner plate portion 413b and the first inner plate portion 413a are welded to each other at a boundary 45. The first inner plate portion 413a and the second inner plate portion 413b are typically joined to each other by butt welding. The second inner plate portion 413b is further welded to the top plate part 411 and the bottom plate part 412. The second inner plate portion 413b is typically joined to the top plate part 411 and the bottom plate part 412 by fillet welding.

[0034] With reference to FIG. 4, in the example in this embodiment, the outer plate part 414 is divided into a first outer plate portion 414a and a second outer plate portion 414b. The first outer plate portion 414a is a portion of the outer plate part 414 that is to be joined to the cross beams 50. Both the two holes 44 are formed in the first outer plate portion 414a. That is, the first outer plate portion 414a is joined to both of the two cross beams 50. The second outer plate portion 414b is the other portion of the outer plate part 414, that is, the other portion than the first outer plate portion 414a. In the example in this embodiment, the first outer plate portion 414a is a middle portion of the outer plate part 414 in the front-and-rear direction. The opposite end portions of the outer plate part 414 in the front-and-rear direction are second outer plate portions 414b. The second outer plate portions 414b connect the first outer plate portion 414a to the spring caps 42 and 43. The thickness of the first outer plate portion 414a is preferably greater than the thickness of the second outer plate portions 414b.

[0035] The second outer plate portion 414b and the first outer plate portion 414a are welded to each other at a boundary 46. The first outer plate portion 414a and the second outer plate portion 414b are typically joined to each other by butt welding. The second outer plate portion 414b is further welded to the top plate part 411 and the bottom plate part 412. The second outer plate portion 414b is typically joined to the top plate part 411 and the bottom plate part 412 by fillet welding.

[0036] FIG. 5 is a lateral cross-sectional view of the truck frame 30 according to this embodiment. In this specification, the "lateral cross section" refers to a cross section taken perpendicularly to the front-and-rear direction of the railway vehicle 10. FIG. 5 shows a cross section of the truck frame 30 taken at the center of one cross beam 50 in the front-and-rear direction.

[0037] With reference to FIG. 5, the first inner plate portion 413a is joined to the cross beam 50 by double-sided fillet welding. Specifically, the first inner plate portion 413a and the cross beam 50 are welded at both an inner corner 51 and an outer corner 52. The inner corner 51 refers to an inner corner in the left-and-right direction (a corner closer to the center of the railway vehicle 10) of the two corners formed by the first inner plate portion 413a and the cross beam 50. The inner corner 51 is located on the outside of the closed cross section of the main body 41 of the side beam 40. The outer corner 52 refers to an outer corner in the left-and-right direction (a corner farther from the center of the railway vehicle 10) of the two corners formed by the first inner plate portion 413a and the cross beam 50. The outer corner 52 is located on the inside of the closed cross section of the main body 41 of the side beam 40. A bevel is preferably formed in a part of the first inner plate portion 413a that is to be joined to the cross beam 50. A weld zone W1 between the first inner plate portion 413a and the cross beam 50 is formed along the outer periphery of the cross beam 50.

[0038] In the example in this embodiment, the first outer plate portion 414a is joined to the cross beam 50 by double-sided fillet welding. Specifically, the first outer plate portion 414a and the cross beam 50 are welded at both an inner corner 53 and an outer corner 54. The inner corner 53 refers to an inner corner in the left-and-right direction (a corner closer to the center of the railway vehicle 10) of the two corners formed by the first outer plate portion 414a and the cross beam 50. The inner corner 53 is located on the inside of the closed cross section of the main body 41 of the side beam 40. The outer corner 54 refers to an outer corner in the left-and-right direction (a corner farther from the center of the railway vehicle 10) of the two corners formed by the first outer plate portion 414a and the cross beam 50. The outer corner 54 is located on the outside of the closed cross section of the main body 41 of the side beam 40. A bevel is preferably formed in a part of the first outer plate portion 414a that is to be joined to the cross beam 50. A weld zone W2 between the first outer plate portion 414a and the cross beam 50 is formed along the outer periphery of the cross beam 50.

[0039] In the example in this embodiment, the first inner plate portion 413a is welded to the top plate part 411 and the bottom plate part 412, as with the second inner plate portion 413b (FIG. 3). The first inner plate portion 413a is typically joined to the top plate part 411 and the bottom plate part 412 by fillet welding. A bevel is preferably formed in a part of the first inner plate portion 413a that is to be joined to the top plate part 411 and the bottom plate part 412. A weld zone W3 between the first inner plate portion 413a and the top plate part 411 and a weld zone W3 between the first inner plate portion 413a and the bottom plate part 412 are each formed along the front-and-rear direction (the direction of extension of the top plate part 411 and the bottom plate part 412).

[0040] Furthermore, in the example in this embodiment, the first outer plate portion 414a is welded to the top plate part 411 and the bottom plate part 412, as with the second outer plate portion 414b (FIG. 4). The first outer plate portion 414a is typically joined to the top plate part 411 and the bottom plate part 412 by fillet welding. A bevel is preferably formed in a part of the first outer plate portion 414a that is to be joined to the top plate part 411 and the bottom plate part 412. A weld zone W4 between the first outer plate portion 414a and the top plate part 411 and a weld zone W4 between the first outer plate portion 414a and the bottom plate part 412 are each formed along the front-and-rear direction (the direction of extension of the top plate part 411 and the bottom plate part 412). Note that end parts of the cross beam 50 are sealed with a cap 50a.[Production Method for Truck Frame]

[0041] FIG. 6 is a flowchart showing a production method for the truck frame 30 according to this embodiment. As shown in FIG. 6, the production method according to this embodiment includes a first joining step (#5), a second joining step (#10) and a third joining step (#15). In the following, the steps shown in FIG. 6 will be specifically described.

[0042] FIG. 7 is a schematic diagram showing the truck frame 30 according to this embodiment in the production process. At the first joining step (#5), the first inner plate portion 413a and the second inner plate portion 413b are not joined to each other. That is, the first inner plate portion 413a and the second inner plate portion 413b are separately produced. The first inner plate portion 413a and the second inner plate portion 413b may be separately produced or may be produced by producing an integral inner plate part 413 and then cutting the inner plate part 413.

[0043] In the example in this embodiment, at the first joining step (#5), the first outer plate portion 414a is also not joined to the second outer plate portion 414b. That is, the first outer plate portion 414a and the second outer plate portion 414b are separately produced, as with the first inner plate portion 413a and the second inner plate portion 413b.

[0044] Before the first joining step (#5), the second inner plate portion 413b is welded to the top plate part 411 and the bottom plate part 412. The second outer plate portion 414b is welded to the top plate part 411 and the bottom plate part 412. In this way, the side beam 40 is assembled except the first inner plate portion 413a and the first outer plate portion 414a.

[0045] In the first joining step (#5), the cross beams 50 are inserted into the holes 44 formed in the first inner plate portion 413a. At the same time, the cross beams 50 are inserted into the holes 44 formed in the first outer plate portion 414a. Then, the first inner plate portion 413a is welded to the cross beams 50. That is, the first inner plate portion 413a, which is a portion of the inner plate part 413 of the side beam 40, is welded to the cross beams 50 before the first inner plate portion 413a is welded to the other parts of the side beam 40 (the top plate part 411, the bottom plate part 412 and the second inner plate portion 413b). Similarly, in the first joining step (#5), the first outer plate portion 414a and the cross beams 50 are welded to each other. That is, the first outer plate portion 414a, which is a portion of the outer plate part 414 of the side beam 40, is welded to the cross beams 50 before the first outer plate portion 414a is welded to the other parts of the side beam 40 (the top plate part 411, the bottom plate part 412 and the second outer plate portion 414b).

[0046] When the first inner plate portion 413a and the first outer plate portion 414a are welded to the cross beams 50, the first inner plate portion 413a, the first outer plate portion 414a and the cross beams 50 do not form a closed cross section. Therefore, in the first joining step (#5), the first inner plate portion 413a and the first outer plate portion 414a can be joined to the cross beams 50 by double-sided filet welding.

[0047] In the second joining step (#10), following the first joining step (#5), the first inner plate portion 413a is welded to the second inner plate portions 413b. In the example in this embodiment, in the second joining step (#10), the first inner plate portion 413a is welded to the top plate part 411 and the bottom plate part 412.

[0048] In the third joining step (#15), the first outer plate portion 414a and the second outer plate portions 414b are welded to each other. The third joining step (#15) is typically performed at the same time as the second joining step (#10). In the example in this embodiment, in the third joining step (#15), the first outer plate portion 414a is welded to the top plate part 411 and the bottom plate part 412.

[0049] In the second joining step (#10) and the third joining step (#15), the truck frame 30 shown in FIG. 5 is produced. At this point, the side beam 40 and the cross beams 50 form a closed cross section. Therefore, the first inner plate portion 413a is joined to the top plate part 411 only on the outside of the closed cross section by fillet welding. Furthermore, the first inner plate portion 413a is joined to the bottom plate part 412 only on the outside of the closed cross section by fillet welding. Similarly, the first outer plate portion 414a is joined to the top plate part 411 only on the outside of the closed cross section by fillet welding. Furthermore, the first outer plate portion 414a is joined to the bottom plate part 412 only on the outside of the closed cross section by fillet welding.[Effects]

[0050] With the truck frame 30 according to this embodiment, the inner plate part 413 is divided into the first inner plate portion 413a, which is a portion to be joined to the cross beams 50, and the second inner plate portions 413b, which are the other portions. The first inner plate portion 413a is welded to the cross beam 50 at both the inner corner 51 and the outer corner 52 in the left-and-right direction. That is, the first inner plate portion 413a is welded to the cross beam 50 not only at the corner on the outside of the closed cross section of the side beam 40 but also at the corner on the inside of the closed cross section. In other words, the first inner plate portion 413a is joined to the cross beam 50 by double-sided fillet welding. With the truck frame 30 according to this embodiment, not only the first inner plate portion 413a but also the first outer plate portion 414a is joined to the cross beam 50 by double-sided fillet welding. In this case, the strength of the weld zones between the side beam 40 and the cross beam 50 can be improved, compared with the case where the inner plate part 413 and the outer plate part 414 are each welded to the cross beam 50 only at the corner on one side.

[0051] With the truck frame 30 according to this embodiment, one first inner plate portion 413a is joined to both the two cross beams 50. In this case, the number of parts can be reduced, compared with the case where first inner plate portions 413a to be joined to the two cross beams 50 are separately produced. Therefore, the truck frame 30 can be more easily produced.

[0052] With the truck frame 30 according to this embodiment, the thickness of the first inner plate portion 413a, which is a portion of the inner plate part 413 that is to be joined to the cross beams 50, is greater than the thickness of the second inner plate portions 413b, which are the other portions of the inner plate part 413. In this case, the strength of the weld zones between the side beam 40 and the cross beam 50 can be improved.

[0053] In the production method for the truck frame 30 according to this embodiment, in the first joining step (#5), the first inner plate portion 413a and the cross beams 50 are welded to each other. In the second joining step (#10), following the first joining step (#5), the first inner plate portion 413a and the second inner plate portions 413b are welded to each other. In short, in the side beam 40, the first inner plate portion 413a is welded to the cross beams 50 before the first inner plate portion 413a is welded to the second inner plate portions 413b, that is, before the closed cross section is formed. Therefore, in the first joining step (#5), the first inner plate portion 413a can be welded to the cross beam 50 at both the inner corner 51 and the outer corner 52 in the left-and-right direction. Thus, in the production method according to this embodiment, the truck frame 30 that has the first inner plate portion 413a joined to the cross beams 50 by double-sided fillet welding can be produced.[Second Embodiment]

[0054] With reference to FIGS. 8 to 10, a truck frame 30 according to a second embodiment will be described. FIGS. 8 and 9 are side views of the truck frame 30 according to this embodiment. FIG. 8 shows a side beam 40 viewed from inside of the truck frame 30 (from the center of the railway vehicle 10) in the left-and-right direction, and FIG. 9 shows the side beam 40 viewed from outside of the truck frame 30 in the left-and-right direction. In FIGS. 8 and 9, illustration of the cross beams 50 is omitted. FIG. 10 is a lateral cross-sectional view of the truck frame 30 according to this embodiment. FIG. 10 shows a cross section of the truck frame 30 taken at the center of one cross beam 50 in the front-and-rear direction.

[0055] With reference to FIGS. 8 to 10, the truck frame 30 according to this embodiment differs from the truck frame 30 according to the first embodiment in shape of a first inner plate portion 413a and shape of a first outer plate portion 414a. In other words, the truck frame 30 according to this embodiment differs from the truck frame 30 according to the first embodiment in manner of division of an inner plate part 413 into a first inner plate portion 413a and a second inner plate portion 413b. Furthermore, the truck frame 30 according to this embodiment differs from the truck frame 30 according to the first embodiment in manner of division of an outer plate part 414 into a first outer plate portion 414a and a second outer plate portion 414b.

[0056] In the example in this embodiment, as shown in FIGS. 8 and 9, the first inner plate portion 413a and the first outer plate portion 414a have a substantially elliptical shape in side view. The first inner plate portion 413a is not joined to a top plate part 411 and a bottom plate part 412 and is joined to only the second inner plate portion 413b. In the second inner plate portion 413b, a hole corresponding to the contour of the first inner plate portion 413a is formed. A bevel is preferably formed in parts of the first inner plate portion 413a and the second inner plate portion 413b that are to be joined to each other. A weld zone W5 is formed along a boundary 45 between the first inner plate portion 413a and the second inner plate portion 413b.

[0057] Similarly, the first outer plate portion 414a is not joined to the top plate part 411 and the bottom plate part 412 and is joined to only the second outer plate portion 414b. In the second outer plate portion 414b, a hole corresponding to the contour of the first outer plate portion 414a is formed. A bevel is preferably formed in parts of the first outer plate portion 414a and the second outer plate portion 414b that are to be joined to each other. A weld zone W6 is formed along a boundary 46 between the first outer plate portion 414a and the second outer plate portion 414b.

[0058] When viewed from the side, the contour of the first inner plate portion 413a is substantially the same as the contour of the first outer plate portion 414a. That is, when viewed in the left-and-right direction, the size of the first outer plate portion 414a is substantially the same as the size of the first inner plate portion 413a. However, the contour of the first inner plate portion 413a may be larger than the contour of the first outer plate portion 414a.

[0059] In the example shown in FIG. 10, the thickness of the first inner plate portion 413a is the same as the thickness of the second inner plate portion 413b, and the thickness of the first outer plate portion 414a is the same as the thickness of the second outer plate portion 414b. However, as in the first embodiment, the thickness of the first inner plate portion 413a may be greater than the thickness of the second inner plate portion 413b, and the thickness of the first outer plate portion 414a may be greater than the thickness of the second outer plate portion 414b.

[0060] FIG. 11 is a schematic diagram showing the truck frame 30 according to this embodiment in the production process. With reference to FIG. 11, in this embodiment, when the first inner plate portion 413a and the first outer plate portion 414a are welded to the cross beams 50, the first inner plate portion 413a, the first outer plate portion 414a and the cross beams 50 do not form a closed cross section, as in the first embodiment. Therefore, in a first joining step (#5), the first inner plate portion 413a and the first outer plate portion 414a can be joined to the cross beams 50 by double-sided filet welding. Therefore, with the truck frame 30 according to this embodiment, the strength of the weld zones between the side beam 40 and the cross beam 50 can be improved, as with the truck frame 30 according to the first embodiment.[Third Embodiment]

[0061] With reference to FIGS. 12 to 14, a truck frame 30 according to a third embodiment will be described. FIGS. 12 and 13 are side views of the truck frame 30 according to this embodiment. FIG. 12 shows a side beam 40 viewed from inside of the truck frame 30 (from the center of the railway vehicle 10) in the left-and-right direction, and FIG. 13 shows the side beam 40 viewed from outside of the truck frame 30 in the left-and-right direction. In FIGS. 12 and 13, illustration of the cross beams 50 is omitted. FIG. 14 is a lateral cross-sectional view of the truck frame 30 according to this embodiment. FIG. 14 shows a cross section of the truck frame 30 taken at the center of one cross beam 50 in the front-and-rear direction.

[0062] With reference to FIGS. 12 to 14, with the truck frame 30 according to this embodiment, an inner plate part 413 is divided into two first inner plate portions 413a and one second inner plate portion 413b. Each of the first inner plate portions 413a has a hole 44 through which a cross beam 50 is inserted. That is, each of the first inner plate portions 413a is joined to one cross beam 50.

[0063] Furthermore, with the truck frame 30 according to this embodiment, an outer plate part 414 is divided into two first outer plate portions 414a and one second outer plate portion 414b. Each of the first outer plate portions 414a has a hole 44 through which the cross beam 50 is inserted. That is, each of the first outer plate portions 414a is joined to one cross beam 50.

[0064] In the example in this embodiment, the first inner plate portion 413a and the first outer plate portion 414a have a substantially circular shape in side view. However, the shape of the first inner plate portion 413a slightly differs from the shape of the first outer plate portion 414a. When viewed from the side, the contour (diameter) of the first inner plate portion 413a is larger than the contour (diameter) of the first outer plate portion 414a. Specifically, when viewed in the left-and-right direction, the contour of the first outer plate portion 414a is located within the contour of the first inner plate portion 413a. In other words, when viewed in the left-and-right direction, the first inner plate portion 413a overlaps with the whole of the first outer plate portion 414a.

[0065] FIG. 15 is a schematic diagram showing the truck frame 30 according to this embodiment in the production process. When joining a side beam 40 and the cross beam 50 to each other, the cross beam 50 is inserted into holes formed in the side beam 40 from the inside in the left-and-right direction (from the side of the center of the railway vehicle 10). With reference to FIG. 15, in the example in this embodiment, when viewed in the left-and-right direction, the first outer plate portion 414a is smaller than the first inner plate portion 413a as described above. Therefore, the cross beam 50 (including the first outer plate portion 414a joined to the cross beam 50 in a first joining step (#5)) is easily inserted into a hole formed in the second inner plate portion 413b. Therefore, the joining of the first inner plate portions 413a and the second inner plate portion 413b in a second joining step (#10) and the joining of the first outer plate portions 414a and the second outer plate portion 414b in a third joining step (#15) can be easily performed.

[0066] In the example in this embodiment, furthermore, in the first joining step (#5), a back plate 47 is provided on the second inner plate portion 413b joined to a top plate part 411 and a bottom plate part 412. The back plate 47 is disposed on the outer side of the second inner plate portion 413b in the left-and-right direction, that is, on the inside of the closed cross section finally formed by the side beam 40 and the cross beams 50. The back plate 47 is provided along a boundary 45 between the first inner plate portion 413a and the second inner plate portion 413b and has a ring shape when viewed in the left-and-right direction, for example. In the second joining step (#10), the first inner plate portion 413a and the second inner plate portion 413b with the back plate 47 provided thereon are welded to each other. In this case, in the second joining step (#10), the first inner plate portion 413a and the second inner plate portion 413b are joined to each other in such a manner that the outer faces thereof in the left-and-right direction are flush with each other.

[0067] Furthermore, in the first joining step (#5), a back plate 48 is provided on the first outer plate portion 414a joined to the cross beam 50. The back plate 48 is disposed on the inner side of the first outer plate portion 414a in the left-and-right direction, that is, on the inside of the closed cross section finally formed by the side beam 40 and the cross beams 50. The back plate 48 is provided along a boundary 46 between the first outer plate portion 414a and the second outer plate portion 414b and has a ring shape when viewed in the left-and-right direction, for example. In the third joining step (#15), the first outer plate portion 414a with the back plate 48 provided thereon and the second outer plate portion 414b are joined to each other. In this case, in the third joining step (#15), the first outer plate portion 414a and the second outer plate portion 414b are joined to each other in such a manner that the inner faces thereof in the left-and-right direction are flush with each other.

[0068] In this embodiment, the back plate 47 is used for welding the first inner plate portion 413a and the second inner plate portion 413b to each other. Similarly, the back plate 48 is used for welding the first outer plate portion 414a and the second outer plate portion 414b to each other. In this case, the welding of the members can be efficiently conducted, and the quality of the weld zones are improved.

[0069] With the truck frame 30 according to this embodiment, as described above, the inner plate part 413 includes two first inner plate portions 413a, and each of the first inner plate portions 413a is joined to one cross beam 50. In this case, the shape of the first inner plate portion 413a is simple, compared with the case where one first inner plate portion 413a that is to be joined to both the two cross beams 50 is produced. Therefore, the truck frame 30 can be easily produced.[Fourth Embodiment]

[0070] With reference to FIGS. 16 and 17, a truck frame 30 according to a fourth embodiment will be described. FIG. 16 is a lateral cross-sectional view of the truck frame 30 according to this embodiment. FIG. 16 shows a cross section of the truck frame 30 taken at the center of one cross beam 50 in the front-and-rear direction. FIG. 17 is a schematic diagram showing the truck frame 30 according to this embodiment in the production process.

[0071] In the example in this embodiment, an inner plate part 413 has the same shape as the inner plate part 413 according to the third embodiment shown in FIGS. 12 and 14. However, the shape of an outer plate part 414 differs from the shape of any of the outer plate parts 414 according to the embodiments described above. Specifically, in this embodiment, the outer plate part 414 is not divided into a first outer plate portion 414a and a second outer plate portion 414b. That is, in a first joining step (#5), only first inner plate portions 413a of the inner plate part 413 are joined to cross beams 50, and the outer plate part 414 is not joined to the cross beams 50. In this case, in the first joining step (#5), a back plate 48 is provided on an outer peripheral face of the cross beam 50.

[0072] With the truck frame 30 according to this embodiment, the outer plate part 414, which is a part of a side beam 40, is welded to the cross beams 50 after a closed cross section is formed by the side beam 40 and the cross beams 50. In this case, the outer plate part 414 can be welded to the cross beam 50 only at a corner on the outside of the closed cross section. Therefore, the outer plate part 414 is welded to the cross beam 50 at an outer corner 54 in the left-and-right direction but is not welded at an inner corner 53. With the truck frame 30 according to this embodiment, however, the inner plate part 413 (first inner plate portion 413a) is welded to the cross beam 50 not only at a corner on the outside of the closed cross section of the side beam 40 but also at a corner on the inside of the closed cross section. In general, the joints between the inner plate part 413 and the cross beams 50 are likely to be more vulnerable to a torsion stress exerted on the cross beams 50 by a motor than the joints between the outer plate part 414 and the cross beams 50. Therefore, with the truck frame 30 according to this embodiment, the strength of the weld zones between the side beam 40 and the cross beams 50 can be improved compared with the case where the inner plate part 413 is welded to the cross beams 50 only at the corner on one side.[Fifth Embodiment]

[0073] With reference to FIGS. 18 and 19, a truck frame 30 according to a fifth embodiment will be described. FIG. 18 is a lateral cross-sectional view of the truck frame 30. FIG. 18 shows a cross section of the truck frame 30 taken at the center of one cross beam 50 in the front-and-rear direction. FIG. 19 is a schematic diagram showing the truck frame 30 according to this embodiment in the production process.

[0074] With the truck frame 30 according to this embodiment, a first inner plate portion 413a of an inner plate part 413 is welded not only to a second inner plate portion 413b but also to a top plate part 411 and a bottom plate part 412, as with the inner plate part 413 according to the first embodiment (FIGS. 3 and 5). Furthermore, an outer plate part 414 is not divided into a first outer plate portion 414a and a second outer plate portion 414b, as with the outer plate part 414 according to the fourth embodiment (FIG. 16). In the example in this embodiment, in a first joining step (#5), a back plate 47 is provided on surfaces of the top plate part 411 and the bottom plate part 412 (faces on the inside of the closed cross section formed by a side beam 40 and cross beams 50).

[0075] With the truck frame 30 according to this embodiment, both the distance from the cross beam 50 to the top plate part 411 and the distance from the cross beam 50 to the bottom plate part 412 are smaller than those in the truck frame 30 according to each embodiment described above. Therefore, according to this embodiment, the truck frame 30 can be reduced in size.

[0076] Embodiments of the present disclosure have been described above. However, the embodiments described above are just intended to illustrate the present disclosure. The present disclosure is not limited to the embodiments described above, and modifications can be appropriately made to the embodiments described above without departing from the spirit of the present disclosure.REFERENCE SIGNS LIST

[0077] 10railway vehicle 30truck frame 40side beam 411top plate part 412bottom plate part 413inner plate part 413afirst inner plate portion 413bsecond inner plate portion 414outer plate part 414afirst outer plate portion 414bsecond outer plate portion 47back plate 48back plate 50cross beam 51inner corner 52outer corner 53inner corner 54outer corner

Claims

1. A truck frame for a railway vehicle, comprising: a side beam that extends in a front-and-rear direction of the railway vehicle, the side beam comprising a top plate part, a bottom plate part opposed to the top plate part, and an inner plate part and an outer plate part that connect the top plate part and the bottom plate part to each other; and a cross beam that extends in a left-and-right direction of the railway vehicle, the cross beam penetrating the inner plate part and the outer plate part and being joined to the inner plate part and the outer plate part, wherein the inner plate part is divided into a first inner plate portion, which is a portion of the inner plate part that is to be joined to the cross beam, and a second inner plate portion, which is the other portion of the inner plate part and is welded to the first inner plate portion, and the first inner plate portion is welded to the cross beam at both an inner corner and an outer corner in the left-and-right direction.

2. The truck frame according to claim 1, wherein the truck frame comprises two of the cross beams arranged side by side in the front-and-rear direction, and the first inner plate portion is joined to both the cross beams.

3. The truck frame according to claim 1, wherein the truck frame comprises two of the cross beams arranged side by side in the front-and-rear direction, and the inner plate part includes two of the first inner plate portions each of which is joined to one of the cross beams.

4. The truck frame according to claim 1, wherein a thickness of the first inner plate portion is greater than a thickness of the second inner plate portion.

5. The truck frame according to claim 1, wherein the outer plate part includes a first outer plate portion, which is a portion of the outer plate part that is to be joined to the cross beam, and a second outer plate portion, which is the other portion of the outer plate part and is welded to the first outer plate portion, and the first outer plate portion is welded to the cross beam at both an inner corner and an outer corner in the left-and-right direction.

6. The truck frame according to claim 5, wherein when viewed in the left-and-right direction, a contour of the first outer plate portion is located within a contour of the first inner plate portion.

7. A production method for the truck frame according to claim 1, comprising: a first joining step of welding the first inner plate portion and the cross beam to each other; and a second joining step of welding the first inner plate portion and the second inner plate portion to each other after the first joining step.

8. The production method for the truck frame according to claim 7, wherein the outer plate part includes a first outer plate portion, which is a portion of the outer plate part that is to be joined to the cross beam, and a second outer plate portion, which is the other portion of the outer plate part and is welded to the first outer plate portion, in the first joining step, the first outer plate portion and the cross beam are welded to each other, and the production method further comprises a third joining step of welding the first outer plate portion and the second outer plate portion to each other.

9. The production method for the truck frame according to claim 8, wherein in the second joining step, the first inner plate portion and the second inner plate portion are welded to each other in a state where a back plate is provided on the second inner plate portion, and in the third joining step, the first outer plate portion and the second outer plate portion are welded to each other in a state where a back plate is provided on the first outer plate portion.

Images